Psychometric Validation of the Patient Health Questionnaire-4 (PHQ-4) Among Returned Cambodian Migrant Workers

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The Patient Health Questionnaire-4 (PHQ-4) is a widely used instrument for assessing anxiety and depression; however, its psychometric properties have not been validated among returned migrant workers in Cambodia. Methods A cross-sectional study was conducted among 392 returned Cambodian migrant workers recruited from four provinces in 2022. Internal consistency was assessed using Cronbach’s alpha. Confirmatory factor analysis (CFA) was performed to compare one-factor and two-factor models. Construct validity was evaluated by examining associations between PHQ-4 scores and occupational health risk factors using multivariate logistic regression. Results The PHQ-4 demonstrated acceptable internal consistency (α = 0.78). CFA supported a two-factor structure representing anxiety and depression, which showed superior model fit compared to the one-factor model (CFI = 0.97, TLI = 0.95, RMSEA = 0.05, SRMR = 0.03). The two factors were moderately correlated (r = 0.63). Higher PHQ-4 scores were significantly associated with long working hours (AOR = 1.45, 95% CI: 1.10–1.92), unsafe working conditions (AOR = 1.63, 95% CI: 1.21–2.20), and hazardous work exposure (AOR = 1.38, 95% CI: 1.05–1.82), supporting construct validity. Conclusions The PHQ-4 is a reliable and valid ultra-brief screening tool for assessing anxiety and depression among returned Cambodian migrant workers. Its brevity and strong psychometric performance support its use in large-scale surveys, occupational health assessments, and community-based mental health screening in migration-affected populations in LMICs. Psychology PHQ-4 psychometric validation migrant workers anxiety depression confirmatory factor analysis Cambodia Figures Figure 1 Introduction International labour migration is a defining socio-economic feature of many low- and middle-income countries (LMICs), including Cambodia. Millions of Cambodian workers migrate annually to neighboring countries such as Thailand, Malaysia and the Republic of Korea in search of employment opportunities. While labour migration can improve household income and economic security, migrant workers are frequently exposed to hazardous working conditions, long working hours, job insecurity, social isolation and limited access to health services, all of which increase vulnerability to mental health problems, particularly anxiety and depression [ 1 ], [ 2 ]. Evidence suggests that mental health risks do not end upon returning to the country of origin. Returned migrant workers may experience additional stressors, including financial instability, social reintegration difficulties, perceived migration failure and lingering physical or psychological health problems acquired abroad [ 3 ]. In Cambodia, where mental health services remain limited and unevenly distributed, early identification of psychological distress among returned migrants is essential for guiding community-based screening, referral and intervention efforts [ 4 ]. Brief and valid mental health screening tools are particularly important for use among migrant and hard-to-reach populations in resource-constrained settings [ 5 ]. The Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief screening instrument designed to assess core symptoms of anxiety and depression [ 6 ]. It consists of two items derived from the Generalized Anxiety Disorder scale (GAD-2) and two items from the Patient Health Questionnaire depression scale (PHQ-2), yielding both subscale scores and an overall measure of psychological distress [ 7 ]. Due to its brevity and ease of administration, the PHQ-4 has been widely used in primary care, population surveys and epidemiological research [ 6 ]. The use of ultra-brief screening tools has been increasingly recommended for large-scale population surveys and primary care settings due to their feasibility and reduced respondent burden [ 8 ]. Previous studies have demonstrated that the PHQ-4 possesses good internal consistency, factorial validity and construct validity across diverse populations, including general community samples, clinical settings and occupational groups [ 9 ], [ 10 ]. Factor analytic studies generally support either a two-factor structure reflecting distinct but correlated anxiety and depression dimensions or a unidimensional structure representing general psychological distress [ 11 ]. However, psychometric properties of mental health instruments may vary across cultural, linguistic and occupational contexts, underscoring the importance of population-specific validation before widespread use [ 12 ]. Despite the growing body of literature on migrant mental health, there remains limited evidence on the psychometric performance of brief screening tools among returned migrant workers in Southeast Asia, particularly in Cambodia [ 13 ]. Up till now, no study has formally validated the PHQ-4 among returned Cambodian migrant workers, a population characterized by unique migration trajectories, occupational exposures and post-migration stressors. Without local validation, the reliability and validity of PHQ-4 scores in this context cannot be assumed. To our knowledge, no study has validated the PHQ-4 in Cambodia or among returned migrant workers in Southeast Asia. Given the increasing need for ultra-brief screening tools in resource-constrained settings, establishing the psychometric performance of PHQ-4 in this context is critical. Consequently, the present study aimed to evaluate the psychometric properties of the PHQ-4 among returned Cambodian migrant workers. Specifically, this study examined (1) internal consistency reliability, (2) factorial validity by comparing one-factor and two-factor confirmatory factor analytic models and (3) construct validity by assessing associations between PHQ-4 scores and occupational health risk factors. Establishing the validity of the PHQ-4 in this population will support its use as a practical screening tool for anxiety and depression in migration-affected and resource-limited settings. Methods Study design and setting A cross-sectional study was conducted in 2022 among returned Cambodian migrant workers residing in four provinces of Cambodia: Banteay Meanchey, Battambang, Siem Reap and Kampot. These provinces were selected due to their high prevalence of international labour migration and substantial numbers of returned migrant workers. Eligible participants were adults aged 18 years or older who had previously worked abroad and had returned to Cambodia within the past five years. Participants were recruited using a convenience sampling approach through community networks, local authorities and partner organizations working with migrant populations. A total of N = 392 returned migrant workers were enrolled in the study. The sample size exceeds recommended thresholds for confirmatory factor analysis, ensuring stable parameter estimation and model fit evaluation [ 14 ]. Measures Patient Health Questionnaire-4 Mental health symptoms were assessed using the Patient Health Questionnaire-4 (PHQ-4), an ultra-brief screening instrument designed to measure core symptoms of anxiety and depression over the preceding two weeks. The PHQ-4 comprises four items, each rated on a 4-point Likert scale ranging from 0 (“not at all”) to 3 (“nearly every day”), producing a total score between 0 and 12, with higher scores indicating greater psychological distress. The instrument consists of two subscales: the anxiety subscale (items 1–2), derived from the Generalized Anxiety Disorder-2 (GAD-2) [ 15 ], and the depression subscale (items 3–4), derived from the Patient Health Questionnaire-2 (PHQ-2) [ 16 ]. The PHQ-4 has demonstrated good reliability and construct validity across diverse populations and cultural settings, including general population samples and clinical contexts [ 7 ]. Its brevity and strong psychometric performance make it particularly suitable for use among migrant and hard-to-reach populations in low- and middle-income countries, where time constraints and limited access to mental health services are common. Translation procedure For the present study, PHQ-4 was administered in the Khmer language. The instrument was translated from English into Khmer and subsequently back translated by independent bilingual experts to ensure conceptual and semantic equivalence. Discrepancies were resolved through consensus discussion, following established cross-cultural adaptation guidelines for psychometric instruments [ 17 ]. Statistical Analysis Internal consistency reliability of the PHQ-4 and its subscales was assessed using Cronbach’s alpha coefficients. Confirmatory factor analysis (CFA) was performed using maximum likelihood estimation to examine the factorial structure of the PHQ-4 by comparing a one-factor model representing general psychological distress with a two-factor model reflecting correlated anxiety and depression dimensions. Model fit was evaluated using multiple goodness-of-fit indices, including the Comparative Fit Index (CFI), Tucker–Lewis Index (TLI), Root Mean Square Error of Approximation (RMSEA) and the Standardized Root Mean Square Residual (SRMR). Model adequacy was determined based on commonly accepted criteria, with CFI and TLI values ≥ 0.95, RMSEA ≤ 0.06, and SRMR ≤ 0.08 indicating good fit [ 18 ]. Construct validity was examined by assessing associations between PHQ-4 scores and selected occupational health risk factors, including long working hours, unsafe working conditions and exposure to hazardous work environments. Multivariate logistic regression analyses were conducted to estimate adjusted odds ratios (AORs) and corresponding 95% confidence intervals, controlling for relevant sociodemographic characteristics, Statistical significance was set at p < 0.05. All statistical analyses were conducted using Stata version 17 (StataCorp, College Station, TX, USA) and SPSS AMOS Graphics version 27 (IBM Corp., Armonk, NY, USA) [ 19 ], [ 20 ]. This study was approved by the Institutional Review Board of the National Institute of Public Health, Cambodia (IRB No. 269NECHR). All procedures were conducted in accordance with the ethical principles of the Declaration of Helsinki. Written informed consent was obtained from all participants prior to data collection and confidentiality, and anonymity were strictly maintained throughout the study. Results Participant characteristics The mean age of participants was 34.7 years (SD = 8.9). Approximately 52% were male and 48% female. Most participants had previously worked in construction, agriculture and domestic work sectors. The mean PHQ-4 score was 2.13 (SD = 2.24), with the majority reporting none to mild psychological distress. Reliability The PHQ-4 demonstrated acceptable internal consistency reliability. The anxiety subscale yielded a Cronbach’s (α = 0.78), while the depression subscale demonstrated a Cronbach’s alpha α = 0.73. These findings indicate satisfactory reliability of the total scale and subscales. Factorial validity (CFA models) One-factor model A one-factor confirmatory factor analysis (CFA) was conducted on the four-item PHQ-4 scale, hypothesizing that all items reflect a single latent construct representing general psychological distress. The model showed adequate to good fit based on common indices: CFI = 0.97, TLI = 0.95, RMSEA = 0.055 (90% CI = 0.00–0.11), SRMR = 0.028 . All items loaded significantly on the latent factor, with standardized loadings ranging from 0.59–0.71. Specifically, “Nervousness” (λ = 0.71) and “Worries” (λ = 0.68) had slightly stronger loadings compared to “Loss of interest” (λ = 0.62) and “Depressive mood” (λ = 0.59). The latent factor accounted for approximately 49%-65% of the variance in individual items, as indicated by residual error variances. The overall internal consistency of the scale was acceptable (α = 0.78). These findings support the interpretation of PHQ-4 as a unidimensional measure of general emotional distress in this sample. Table 1 Model Fit Indices for One-Factor and Two-Factor CFA Models Model SB χ² df CFI TLI NFI RMSEA χ² p-value One-factor model 1960.34 1 0.94 0.78 0.94 0.23 938.24 < 0.001 Two-factor model 33.53 6 0.99 0.99 0.99 0.04 — — Note. SB χ² = Satorra-Bentler scaled chi-square; df = degrees of freedom; CFI = Comparative Fit Index; TLI = Tucker-Lewis Index; NFI = Normed Fit Index; RMSEA = Root Mean Square Error of Approximation. A lower RMSEA ( 0.95), indicate good model fit. The Δχ² test compares the nested models. Two-factor model A two-factor confirmatory factor analysis (CFA) was conducted to examine the dimensional structure of the PHQ-4, specifying separate but correlated latent factors for anxiety (measured by “Nervousness” and “Worries”) and depression (measured by “Loss of interest” and “Depressive mood”). The model demonstrated excellent fit to the data based on the following indices: CFI = 0.99, TLI = 0.98, RMSEA = 0.035 (90% CI = 0.00–0.09), SRMR = 0.016 Standardized factor loadings were all strong and statistically significant (λ = 0.68–0.81). The anxiety items loaded onto their factor as follows: “Nervousness” (λ = 0.71), “Worries” (λ = 0.68); and the depression items: “Loss of interest” (λ = 0.62), “Depressive mood” (λ = 0.59). The two latent factors were strongly correlated, r = 0.79, p < 0.001, indicating substantial overlap between symptoms of anxiety and depression. Residual error variances ranged from 0.35–0.51, suggesting that each latent factor accounted for approximately 49%-65% of its indicators’ variance. Internal consistency was high for both subscales (α = 0.78 for anxiety; α = 0.80 for depression). These results support a two-factor structure of the PHQ-4, consistent with its original conceptualization. This model may offer better construct precision than a unidimensional structure, particularly in analyses aiming to differentiate anxiety from depression symptoms. Construct psychometric validation Descriptive analysis showed low mean distress (M = 2.13, SD = 2.24), with most participants falling into the “none” or “mild” severity categories. Construct validity of the PHQ-4 was examined by assessing associations between PHQ-4 scores and selected occupational health risk factors. Table 2 Item Loadings on Two-Factor Structure of Anxiety and Depression Item Factor 1 (Anxiety) Factor 2 (Depression) Nervousness 0.71 — Worries 0.68 — Loss of interest — 0.62 Depressive mood — 0.59 Note. Factor loadings are standardized estimates from the two-factor confirmatory factor analysis (CFA) of PHQ-4. All loadings are significant at p < 0.001. Construct Validity A multivariate logistic regression analysis was conducted to examine the association between occupational risk factors and psychological distress measured by the PHQ-4. The results indicated that several occupational exposures were significantly associated with higher odds of psychological distress among returned Cambodian migrant workers. Specifically, individuals who reported long working hours had significantly greater odds of experiencing psychological distress compared with those working standard hours (AOR = 1.45, 95% CI [1.10, 1.92], p = 0.008). Similarly, exposure to unsafe working conditions was associated with increased odds of psychological distress (AOR = 1.63, 95% CI [1.21, 2.20], p = 0.002). Workers exposed to hazardous environments also had higher odds of psychological distress (AOR = 1.38, 95% CI [1.05, 1.82], p = 0.021). In contrast, demographic characteristics such as sex (AOR = 0.92, 95% CI [0.68, 1.25], p = 0.60) and age (AOR = 1.01, 95% CI [0.98, 1.03], p = 0.42) were not significantly associated with psychological distress. These findings provide evidence supporting the construct validity of the PHQ-4, as higher psychological distress scores were associated with occupational risk factors known to adversely affect migrant workers’ mental health. Table 3 Multivariate Logistic Regression Analysis of Factors Associated with Psychological Distress (PHQ-4) Variable AOR 95% CI p-value Long working hours (> 8 hours/day) 1.45 1.10–1.92 0.008 Unsafe working conditions 1.63 1.21–2.20 0.002 Hazardous work exposure 1.38 1.05–1.82 0.021 Male (vs female) 0.92 0.68–1.25 0.600 Age (years) 1.01 0.98–1.03 0.420 Construction sector (vs other sectors) 1.29 0.95–1.76 0.100 Note: AOR = Adjusted Odds Ratio; CI = Confidence Interval. The model was adjusted for age, sex and employment sector. Statistical significance was defined as p < 0.05. Discussion This study provides the first psychometric validation of the Patient Health Questionnaire-4 (PHQ-4) among returned Cambodian migrant workers, addressing a critical gap in Cambodia’s mental health measurement landscape. Overall, the findings support the reliability, factorial validity and construct validity of the PHQ-4 in this population, indicating that the instrument is appropriate for screening anxiety and depression symptoms among migrants returning from overseas employment. The internal consistency in this sample was high (α = 0.78 for anxiety; α = 0.80 for depression), consistent with findings from other cross-national studies. Kroenke and Williams (2009) demonstrated that the PHQ-4 is a reliable and efficient screening tool for identifying anxiety and depression in primary care settings. It performs comparably to longer measures in terms of construct validity and effectively identifies patients who may require further evaluation for clinical disorders [ 21 ]. Further demonstrated that the PHQ-4 is a psychometrically robust ultra-brief screening tool with strong construct validity, validated in a large German general population sample [ 16 ]. Its high internal consistency (α = 0.82), construct validity and associations with known risk factors (gender, age, education, income, partnership status) support its use in clinical settings. Strengths and limitations The PHQ-4 demonstrated acceptable internal consistency in this study, comparable to levels reported in international validation studies conducted in general population and clinical samples [ 6 ], [ 16 ]. These findings suggest that the PHQ-4 maintains stable psychometric performance even in populations experiencing complex psychosocial stressors, such as returned migrant workers. Given the multiple vulnerabilities faced by Cambodian migrants including hazardous work environments, job insecurity and post-migration reintegration challenges the observed reliability supports the PHQ-4’s utility as a brief and robust screening tool in post-migration contexts [ 22 ], [ 23 ]. Factorial validity and dimensional structure A central contribution of this study is the strong support for a two-factor structure, reflecting distinct but correlated anxiety and depression dimensions. This structure aligns with the theoretical conceptualization of the PHQ-4 and with empirical findings from previous studies conducted in diverse cultural settings [ 7 ], [ 10 ], [ 16 ]. While some studies have suggested that a unidimensional psychological distress factor may also be plausible, evidence increasingly supports the two-factor model as offering greater conceptual clarity, particularly when differentiating anxiety and depression symptoms in applied research [ 24 ]. The findings extend this evidence to returned Cambodian migrant workers demonstrating that anxiety and depression remain meaningfully separable constructs despite their high correlation. This distinction is particularly relevant for migrant health research where anxiety and depressive symptoms may have different occupational and social determinants, as well as different implications for intervention and referral pathways. Construct validity and occupational health risks Construct validity of the PHQ-4 was further supported by significant associations between higher PHQ-4 scores and occupational health risk factors, including long working hours, unsafe working conditions and exposure to hazardous environments. These findings are consistent with prior research highlighting the strong relationship between adverse working conditions and poor mental health outcomes among migrant workers [ 23 ], [ 22 ]. The ability of the PHQ-4 to reflect these expected risk gradients suggests that the instrument captures meaningful psychological distress linked to migrants lived experiences rather than nonspecific symptoms [ 25 ]. Contribution to mental health research in Cambodia Although mental health screening tools such as the PHQ-9 and GAD-7 have previously been validated in Cambodian populations [ 26 ], evidence regarding ultra-brief screening instruments has remained limited. The present study extends existing research by demonstrating that the PHQ-4 due to its brevity and strong psychometric performance can serve as a practical alternative in community-based surveys and outreach programs targeting returned migrant workers [ 27 ]. This is particularly important in low-resource settings, where time constraints, stigma and limited access to specialized mental health services may hinder the use of longer instruments. Implications for practice and research The validated PHQ-4 may be a valuable tool for rapid mental health screening, surveillance and referral within migrant reintegration programs and occupational health initiatives in Cambodia. Given the strong support for the two-factor model, future applications may benefit from reporting both anxiety and depression subscale scores in addition to the total score, allowing for more nuanced assessment and targeted interventions. From a public health perspective, the PHQ-4 offers a scalable and low-burden tool for integration into routine screening programs, particularly within migrant reintegration services and occupational health surveillance systems in Cambodia. This aligns with global recommendations to integrate brief screening tools into primary and community health systems, particularly in resource-limited settings. Limitations and future directions Several limitations should be acknowledged. The use of convenience sampling may limit generalizability to all returned migrant workers in Cambodia. Additionally, the absence of a structured clinical diagnostic interview precluded assessment of criterion validity. Future research should examine diagnostic accuracy, test–retest reliability and measurement invariance across key sociodemographic groups to further strengthen the evidence base for PHQ-4 use in Cambodian and regional migrant populations. Additionally, the cross-sectional design precludes causal inference between occupational risk factors and psychological distress. Future longitudinal or prospective studies are warranted to examine temporal relationships and better establish causal pathways. While longer instruments such as the PHQ-9 and GAD-7 are widely used and provide more comprehensive assessment of symptom severity, their length may limit feasibility in large-scale surveys and community-based screening in low- and middle-income countries (LMICs). The PHQ-4, as an ultra-brief instrument, offers a pragmatic alternative for rapid screening with minimal respondent burden. Conclusions This study provides the first validation of the Patient Health Questionnaire-4 (PHQ-4) among returned Cambodian migrant workers. The findings demonstrate acceptable reliability and strong factorial and construct validity, with confirmatory factor analysis supporting a two-factor structure of anxiety and depression. Associations between PHQ-4 scores and occupational health risk factors further support its validity. Given its brevity and psychometric robustness, the PHQ-4 is a practical tool for screening anxiety and depression in community and post-migration settings in Cambodia. This study provides the first evidence supporting the use of PHQ-4 in Cambodia, offering a rapid and scalable screening tool for mental health assessment in migrant populations. Declarations Conflict of Interest The author declares no conflict of interest. Funding This research received no external funding. Clinical Trial Registration Clinical trial number: not applicable. Human Ethics and Consent to Participate This study was approved by the Institutional Review Board of the National Institute of Public Health, Cambodia (IRB No. 269NECHR). All procedures were conducted in accordance with the ethical principles of the Declaration of Helsinki. Written informed consent was obtained from all participants prior to data collection. Consent to Publish Consent to publish not applicable. Data Availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. References ILO World employment and social outlook: Trends 2021, 2021, [Online]. Available: https://www.ilo.org WHO, World Mental Health Report: Transforming Mental Health for All. Geneva: World Health Organization (2022) [Online]. Available: https://www.who.int/publications/i/item/9789240049338 Bates GW, Apputhurai P, Knowles SR (2024) Bivalent Fears of Evaluation in Social Anxiety: Evaluation of an Extended Psychoevolutionary Model., Eur. J. Investig. Health Psychol. Educ. , vol. 14, no. 11, pp. 2918–2931, Nov. 10.3390/ejihpe14110191 Than V, Doroud N, O’Brien L (2024) Mental health service utilization and help seeking behaviours of adult Cambodians living in Western countries: A systematic scoping review., Int. J. Soc. Psychiatry , vol. 70, no. 4, pp. 778–791, Jun. 10.1177/00207640241230848 Sheth N, O’Connor S, Patel S, Dutton MA (2023) To screen or not to screen: Exploring and addressing effective screening processes for trauma among forced migrants. J Migr Health 7:100148. 10.1016/j.jmh.2022.100148 Kroenke K, Spitzer RL, Williams JBW, Löwe B (2009) An Ultra-Brief Screening Scale for Anxiety and Depression: The PHQ-4. Psychosomatics 50(6):613–621 Löwe B et al (2010) A 4-item Measure of Depression and Anxiety: Validation of the PHQ-4 in the General Population. J Affect Disord 122:1–2 Mitchell AJ, Yadegarfar M, Gill J, Stubbs B (2016) Case finding and screening clinical utility of the Patient Health Questionnaire (PHQ-2 and PHQ-9): A meta-analysis of 40 studies. Gen Hosp Psychiatry 39:24–31. 10.1016/j.genhosppsych.2015.12.004 Löwe B, Spitzer RL, Williams JBW, Mussell M, Schellberg D, Kroenke K (2008) Depression, anxiety, and somatization in primary care: Syndrome overlap and functional impairment. Gen Hosp Psychiatry 30(3):191–199. 10.1016/j.genhosppsych.2008.01.001 Staples LG et al (Jan. 2019) Psychometric properties and clinical utility of brief measures of depression, anxiety, and general distress: The PHQ-2, GAD-2, and K-6. Gen Hosp Psychiatry 56:13–18. 10.1016/j.genhosppsych.2018.11.003 Bajre PK (Dec. 2025) Structural validity of the DASS-21 during pandemic-induced psychological distress. Discov Ment Health 6(1). 10.1007/s44192-025-00349-5 Jacobsen G, Casanova MP, Dluzniewski A, Reeves AJ, Baker RT (2024) Examining the Factor Structure and Validity of the Depression Anxiety Stress Scale-21. Eur J Investig Health Psychol Educ 14(11):2932–2943. 10.3390/ejihpe14110192 Hocking DC, Mancuso SG, Sundram S (Mar. 2018) Development and validation of a mental health screening tool for asylum-seekers and refugees: the STAR-MH. BMC Psychiatry 18(1):69. 10.1186/s12888-018-1660-8 Kline RB (2016) Principles and practice of structural equation modeling, 4th edn. Guilford Press Sapra A, Bhandari P, Sharma S, Chanpura T, Lopp L (May 2020) Using Generalized Anxiety Disorder-2 (GAD-2) and GAD-7 in a Primary Care Setting. Cureus 12(5):e8224. 10.7759/cureus.8224 Kroenke K, Spitzer RL, Williams JBW, Lowe B (2009) An ultra-brief screening scale for anxiety and depression: The PHQ-4. Psychosomatics 50(6):613–621. 10.1016/S0033-3182(09)70864-3 WHO Process of translation and adaptation of instruments, 2016, [Online]. Available: https://www.who.int Hu L, Bentler PM (1999) Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Struct Equ Model 6(1):1–55. 10.1080/10705519909540118 Corp IBM (2020) IBM SPSS Amos (Version 27) . IBM Corp. [Online]. Available: https://www.ibm.com/products/spss-amos StataCorp (2021) Stata Statistical Software: Release 17 . StataCorp LLC. [Online]. Available: https://www.stata.com Kroenke K, Williams JBW (2003) The Patient Health Questionnaire-2: Validity of a two-item depression screener. Med Care 41(11):1284–1292. 10.1097/01.MLR.0000093487.78664.3C Apputhurai P, Palsson OS, Bangdiwala SI, Sperber AD, Mikocka-Walus A, Knowles SR (May 2024) Confirmatory validation of the patient health questionnaire – 4 (PHQ-4) for gastrointestinal disorders: A large-scale cross-sectional survey. J Psychosom Res 180:111654. 10.1016/j.jpsychores.2024.111654 Soeparno A, Huda N, Iskandar T (2018) Return migration and mental health among Indonesian workers. Asian Popul Stud 14(3):293–310 Liu Y, Zainal NH (Jul. 2026) Perceived control and long-term depression and anxiety: An 18-year longitudinal mediation study of coping. J Affect Disord 405:121543. 10.1016/j.jad.2026.121543 Kiely B et al (2025) Prevalence of psychological distress detected by the PROTECT and PHQ4 questionnaires and subsequent mental health diagnosis. A cross sectional analysis of the outcomes of new arrival health assessments for refugees and asylum seekers in Ireland. J Migr Health 11:100317. 10.1016/j.jmh.2025.100317 Steinman L et al (2025) Improving recognition of common mental health disorders in Cambodia: Validation of the PHQ-9 and GAD-7 and development of a brief mental health screener. PLOS Ment Health 2(4):e0000228. 10.1371/journal.pmen.0000228 Adzrago D, Walker TJ, Williams F (Mar. 2024) Reliability and validity of the Patient Health Questionnaire-4 scale and its subscales of depression and anxiety among US adults based on nativity. BMC Psychiatry 24(1):213. 10.1186/s12888-024-05665-8 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9228933","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":612372314,"identity":"3965e6e3-b7cb-4d17-84c7-70fd8d97ac0d","order_by":0,"name":"Samphoas Chien","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1UlEQVRIiWNgGAWjYHACNoYEBgY5KIeZgYGHhzgtxiRqAYLEBqK1yDcwP3vwoOJOev+M3GMPGCqsExt4zh7Aq8XgAJu5QcKZZ7kzbuSlGzCcSU9s4O1LwK+FgYdNIrHtcG7DjRwzCca2w4kN/DwGBBwG0vLvcLo8WMs/IrQwHABpaTicYADW0gDUwtuDX4vBYTYziYRjhw03nnmXbpBwLN24jecMAYe1Nz+T/FFzWF7uODDEPtRYy/bz5BBwGDOcxQOOU0g0EQl4SFE8CkbBKBgFIwkAALI+QleQN24NAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0001-4726-0665","institution":"American University of Phnom Penh, Faculty of Social Sciences","correspondingAuthor":true,"prefix":"","firstName":"Samphoas","middleName":"","lastName":"Chien","suffix":""},{"id":612372848,"identity":"3a86219e-9c98-47ac-9b4a-e9be410d8d61","order_by":1,"name":"Kai-Lih Liu","email":"","orcid":"","institution":"Global Health Program, College of Public Health, National Taiwan University, Taiwan","correspondingAuthor":false,"prefix":"","firstName":"Kai-Lih","middleName":"","lastName":"Liu","suffix":""},{"id":612372849,"identity":"2d7c451a-604b-4aad-b0bc-d8e64f5f3f95","order_by":2,"name":"Huyleng Khov","email":"","orcid":"","institution":"University of Health Sciences, Phnom Penh, Cambodia","correspondingAuthor":false,"prefix":"","firstName":"Huyleng","middleName":"","lastName":"Khov","suffix":""},{"id":612372850,"identity":"0804c846-d0e7-43ef-885f-65c94c7310a9","order_by":3,"name":"Chang-Chuan Chan","email":"","orcid":"","institution":"Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taiwan","correspondingAuthor":false,"prefix":"","firstName":"Chang-Chuan","middleName":"","lastName":"Chan","suffix":""}],"badges":[],"createdAt":"2026-03-26 04:05:48","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-9228933/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9228933/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105574638,"identity":"766e8d37-b1f7-4e82-9884-65978e214ada","added_by":"auto","created_at":"2026-03-27 13:35:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":320609,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eOne and Two Factor Confirmatory Factor analysis (CFA)\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9228933/v1/9c8a92c633a9321d6ccabd0e.png"},{"id":105575372,"identity":"022ac6ed-f4a7-4b1f-aa1f-5c273955a6f8","added_by":"auto","created_at":"2026-03-27 13:38:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1031198,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9228933/v1/ba6ecd23-5999-45b8-a7a6-0c48d0b1f959.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003ePsychometric Validation of the Patient Health Questionnaire-4 (PHQ-4) Among Returned Cambodian Migrant Workers\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eInternational labour migration is a defining socio-economic feature of many low- and middle-income countries (LMICs), including Cambodia. Millions of Cambodian workers migrate annually to neighboring countries such as Thailand, Malaysia and the Republic of Korea in search of employment opportunities. While labour migration can improve household income and economic security, migrant workers are frequently exposed to hazardous working conditions, long working hours, job insecurity, social isolation and limited access to health services, all of which increase vulnerability to mental health problems, particularly anxiety and depression [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEvidence suggests that mental health risks do not end upon returning to the country of origin. Returned migrant workers may experience additional stressors, including financial instability, social reintegration difficulties, perceived migration failure and lingering physical or psychological health problems acquired abroad [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In Cambodia, where mental health services remain limited and unevenly distributed, early identification of psychological distress among returned migrants is essential for guiding community-based screening, referral and intervention efforts [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBrief and valid mental health screening tools are particularly important for use among migrant and hard-to-reach populations in resource-constrained settings [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The Patient Health Questionnaire-4 (PHQ-4) is an ultra-brief screening instrument designed to assess core symptoms of anxiety and depression [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It consists of two items derived from the Generalized Anxiety Disorder scale (GAD-2) and two items from the Patient Health Questionnaire depression scale (PHQ-2), yielding both subscale scores and an overall measure of psychological distress [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Due to its brevity and ease of administration, the PHQ-4 has been widely used in primary care, population surveys and epidemiological research [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The use of ultra-brief screening tools has been increasingly recommended for large-scale population surveys and primary care settings due to their feasibility and reduced respondent burden [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePrevious studies have demonstrated that the PHQ-4 possesses good internal consistency, factorial validity and construct validity across diverse populations, including general community samples, clinical settings and occupational groups [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Factor analytic studies generally support either a two-factor structure reflecting distinct but correlated anxiety and depression dimensions or a unidimensional structure representing general psychological distress [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, psychometric properties of mental health instruments may vary across cultural, linguistic and occupational contexts, underscoring the importance of population-specific validation before widespread use [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the growing body of literature on migrant mental health, there remains limited evidence on the psychometric performance of brief screening tools among returned migrant workers in Southeast Asia, particularly in Cambodia [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Up till now, no study has formally validated the PHQ-4 among returned Cambodian migrant workers, a population characterized by unique migration trajectories, occupational exposures and post-migration stressors. Without local validation, the reliability and validity of PHQ-4 scores in this context cannot be assumed. To our knowledge, no study has validated the PHQ-4 in Cambodia or among returned migrant workers in Southeast Asia. Given the increasing need for ultra-brief screening tools in resource-constrained settings, establishing the psychometric performance of PHQ-4 in this context is critical.\u003c/p\u003e \u003cp\u003eConsequently, the present study aimed to evaluate the psychometric properties of the PHQ-4 among returned Cambodian migrant workers. Specifically, this study examined (1) internal consistency reliability, (2) factorial validity by comparing one-factor and two-factor confirmatory factor analytic models and (3) construct validity by assessing associations between PHQ-4 scores and occupational health risk factors. Establishing the validity of the PHQ-4 in this population will support its use as a practical screening tool for anxiety and depression in migration-affected and resource-limited settings.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and setting\u003c/h2\u003e \u003cp\u003eA cross-sectional study was conducted in 2022 among returned Cambodian migrant workers residing in four provinces of Cambodia: Banteay Meanchey, Battambang, Siem Reap and Kampot. These provinces were selected due to their high prevalence of international labour migration and substantial numbers of returned migrant workers. Eligible participants were adults aged 18 years or older who had previously worked abroad and had returned to Cambodia within the past five years. Participants were recruited using a convenience sampling approach through community networks, local authorities and partner organizations working with migrant populations. A total of N\u0026thinsp;=\u0026thinsp;392 returned migrant workers were enrolled in the study. The sample size exceeds recommended thresholds for confirmatory factor analysis, ensuring stable parameter estimation and model fit evaluation [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMeasures\u003c/h3\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003ePatient Health Questionnaire-4\u003c/h2\u003e \u003cp\u003eMental health symptoms were assessed using the Patient Health Questionnaire-4 (PHQ-4), an ultra-brief screening instrument designed to measure core symptoms of anxiety and depression over the preceding two weeks. The PHQ-4 comprises four items, each rated on a 4-point Likert scale ranging from 0 (\u0026ldquo;not at all\u0026rdquo;) to 3 (\u0026ldquo;nearly every day\u0026rdquo;), producing a total score between 0 and 12, with higher scores indicating greater psychological distress. The instrument consists of two subscales: the anxiety subscale (items 1\u0026ndash;2), derived from the Generalized Anxiety Disorder-2 (GAD-2) [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], and the depression subscale (items 3\u0026ndash;4), derived from the Patient Health Questionnaire-2 (PHQ-2) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The PHQ-4 has demonstrated good reliability and construct validity across diverse populations and cultural settings, including general population samples and clinical contexts [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Its brevity and strong psychometric performance make it particularly suitable for use among migrant and hard-to-reach populations in low- and middle-income countries, where time constraints and limited access to mental health services are common.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eTranslation procedure\u003c/h3\u003e\n\u003cp\u003eFor the present study, PHQ-4 was administered in the Khmer language. The instrument was translated from English into Khmer and subsequently back translated by independent bilingual experts to ensure conceptual and semantic equivalence. Discrepancies were resolved through consensus discussion, following established cross-cultural adaptation guidelines for psychometric instruments [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eInternal consistency reliability of the PHQ-4 and its subscales was assessed using Cronbach\u0026rsquo;s alpha coefficients. Confirmatory factor analysis (CFA) was performed using maximum likelihood estimation to examine the factorial structure of the PHQ-4 by comparing a one-factor model representing general psychological distress with a two-factor model reflecting correlated anxiety and depression dimensions. Model fit was evaluated using multiple goodness-of-fit indices, including the Comparative Fit Index (CFI), Tucker\u0026ndash;Lewis Index (TLI), Root Mean Square Error of Approximation (RMSEA) and the Standardized Root Mean Square Residual (SRMR). Model adequacy was determined based on commonly accepted criteria, with CFI and TLI values\u0026thinsp;\u0026ge;\u0026thinsp;0.95, RMSEA\u0026thinsp;\u0026le;\u0026thinsp;0.06, and SRMR\u0026thinsp;\u0026le;\u0026thinsp;0.08 indicating good fit [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Construct validity was examined by assessing associations between PHQ-4 scores and selected occupational health risk factors, including long working hours, unsafe working conditions and exposure to hazardous work environments. Multivariate logistic regression analyses were conducted to estimate adjusted odds ratios (AORs) and corresponding 95% confidence intervals, controlling for relevant sociodemographic characteristics, Statistical significance was set at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05. All statistical analyses were conducted using Stata version 17 (StataCorp, College Station, TX, USA) and SPSS AMOS Graphics version 27 (IBM Corp., Armonk, NY, USA) [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e This study was approved by the Institutional Review Board of the National Institute of Public Health, Cambodia (IRB No. 269NECHR). All procedures were conducted in accordance with the ethical principles of the Declaration of Helsinki. Written informed consent was obtained from all participants prior to data collection and confidentiality, and anonymity were strictly maintained throughout the study.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eParticipant characteristics\u003c/h2\u003e \u003cp\u003eThe mean age of participants was 34.7 years (SD\u0026thinsp;=\u0026thinsp;8.9). Approximately 52% were male and 48% female. Most participants had previously worked in construction, agriculture and domestic work sectors. The mean PHQ-4 score was 2.13 (SD\u0026thinsp;=\u0026thinsp;2.24), with the majority reporting none to mild psychological distress.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eReliability\u003c/h3\u003e\n\u003cp\u003eThe PHQ-4 demonstrated acceptable internal consistency reliability. The anxiety subscale yielded a Cronbach\u0026rsquo;s (α\u0026thinsp;=\u0026thinsp;0.78), while the depression subscale demonstrated a Cronbach\u0026rsquo;s alpha α\u0026thinsp;=\u0026thinsp;0.73. These findings indicate satisfactory reliability of the total scale and subscales.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eFactorial validity (CFA models)\u003c/h2\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003eOne-factor model\u003c/h2\u003e \u003cp\u003eA one-factor confirmatory factor analysis (CFA) was conducted on the four-item PHQ-4 scale, hypothesizing that all items reflect a single latent construct representing general psychological distress. The model showed adequate to good fit based on common indices: \u003cem\u003eCFI\u0026thinsp;=\u0026thinsp;0.97, TLI\u0026thinsp;=\u0026thinsp;0.95, RMSEA\u0026thinsp;=\u0026thinsp;0.055 (90% CI\u0026thinsp;=\u0026thinsp;0.00\u0026ndash;0.11), SRMR\u0026thinsp;=\u0026thinsp;0.028\u003c/em\u003e. All items loaded significantly on the latent factor, with standardized loadings ranging from 0.59\u0026ndash;0.71. Specifically, \u0026ldquo;Nervousness\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.71) and \u0026ldquo;Worries\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.68) had slightly stronger loadings compared to \u0026ldquo;Loss of interest\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.62) and \u0026ldquo;Depressive mood\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.59).\u003c/p\u003e \u003cp\u003eThe latent factor accounted for approximately 49%-65% of the variance in individual items, as indicated by residual error variances. The overall internal consistency of the scale was acceptable (α\u0026thinsp;=\u0026thinsp;0.78). These findings support the interpretation of PHQ-4 as a unidimensional measure of general emotional distress in this sample.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eModel Fit Indices for One-Factor and Two-Factor CFA Models\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eModel\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eSB χ\u0026sup2;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003edf\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eCFI\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eTLI\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eNFI\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eRMSEA\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003eχ\u0026sup2;\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ep-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOne-factor model\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1960.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e938.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTwo-factor model\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e\u003cb\u003eNote.\u003c/b\u003e \u003cem\u003eSB χ\u0026sup2; = Satorra-Bentler scaled chi-square; df\u0026thinsp;=\u0026thinsp;degrees of freedom; CFI\u0026thinsp;=\u0026thinsp;Comparative Fit Index; TLI\u0026thinsp;=\u0026thinsp;Tucker-Lewis Index; NFI\u0026thinsp;=\u0026thinsp;Normed Fit Index; RMSEA\u0026thinsp;=\u0026thinsp;Root Mean Square Error of Approximation. A lower RMSEA (\u0026lt;\u0026thinsp;0.06); and higher CFI/TLI (\u0026gt;\u0026thinsp;0.95), indicate good model fit. The Δχ\u0026sup2; test compares the nested models.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eTwo-factor model\u003c/h2\u003e \u003cp\u003eA two-factor confirmatory factor analysis (CFA) was conducted to examine the dimensional structure of the PHQ-4, specifying separate but correlated latent factors for anxiety (measured by \u0026ldquo;Nervousness\u0026rdquo; and \u0026ldquo;Worries\u0026rdquo;) and depression (measured by \u0026ldquo;Loss of interest\u0026rdquo; and \u0026ldquo;Depressive mood\u0026rdquo;). The model demonstrated excellent fit to the data based on the following indices: CFI\u0026thinsp;=\u0026thinsp;0.99, TLI\u0026thinsp;=\u0026thinsp;0.98, RMSEA\u0026thinsp;=\u0026thinsp;0.035 (90% CI\u0026thinsp;=\u0026thinsp;0.00\u0026ndash;0.09), SRMR\u0026thinsp;=\u0026thinsp;0.016\u003c/p\u003e \u003cp\u003eStandardized factor loadings were all strong and statistically significant (λ\u0026thinsp;=\u0026thinsp;0.68\u0026ndash;0.81). The anxiety items loaded onto their factor as follows: \u0026ldquo;Nervousness\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.71), \u0026ldquo;Worries\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.68); and the depression items: \u0026ldquo;Loss of interest\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.62), \u0026ldquo;Depressive mood\u0026rdquo; (λ\u0026thinsp;=\u0026thinsp;0.59). The two latent factors were strongly correlated, r\u0026thinsp;=\u0026thinsp;0.79, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, indicating substantial overlap between symptoms of anxiety and depression.\u003c/p\u003e \u003cp\u003eResidual error variances ranged from 0.35\u0026ndash;0.51, suggesting that each latent factor accounted for approximately 49%-65% of its indicators\u0026rsquo; variance. Internal consistency was high for both subscales (α\u0026thinsp;=\u0026thinsp;0.78 for anxiety; α\u0026thinsp;=\u0026thinsp;0.80 for depression).\u003c/p\u003e \u003cp\u003eThese results support a two-factor structure of the PHQ-4, consistent with its original conceptualization. This model may offer better construct precision than a unidimensional structure, particularly in analyses aiming to differentiate anxiety from depression symptoms.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eConstruct psychometric validation\u003c/h2\u003e \u003cp\u003eDescriptive analysis showed low mean distress (M\u0026thinsp;=\u0026thinsp;2.13, SD\u0026thinsp;=\u0026thinsp;2.24), with most participants falling into the \u0026ldquo;none\u0026rdquo; or \u0026ldquo;mild\u0026rdquo; severity categories. Construct validity of the PHQ-4 was examined by assessing associations between PHQ-4 scores and selected occupational health risk factors.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eItem Loadings on Two-Factor Structure of Anxiety and Depression\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eItem\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eFactor 1 (Anxiety)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eFactor 2 (Depression)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNervousness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWorries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLoss of interest\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDepressive mood\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.59\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003e\u003cb\u003eNote.\u003c/b\u003e \u003cem\u003eFactor loadings are standardized estimates from the two-factor confirmatory factor analysis (CFA) of PHQ-4. All loadings are significant at p\u0026thinsp;\u0026lt;\u0026thinsp;0.001.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eConstruct Validity\u003c/h2\u003e \u003cp\u003eA multivariate logistic regression analysis was conducted to examine the association between occupational risk factors and psychological distress measured by the PHQ-4. The results indicated that several occupational exposures were significantly associated with higher odds of psychological distress among returned Cambodian migrant workers. Specifically, individuals who reported long working hours had significantly greater odds of experiencing psychological distress compared with those working standard hours (AOR\u0026thinsp;=\u0026thinsp;1.45, 95% CI [1.10, 1.92], \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008). Similarly, exposure to unsafe working conditions was associated with increased odds of psychological distress (AOR\u0026thinsp;=\u0026thinsp;1.63, 95% CI [1.21, 2.20], \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002). Workers exposed to hazardous environments also had higher odds of psychological distress (AOR\u0026thinsp;=\u0026thinsp;1.38, 95% CI [1.05, 1.82], \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.021).\u003c/p\u003e \u003cp\u003eIn contrast, demographic characteristics such as sex (AOR\u0026thinsp;=\u0026thinsp;0.92, 95% CI [0.68, 1.25], \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.60) and age (AOR\u0026thinsp;=\u0026thinsp;1.01, 95% CI [0.98, 1.03], \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.42) were not significantly associated with psychological distress. These findings provide evidence supporting the construct validity of the PHQ-4, as higher psychological distress scores were associated with occupational risk factors known to adversely affect migrant workers\u0026rsquo; mental health.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMultivariate Logistic Regression Analysis of Factors Associated with Psychological Distress (PHQ-4)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eVariable\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAOR\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003e95% CI\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003ep-value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLong working hours (\u0026gt;\u0026thinsp;8 hours/day)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.10\u0026ndash;1.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnsafe working conditions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.21\u0026ndash;2.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHazardous work exposure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.05\u0026ndash;1.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale (vs female)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.68\u0026ndash;1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.600\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.98\u0026ndash;1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.420\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConstruction sector (vs other sectors)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.95\u0026ndash;1.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cem\u003eNote: AOR\u0026thinsp;=\u0026thinsp;Adjusted Odds Ratio; CI\u0026thinsp;=\u0026thinsp;Confidence Interval. The model was adjusted for age, sex and employment sector. Statistical significance was defined as p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study provides the first psychometric validation of the Patient Health Questionnaire-4 (PHQ-4) among returned Cambodian migrant workers, addressing a critical gap in Cambodia\u0026rsquo;s mental health measurement landscape. Overall, the findings support the reliability, factorial validity and construct validity of the PHQ-4 in this population, indicating that the instrument is appropriate for screening anxiety and depression symptoms among migrants returning from overseas employment. The internal consistency in this sample was high (α\u0026thinsp;=\u0026thinsp;0.78 for anxiety; α\u0026thinsp;=\u0026thinsp;0.80 for depression), consistent with findings from other cross-national studies. Kroenke and Williams (2009) demonstrated that the PHQ-4 is a reliable and efficient screening tool for identifying anxiety and depression in primary care settings. It performs comparably to longer measures in terms of construct validity and effectively identifies patients who may require further evaluation for clinical disorders [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Further demonstrated that the PHQ-4 is a psychometrically robust ultra-brief screening tool with strong construct validity, validated in a large German general population sample [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Its high internal consistency (α\u0026thinsp;=\u0026thinsp;0.82), construct validity and associations with known risk factors (gender, age, education, income, partnership status) support its use in clinical settings.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eStrengths and limitations\u003c/h2\u003e \u003cp\u003eThe PHQ-4 demonstrated acceptable internal consistency in this study, comparable to levels reported in international validation studies conducted in general population and clinical samples [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. These findings suggest that the PHQ-4 maintains stable psychometric performance even in populations experiencing complex psychosocial stressors, such as returned migrant workers. Given the multiple vulnerabilities faced by Cambodian migrants including hazardous work environments, job insecurity and post-migration reintegration challenges the observed reliability supports the PHQ-4\u0026rsquo;s utility as a brief and robust screening tool in post-migration contexts [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eFactorial validity and dimensional structure\u003c/h2\u003e \u003cp\u003eA central contribution of this study is the strong support for a two-factor structure, reflecting distinct but correlated anxiety and depression dimensions. This structure aligns with the theoretical conceptualization of the PHQ-4 and with empirical findings from previous studies conducted in diverse cultural settings [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. While some studies have suggested that a unidimensional psychological distress factor may also be plausible, evidence increasingly supports the two-factor model as offering greater conceptual clarity, particularly when differentiating anxiety and depression symptoms in applied research [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The findings extend this evidence to returned Cambodian migrant workers demonstrating that anxiety and depression remain meaningfully separable constructs despite their high correlation. This distinction is particularly relevant for migrant health research where anxiety and depressive symptoms may have different occupational and social determinants, as well as different implications for intervention and referral pathways.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eConstruct validity and occupational health risks\u003c/h2\u003e \u003cp\u003eConstruct validity of the PHQ-4 was further supported by significant associations between higher PHQ-4 scores and occupational health risk factors, including long working hours, unsafe working conditions and exposure to hazardous environments. These findings are consistent with prior research highlighting the strong relationship between adverse working conditions and poor mental health outcomes among migrant workers [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The ability of the PHQ-4 to reflect these expected risk gradients suggests that the instrument captures meaningful psychological distress linked to migrants lived experiences rather than nonspecific symptoms [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eContribution to mental health research in Cambodia\u003c/h2\u003e \u003cp\u003eAlthough mental health screening tools such as the PHQ-9 and GAD-7 have previously been validated in Cambodian populations [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], evidence regarding ultra-brief screening instruments has remained limited. The present study extends existing research by demonstrating that the PHQ-4 due to its brevity and strong psychometric performance can serve as a practical alternative in community-based surveys and outreach programs targeting returned migrant workers [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This is particularly important in low-resource settings, where time constraints, stigma and limited access to specialized mental health services may hinder the use of longer instruments.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eImplications for practice and research\u003c/h2\u003e \u003cp\u003eThe validated PHQ-4 may be a valuable tool for rapid mental health screening, surveillance and referral within migrant reintegration programs and occupational health initiatives in Cambodia. Given the strong support for the two-factor model, future applications may benefit from reporting both anxiety and depression subscale scores in addition to the total score, allowing for more nuanced assessment and targeted interventions. From a public health perspective, the PHQ-4 offers a scalable and low-burden tool for integration into routine screening programs, particularly within migrant reintegration services and occupational health surveillance systems in Cambodia. This aligns with global recommendations to integrate brief screening tools into primary and community health systems, particularly in resource-limited settings.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eLimitations and future directions\u003c/h2\u003e \u003cp\u003eSeveral limitations should be acknowledged. The use of convenience sampling may limit generalizability to all returned migrant workers in Cambodia. Additionally, the absence of a structured clinical diagnostic interview precluded assessment of criterion validity. Future research should examine diagnostic accuracy, test\u0026ndash;retest reliability and measurement invariance across key sociodemographic groups to further strengthen the evidence base for PHQ-4 use in Cambodian and regional migrant populations.\u003c/p\u003e \u003cp\u003eAdditionally, the cross-sectional design precludes causal inference between occupational risk factors and psychological distress. Future longitudinal or prospective studies are warranted to examine temporal relationships and better establish causal pathways.\u003c/p\u003e \u003cp\u003eWhile longer instruments such as the PHQ-9 and GAD-7 are widely used and provide more comprehensive assessment of symptom severity, their length may limit feasibility in large-scale surveys and community-based screening in low- and middle-income countries (LMICs). The PHQ-4, as an ultra-brief instrument, offers a pragmatic alternative for rapid screening with minimal respondent burden.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study provides the first validation of the Patient Health Questionnaire-4 (PHQ-4) among returned Cambodian migrant workers. The findings demonstrate acceptable reliability and strong factorial and construct validity, with confirmatory factor analysis supporting a two-factor structure of anxiety and depression. Associations between PHQ-4 scores and occupational health risk factors further support its validity. Given its brevity and psychometric robustness, the PHQ-4 is a practical tool for screening anxiety and depression in community and post-migration settings in Cambodia. This study provides the first evidence supporting the use of PHQ-4 in Cambodia, offering a rapid and scalable screening tool for mental health assessment in migrant populations.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author declares no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinical trial number: not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHuman Ethics and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board of the National Institute of Public Health, Cambodia (IRB No. 269NECHR). All procedures were conducted in accordance with the ethical principles of the Declaration of Helsinki. Written informed consent was obtained from all participants prior to data collection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConsent to publish not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eILO World employment and social outlook: Trends 2021, 2021, [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ilo.org\u003c/span\u003e\u003cspan address=\"https://www.ilo.org\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO, World Mental Health Report: Transforming Mental Health for All. Geneva: World Health Organization (2022) [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.who.int/publications/i/item/9789240049338\u003c/span\u003e\u003cspan address=\"https://www.who.int/publications/i/item/9789240049338\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBates GW, Apputhurai P, Knowles SR (2024) Bivalent Fears of Evaluation in Social Anxiety: Evaluation of an Extended Psychoevolutionary Model., \u003cem\u003eEur. J. Investig. Health Psychol. Educ.\u003c/em\u003e, vol. 14, no. 11, pp. 2918\u0026ndash;2931, Nov. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/ejihpe14110191\u003c/span\u003e\u003cspan address=\"10.3390/ejihpe14110191\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThan V, Doroud N, O\u0026rsquo;Brien L (2024) Mental health service utilization and help seeking behaviours of adult Cambodians living in Western countries: A systematic scoping review., \u003cem\u003eInt. J. Soc. Psychiatry\u003c/em\u003e, vol. 70, no. 4, pp. 778\u0026ndash;791, Jun. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/00207640241230848\u003c/span\u003e\u003cspan address=\"10.1177/00207640241230848\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSheth N, O\u0026rsquo;Connor S, Patel S, Dutton MA (2023) To screen or not to screen: Exploring and addressing effective screening processes for trauma among forced migrants. J Migr Health 7:100148. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jmh.2022.100148\u003c/span\u003e\u003cspan address=\"10.1016/j.jmh.2022.100148\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKroenke K, Spitzer RL, Williams JBW, L\u0026ouml;we B (2009) An Ultra-Brief Screening Scale for Anxiety and Depression: The PHQ-4. Psychosomatics 50(6):613\u0026ndash;621\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026ouml;we B et al (2010) A 4-item Measure of Depression and Anxiety: Validation of the PHQ-4 in the General Population. J Affect Disord 122:1\u0026ndash;2\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMitchell AJ, Yadegarfar M, Gill J, Stubbs B (2016) Case finding and screening clinical utility of the Patient Health Questionnaire (PHQ-2 and PHQ-9): A meta-analysis of 40 studies. Gen Hosp Psychiatry 39:24\u0026ndash;31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.genhosppsych.2015.12.004\u003c/span\u003e\u003cspan address=\"10.1016/j.genhosppsych.2015.12.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL\u0026ouml;we B, Spitzer RL, Williams JBW, Mussell M, Schellberg D, Kroenke K (2008) Depression, anxiety, and somatization in primary care: Syndrome overlap and functional impairment. Gen Hosp Psychiatry 30(3):191\u0026ndash;199. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.genhosppsych.2008.01.001\u003c/span\u003e\u003cspan address=\"10.1016/j.genhosppsych.2008.01.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStaples LG et al (Jan. 2019) Psychometric properties and clinical utility of brief measures of depression, anxiety, and general distress: The PHQ-2, GAD-2, and K-6. Gen Hosp Psychiatry 56:13\u0026ndash;18. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.genhosppsych.2018.11.003\u003c/span\u003e\u003cspan address=\"10.1016/j.genhosppsych.2018.11.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBajre PK (Dec. 2025) Structural validity of the DASS-21 during pandemic-induced psychological distress. Discov Ment Health 6(1). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s44192-025-00349-5\u003c/span\u003e\u003cspan address=\"10.1007/s44192-025-00349-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJacobsen G, Casanova MP, Dluzniewski A, Reeves AJ, Baker RT (2024) Examining the Factor Structure and Validity of the Depression Anxiety Stress Scale-21. Eur J Investig Health Psychol Educ 14(11):2932\u0026ndash;2943. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/ejihpe14110192\u003c/span\u003e\u003cspan address=\"10.3390/ejihpe14110192\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHocking DC, Mancuso SG, Sundram S (Mar. 2018) Development and validation of a mental health screening tool for asylum-seekers and refugees: the STAR-MH. BMC Psychiatry 18(1):69. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12888-018-1660-8\u003c/span\u003e\u003cspan address=\"10.1186/s12888-018-1660-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKline RB (2016) Principles and practice of structural equation modeling, 4th edn. Guilford Press\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSapra A, Bhandari P, Sharma S, Chanpura T, Lopp L (May 2020) Using Generalized Anxiety Disorder-2 (GAD-2) and GAD-7 in a Primary Care Setting. Cureus 12(5):e8224. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.7759/cureus.8224\u003c/span\u003e\u003cspan address=\"10.7759/cureus.8224\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKroenke K, Spitzer RL, Williams JBW, Lowe B (2009) An ultra-brief screening scale for anxiety and depression: The PHQ-4. Psychosomatics 50(6):613\u0026ndash;621. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0033-3182(09)70864-3\u003c/span\u003e\u003cspan address=\"10.1016/S0033-3182(09)70864-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO Process of translation and adaptation of instruments, 2016, [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.who.int\u003c/span\u003e\u003cspan address=\"https://www.who.int\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu L, Bentler PM (1999) Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Struct Equ Model 6(1):1\u0026ndash;55. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1080/10705519909540118\u003c/span\u003e\u003cspan address=\"10.1080/10705519909540118\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCorp IBM (2020) \u003cem\u003eIBM SPSS Amos (Version 27)\u003c/em\u003e. IBM Corp. [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ibm.com/products/spss-amos\u003c/span\u003e\u003cspan address=\"https://www.ibm.com/products/spss-amos\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStataCorp (2021) \u003cem\u003eStata Statistical Software: Release 17\u003c/em\u003e. StataCorp LLC. [Online]. Available: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.stata.com\u003c/span\u003e\u003cspan address=\"https://www.stata.com\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKroenke K, Williams JBW (2003) The Patient Health Questionnaire-2: Validity of a two-item depression screener. Med Care 41(11):1284\u0026ndash;1292. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.MLR.0000093487.78664.3C\u003c/span\u003e\u003cspan address=\"10.1097/01.MLR.0000093487.78664.3C\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eApputhurai P, Palsson OS, Bangdiwala SI, Sperber AD, Mikocka-Walus A, Knowles SR (May 2024) Confirmatory validation of the patient health questionnaire\u0026thinsp;\u0026ndash;\u0026thinsp;4 (PHQ-4) for gastrointestinal disorders: A large-scale cross-sectional survey. J Psychosom Res 180:111654. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jpsychores.2024.111654\u003c/span\u003e\u003cspan address=\"10.1016/j.jpsychores.2024.111654\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoeparno A, Huda N, Iskandar T (2018) Return migration and mental health among Indonesian workers. Asian Popul Stud 14(3):293\u0026ndash;310\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Y, Zainal NH (Jul. 2026) Perceived control and long-term depression and anxiety: An 18-year longitudinal mediation study of coping. J Affect Disord 405:121543. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jad.2026.121543\u003c/span\u003e\u003cspan address=\"10.1016/j.jad.2026.121543\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKiely B et al (2025) Prevalence of psychological distress detected by the PROTECT and PHQ4 questionnaires and subsequent mental health diagnosis. A cross sectional analysis of the outcomes of new arrival health assessments for refugees and asylum seekers in Ireland. J Migr Health 11:100317. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jmh.2025.100317\u003c/span\u003e\u003cspan address=\"10.1016/j.jmh.2025.100317\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSteinman L et al (2025) Improving recognition of common mental health disorders in Cambodia: Validation of the PHQ-9 and GAD-7 and development of a brief mental health screener. PLOS Ment Health 2(4):e0000228. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pmen.0000228\u003c/span\u003e\u003cspan address=\"10.1371/journal.pmen.0000228\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdzrago D, Walker TJ, Williams F (Mar. 2024) Reliability and validity of the Patient Health Questionnaire-4 scale and its subscales of depression and anxiety among US adults based on nativity. BMC Psychiatry 24(1):213. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12888-024-05665-8\u003c/span\u003e\u003cspan address=\"10.1186/s12888-024-05665-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"PHQ-4, psychometric validation, migrant workers, anxiety, depression, confirmatory factor analysis, Cambodia","lastPublishedDoi":"10.21203/rs.3.rs-9228933/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9228933/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUltra-brief mental health screening tools are increasingly needed for use in large-scale surveys and resource-constrained settings, particularly among migrant populations in low- and middle-income countries (LMICs). The Patient Health Questionnaire-4 (PHQ-4) is a widely used instrument for assessing anxiety and depression; however, its psychometric properties have not been validated among returned migrant workers in Cambodia.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA cross-sectional study was conducted among 392 returned Cambodian migrant workers recruited from four provinces in 2022. Internal consistency was assessed using Cronbach’s alpha. Confirmatory factor analysis (CFA) was performed to compare one-factor and two-factor models. Construct validity was evaluated by examining associations between PHQ-4 scores and occupational health risk factors using multivariate logistic regression.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe PHQ-4 demonstrated acceptable internal consistency (α = 0.78). CFA supported a two-factor structure representing anxiety and depression, which showed superior model fit compared to the one-factor model (CFI = 0.97, TLI = 0.95, RMSEA = 0.05, SRMR = 0.03). The two factors were moderately correlated (r = 0.63). Higher PHQ-4 scores were significantly associated with long working hours (AOR = 1.45, 95% CI: 1.10–1.92), unsafe working conditions (AOR = 1.63, 95% CI: 1.21–2.20), and hazardous work exposure (AOR = 1.38, 95% CI: 1.05–1.82), supporting construct validity.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe PHQ-4 is a reliable and valid ultra-brief screening tool for assessing anxiety and depression among returned Cambodian migrant workers. Its brevity and strong psychometric performance support its use in large-scale surveys, occupational health assessments, and community-based mental health screening in migration-affected populations in LMICs.\u003c/p\u003e","manuscriptTitle":"Psychometric Validation of the Patient Health Questionnaire-4 (PHQ-4) Among Returned Cambodian Migrant Workers","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-27 13:03:45","doi":"10.21203/rs.3.rs-9228933/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1f4e2d04-2982-40fe-a280-50baa2d65055","owner":[],"postedDate":"March 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":65159348,"name":"Psychology"}],"tags":[],"updatedAt":"2026-03-27T13:03:45+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-27 13:03:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9228933","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9228933","identity":"rs-9228933","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}