The Turkish Validation of the Expanded Prostate Cancer Index Composite (Epic) in Prostate Cancer Patients

The Turkish Validation of the Expanded Prostate Cancer Index Composite (Epic) in Prostate Cancer Patients | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The Turkish Validation of the Expanded Prostate Cancer Index Composite (Epic) in Prostate Cancer Patients Burak Tilki, Pervin Hurmuz, Deniz Yuce, Gokhan Ozyigit, Fadil Akyol This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4399475/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: The Expanded Prostate Cancer Index Composite (EPIC) is a symptom scale that measures health-related quality of life (HRQoL) in prostate cancer (PCa) patients. This scale is translated into different languages and used in daily practice. This study aimed to translate the EPIC scale into Turkish and provide Turkish validation by conducting validity and reliability analyses. Methods: Patients with biopsy-proven PCa who received definitive or postoperative radiotherapy (RT) at our department were included. All participants were evaluated using the Turkish EPIC, The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ) C30, and EORTC-QLQ PR25 questionnaires at five different time intervals. First, the original English version of the EPIC was translated into Turkish, and then, two reliability and five validity analyses were performed. Results: One hundred-five patients were included in the study. In the reliability analyses, Cronbach's alpha values of the whole scale were measured at 0.866, and the main scales' Cronbach's alpha values were measured between 0.654 and 0.969. In the test-retest analysis, the correlation values of the main scales were measured between 0.413 and 0.861. The pilot study with 20 patients was completed, thus providing face validity. Sensitivity to change analysis, interscale correlation, criterion validity, and explanatory factor analyses were performed, and results proving the scale's validity were obtained in all analyses. Conclusion: The Turkish EPIC scale is applicable for patients in the Turkish population diagnosed with PCa who received either definitive or postoperative RT. Quality of Life Prostate Cancer Radiotherapy Validation Study Stereotactic Body Radiotherapy Figures Figure 1 INTRODUCTION Prostate cancer (PCa) is the most common and the second lethal cancer among men worldwide [1]. Approximately 19,450 new PCa cases were diagnosed in Turkey in 2020, and it is estimated that about 5,500 patients may die annually due to PCa [2]. Depending on the stage of the disease, several treatment methods such as radical prostatectomy (RP), external beam radiotherapy (EBRT), brachytherapy (BRT), active surveillance, androgen deprivation therapy (ADT), and chemotherapy are used alone or in combination [3]. Radiotherapy (RT) is one of the main treatment options for PCa and has a wide range of uses from the early to the metastatic stage. However, RT when alone or combined with other treatments has gastrointestinal system (GIS), genitourinary system (GUS), sexual and hormonal side effects and these complications may cause significant effects on patients’ health-related quality of life (HRQoL). Especially in localized PCa, 10-year survival rates reach over 80% [4]. In this patient group with a long life expectancy, the possible side effects of the treatments may come to the forefront in the patients’ lives, which may affect their HRQoL. Many studies examine HRQoL in PCa patients, and many scales have been developed to measure HRQoL. Expanded Prostate Index Composite (EPIC) was developed and validated in 2000 as a more comprehensive version of the University of California Los Angeles-Prostate Cancer Index (UCLA-PCI) questionnaire [5, 6]. In this scale, patients' complaints about RP, ERT, BRT, and ADT were evaluated in the light of the literature. The original English scale comprised 50 questions encompassing four main domains: urinary, bowel, sexual and hormonal. The EPIC has been translated and validated in several other languages (i.e., German, French, Korean, Brazilian, Japanese) [7-12]. In addition, two abbreviated versions of the EPIC have been created and validated (EPIC-26 and EPIC-CP) [13, 14]. To our knowledge, there is no Turkish translation and ours is the first study to translate and validate the Turkish version of EPIC. In this context, this study aimed to translate and validate the Turkish version of the original EPIC questionnaire. MATERIALS AND METHODS Study Population Patients previously diagnosed with biopsy-proven PCa and received RT at our department between 01.06.2019 and 01.12.2021 were accrued in this study. Patients with biopsy-proven PCa aged ≥ 18 years, diagnosed with T1-4N0M0 tumor according to American Joint Commission on Cancer (AJCC) 8th edition, receiving adjuvant or salvage RT after RP or being treated with definitive RT, with Karnofsky Performance Score (KPS) ≥ 70 were included in this study. Patients with distant metastasis, lymph node involvement, previous pelvic RT, transurethral resection and cancer history were excluded. Informed consent was obtained from all patients at the beginning of the study. Approval for the study was obtained from Hacettepe University Non-Interventional Clinical Research Ethics Committee on April 2, 2019, with registration number GO 19/331 and conducted by the Declaration of Helsinki. Study Procedure The patients were evaluated using the Turkish EPIC, EORTC-QLQ C30, and EORTC-QLQ PR25 questionnaires at different time intervals. Patients were asked to fulfill the questionnaires before RT (baseline-T 1 ), 2-4 weeks after the initiation of RT (second assessment-T 2 ), three (T 3 ), six (T 4 ), and twelve (T 5 ) months follow-up visits. Patients were given both face-to-face and solitary applications, and their responses were documented on questionnaire forms and stored in a database. The data of the patients who completed the baseline and second assessment questionnaires were examined for reliability and validity analyses. The patients data who completed all the questionnaires were analyzed for sensitivity to change analysis. The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ) C30 contains 30 items and assesses eight symptom scales as fatigue, nausea and vomiting, pain, dyspnea, insomnia, appetite loss, constipation, and diarrhea, five functional scales as physical, role, emotional, cognitive, and social functioning, global health status (GHS), and financial difficulties [15]. For each scale, a separate score is produced. Scores vary from 0 (worst) to 100 (best) for the functional scales and GHS and from 0 (best) to 100 (worst) for the symptom scales and were generated according to the EORTC Scoring Manual. The 25 items in the EORTC-QLQ PR25 module measure two functional scales (sexual activity and sexual functioning) and four symptomatic scales (urinary symptoms, bowel symptoms, hormone treatment-related symptoms, and incontinence aid) that are all unique to PCa [16]. This module was required along with completing the QLQ-C30 questionnaire. Like the QLQ-C30, a single score is created for each measure and standardized on a 0-100 scale, where a high score denotes a high symptomatology or functional impairment level. Translation and Cultural Adaptation of the Turkish Version of EPIC Translation and cultural adaptation of the Turkish Version of EPIC were performed according to ISPOR Task Force Group recommendations [17]. Two proficient translators independently translated the original English EPIC questionnaire from English to Turkish followed by a separate evaluation by another researcher with an exceptional level of English, and the first Turkish form of the questionnaire was created. Another professional translator translated the completed survey from Turkish to English. All researchers participating in the study made final corrections in the translation, considering the linguistic and cultural differences between the original form and the Turkish translation. Afterward, a pilot study was conducted in 20 patients. In the pilot study, patients were asked which questions they had difficulty in understanding after the face-to-face survey study. When the patients received no negative feedback, the final version of the Turkish form was considered complete (Supplementary File S 1) . Statistical Analyses For continuous variables, mean ± standard deviation (SD) or median (interquartile range-IQR) and number (%) are used to characterize the patients' baseline sociodemographic and clinical features. Two measures were used to assess the reliability of the instruments; internal consistency and test-retest reliability. The Cronbach's alpha test was used to evaluate the scale's internal consistency, which produces a coefficient between 0 and 1. An acceptable coefficient range for reliability analysis is between 0.70-0.95 [18]. The test-retest reliability method measures the consistency of responses to repeated measures of the same questionnaires. To minimize the effect of possible confounding variables, such as recovery and learning effects, a two-week interval was considered as the optimal time duration for the retest [19]. The intraclass correlation coefficient (ICC) was used to evaluate test-retest reliability, and interscale correlations and correlations between EPIC, EORTC-QLQ C30, and EORTC-QLQ PR25 were assessed using Spearman correlation coefficients (r), which indicates the strength of the relationship between two variables. Relationships between 0.00 and 0.10 were considered negligible, while relationships between 0.10 and 0.30 were considered weak correlations. Relationships between 0.30-0.69 were considered moderate, 0.70-0.89 were considered strong, and 0.90-1.00 were considered very strong correlations. The type 1 error was used at 5% for statistical significance. Face validity, in which the pilot study was conducted with 20 patients, was evaluated and first assessed to investigate the study's validity. Subsequently, the change in HRQoL scores of the questionnaires administered at five different times was analyzed using the sensitivity to change method. The relationship between subscales was evaluated with interscale correlation analysis. Criterion validity analysis was performed by comparing the results of the EORTC-QLQ C30 and PR25 scales with the results of the Turkish EPIC scale. Finally, exploratory factor analyses were performed for the scale's factor structure during the validation process. The desired factor load value in factor analysis is values greater than 0.30. The study was analyzed with SPSS v.23 (IBM Corp., Armonk, NY, USA) software. RESULTS A total of 105 patients were included in the study. Around 97% of the patients were 50 years or older. Fifty-five (52%) patients received definitive RT, while 50 (48%) received postoperative RT after RP. The most used RT schemes were 36.5 Gray (Gy) in 5 fractions (fx) in 42 patients who underwent definitive prostate RT and 35 Gy in 5 fx in 27 patients who underwent postoperative RT. Thirty-eight of the patients (36.2%) received neoadjuvant or adjuvant ADT. Detailed baseline characteristics of the patients are given in Table 1. Table 2 displays the EPIC domain and subscales' internal consistency and test-retest correlation results. The Cronbach's alpha value of the whole scale was measured as 0.866, and it was revealed that the internal consistency of the Turkish EPIC scale was excellent. In addition, Cronbach's alpha values of the EPIC domains were measured between 0.654 and 0.969, and these results are within an acceptable range regarding internal consistency. Although Cronbach's alpha values were quite good for the reliability test, the value of the hormonal function subscale was measured relatively low (0.325). Test-retest correlations of the urinary, bowel, sexual, and hormonal domains were 0.805, 0.413, 0.861, and 0.639, respectively, which showed an acceptable correlation when the Turkish EPIC scale was repeated at 2-4 weeks intervals. Generally, the test-retest correlation values of the subscales resulted in at least moderate correlations. However, the bowel bother test-retest correlation value was measured as 0.247, representing a weak correlation. The median values of the EPIC domains and subscales and whether there is a statistical difference in the change over time between the values are given in Table 3. A statistically significant difference was found in the changes in all EPIC domain scores over time. This result revealed that the sensitivity to change method ensured the validity of the Turkish EPIC scale. No significant difference was found in the urinary incontinence and sexual bother subscales. The graphical distribution of the median values of the EPIC domain scores according to the measurement times is given in Fig. 1. Fig.1 Graphical distribution of the change of Turkish EPIC domains according to measurement times The interscale correlation analysis aimed to determine whether the scores obtained for different HRQoL domains complement each other. For this purpose, correlations between EPIC domain function and bother subscales were analyzed (see Table 4). We found that the function and bother subscales within each HRQoL domain were strongly correlated (r = 0.455 to 0.759), which means that the bother subscale measures the utility or impairment related to the domain's symptoms quantified by the corresponding function subscale. On the other hand, the correlations between the bother or function subscales among different HRQoL domains were consistently weaker (each r < 0.4), indicating that the urinary, sexual, bowel, and hormonal domains measure conceptually distinct HRQoL components. The correlation between HRQoL domain scores from EPIC and HRQoL scores of EORTC-QLQ C30 and PR 25 are given in Table 5 and Table 6, respectively. We found several correlations between the EPIC and EORTC QLQ-C30 scales. Specifically, there was a moderate correlation between the EPIC urinary domain and the EORTC QLQ-C30 GHS scale (r = 0.308). There was a moderate correlation between EORTC QLQ-C30 constipation and diarrhea scales with the EPIC bowel domain (r = -0.306 and -0.351, respectively). In the EPIC hormonal domain, there was a moderate correlation between the EORTC QLQ-C30 fatigue scale (r = -0.370). Additionally, there were strong correlations between the EPIC urinary domain and EORTC-QLQ PR25 urinary symptoms scale (r = -0.726), as well as between the EPIC sexual domain and EORTC-QLQ PR25 sexual activity scale (r = 0.769). Finally, there were moderate correlations between the EPIC urinary domain and EORTC-QLQ PR25 incontinence aid scale (r = -0.645), between the EPIC bowel domain and EORTC-QLQ PR25 bowel symptoms scale (r = -0.498), and between the EPIC sexual domain and both EORTC-QLQ PR25 hormone treatment-related symptoms (r = -0.495) and sexual functioning scales (r = 0.441). Exploratory factor analysis was conducted to determine the factor structure of the Turkish EPIC scale and compare it with the original English EPIC scale. The questions in the main and subscales were analyzed for their factor loads using component matrix analysis, and each clustered item was marked in a bold color (Supplementary File S2). Five factors were explained in factor analysis. Factor 1 showed a strong correlation with items related to the sexual domain, while Factor 2 was found to be correlated with items of the bowel domain. Factor 3 and 4 correlated with items of the urinary domain and Factor 5 correlated with items of the hormonal domain. DISCUSSION This study aimed to translate and validate the original EPIC questionnaire in Turkish. Two reliability and five validity analyses were successfully concluded, thus proving the validity and reliability of the Turkish EPIC scale. We initially planned to conduct our study with more patients, but due to the COVID-19 pandemic, our study was conducted with only 105 patients. There was a significant decrease in the number of patients applying to our department during the pandemic, and routine patient check-ups were postponed. Additionally, all surveys were performed face-to-face with patients in a private environment with a physician conducting the study, which may have contributed to the fewer participants. While there is a study in the literature validating the use of the EPIC-26 scale via the internet and telephone [20], we did not use this method as the patients' sociocultural characteristics differed from those in the relevant study. Additionally, we needed to determine whether the patients who participated in our study were proficient in using the internet or telephone to understand and answer the questions accurately. Despite these challenges, our study with 105 patients still provided an adequate number for scale validity and reliability analyses. SBRT has become increasingly popular in localized PCa due to its ability to complete treatment quickly, apply high fraction doses, and protect surrounding organs [21]. There are limited studies on HRQoL in treating PCa with SBRT. Some existing studies using EPIC scales in PCa patients who underwent SBRT showed that the treatment was well-tolerated and had an acceptable late side effect on HRQoL [22]. While a modest decrease in urinary and bowel HRQoL was observed during the first few months after SBRT, it rapidly returned to baseline levels in the following months. In our study, 66% of our patients received SBRT, which may contribute to expanding the use of the EPIC scale in PCa patients. Our study has another highlighted feature, including patients who underwent postoperative SBRT, a novel technique with limited analyses. A systematic review of 11 studies revealed that toxicity rates were acceptable and did not differ significantly from conventional schemes [23]. In a phase 2 study including patients who underwent postoperative SBRT, HRQoL was evaluated with the EPIC-26 scale [24]. Although moderate decreases were observed in bowel and urinary scale scores in the first month, the scores approached baseline values in the following months. The results of our study show a similar pattern to those mentioned in the literature. Although the general, main and subscale Cronbach's alpha values of our study were quite good for the reliability test, the Cronbach's alpha values of the hormonal functional subscale were relatively lower (0.325). The literature has not precisely defined a cut-off Cronbach alpha value indicating a weak or insignificant correlation. Generally, this value is directly proportional to the sample size, and Cronbach's alpha value generally increases as the sample size increases [25]. This result may have been caused by the number of patients participating in our study being lower than expected. However, this relatively low value did not adversely affect the reliability of the test. Several studies provide successful validations despite low Cronbach's alpha subscale values [7, 26]. When only Cronbach's alpha coefficient is considered in validation studies, the interpretation of results may need to be revised and may even lead to misinterpretation. It is essential to look at other factors as well. For this reason, in almost all studies where reliability analyses were performed, the reliability of the test was strengthened or confirmed by performing test-retest analysis in addition to Cronbach’s alpha coefficient analysis [25]. The test-retest coefficient values of the main scales of our study were measured in the range of 0.413-0.861, and this result shows that the Turkish EPIC scale is reproducible, at least to a moderate degree. However, the test-retest correlation value was measured as 0.247 in the bowel bother subscale, representing a weak correlation. One of the possible reasons for this result may be that the number of patients participating in our study was lower than expected. Another possible reason is that there has been a significant change in the patient's clinical condition or HRQoL between the two tests (2-4 weeks). RT was with SBRT technique in 66% of the patients in our study with high fraction doses which lasted in just over two weeks and the second test was applied to all patients on the last day of treatment or 1-2 weeks after treatment. In conventional fractionated RT however treatment lasted 6-8 weeks, and the second test usually was done in the middle of the treatment, when the likelihood of toxicity was relatively low. This situation was examined in a phase 3 randomized study, and GIS side effects at the end of treatment were observed more frequently in patients treated with SBRT than in patients treated with conventional RT [27]. Most of the GIS side effects measured in the study overlap with the symptom scales in the bowel bother subscale in our study. This situation, which can change rapidly in patients in a short time, may indicate that the test-retest period of 2-4 weeks in our study is inappropriate for the level of bowel bother. Another possible reason may be the high rate of antihemorrhoidal and antidiarrheal treatments administered to patients during treatment due to rapidly developing GI symptoms. Patients' symptomatic status may have changed due to these treatments, which may cause the retest to measure different results compared to the initial test. Nevertheless, the internal consistency of the bowel bother subscale was achieved (Cronbach's alpha coefficient: 0.684), and both the internal consistency and test-retest analysis of the bowel domain were reliable. The sensitivity to change validity method investigates whether the test applied at certain time intervals provides the expected change in those time intervals. In patients undergoing RT for PCa, a decrease/increase in HRQoL scores in EPIC is expected after RT, consistent with the side effects of RT. As a result of our study, changes in EPIC scores were observed over time compared to the baseline evaluation in all four main scales, and these changes were statistically significant when the five evaluations for each scale were analyzed together. In a phase 3 randomized study, HRQoL was measured in patients treated either by SBRT or conventional RT with the EPIC-26 scale [28]. Bowel HRQoL scores with the EPIC-26 scale was applied at baseline, 6th, 9th, 12th, and 24th months in that study and showed a moderate decrease between the 6th and 12th months similar to our findings in terms of general bowel HRQoL scale. In the same study, the pattern of the sexual HRQoL score between the 6th and 12th months was again similar to the sexual domain in our study. In an ideal HRQoL scale, correlation would be expected between subscales measuring similar HRQoL units. Additionally, weak or insignificant correlations are expected between subscales measuring different HRQoL units. In the interscale correlation analysis there was at least a moderate correlation between each related functional and bother subscales (r=0.455-0.759) in our study. This result shows that in the Turkish EPIC scale, the patient's functional status in each scale and the level of problems that the patient would create in their HRQoL due to the change in these functional statuses were questioned accurately and that the patients at the desired level could perceive the questions in the relevant scale. The same analysis achieved a weak or insignificant correlation between all independent subscales (r<0.250). This result shows that the Turkish EPIC scale can independently measure patients' four main symptom scales and that each scale is interpreted separately by the patients. Interscale analysis was also applied in the original EPIC study, and its results were similar to the results of our study [5]. EORTC-QLQ C30 is a general HRQoL scale that can be applied to many types of cancer. In our study only PCa patients were examined, so no significant correlation was expected between the Turkish EPIC scale and all subscales of the EORTC-QLQ C30 scale. On the contrary, EORTC-QLQ PR25 is a scale developed to measure HRQoL in PCa patients. Since it is a globally accepted scale, questions the same patient group, and has symptoms similar to the Turkish EPIC scale, correlation analyses were performed between this scale and the Turkish EPIC in our study. In general, at least a moderate correlation was found between equivalent scales. This result is similar to many studies in the literature [7-8, 29]. Factor analysis can investigate whether the original scale structure is preserved when the EPIC scale is translated into different languages or applied to populations in different cultures. Our analysis revealed that the main factor structure of the Turkish EPIC scale was divided into four domains and ten subscales, just like the original EPIC scale, and that the patients participating in our study could understand the differences between each subscale, just like the original scale. In the literature, factor analysis is rarely used in validation studies on HRQoL. In the French validation study of EPIC, factor analysis was applied, and the result was similar to ours [8]. In another study examining the psychometric analyses of EPIC scales, factor analysis of the EPIC-26 scale was conducted, and factor clustering was observed in most subscales [30]. CONCLUSIONS This study translated the EPIC scale into Turkish, and validity and reliability analyses were successfully performed. The Turkish EPIC scale has been shown to measure the HRQoL in PCa patients undergoing definitive and postoperative RT in the Turkish population. Declarations Author Contribution All authors contributed to the study conception and design. Material preparation and data collection were performed by Pervin Hurmuz, Gokhan Ozyigit and Burak Tilki. Data analysis was performed by Deniz Yuce. The first draft of the manuscript was written by Burak Tilki and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. STATEMENTS & DECLARATIONS The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. References Jemal A, Culp MB, Ma J, Islami F, Fedewa SA (2020) Prostate cancer incidence 5 years after US Preventive Services Task Force recommendations against screening. 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Journal of Consumer Research 21(2):381-391. https://doi:10.1086/209405 Marzorati C, Monzani D, Mazzocco K, Masiero M, Pavan F, Monturano M, Pravettoni G (2019) Validation of the Italian version of the abbreviated Expanded Prostate Cancer Index Composite (EPIC-26) in men with prostate cancer. Health Qual Life Outcomes 17(1):147. https://doi:10.1186/s12955-019-1214-x Fransson P, Nilsson P, Gunnlaugsson A, Beckman L, Tavelin B, Norman D et al (2021) Ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer (HYPO-RT-PC): patient-reported quality-of-life outcomes of a randomised, controlled, non-inferiority, phase 3 trial. Lancet Oncol 22(2):235-245. https://doi:10.1016/s1470-2045(20)30581-7 Tree AC, Ostler P, van der Voet H, Chu W, Loblaw A, Ford D et al (2022) Intensity-modulated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): 2-year toxicity results from an open-label, randomised, phase 3, non-inferiority trial. Lancet Oncol 23(10):1308-1320. https://doi:10.1016/s1470-2045(22)00517-4 Vigneault É, Savard J, Savard MH, Ivers H, Després P, Foster W, Martin A, Fradet V (2017) Validation of the French-Canadian version of the Expanded Prostate Cancer Index Composite (EPIC) in a French-Canadian population. Can Urol Assoc J 11(12):404-410. https://doi:10.5489/cuaj.4428 Axcrona K, Nilsson R, Brennhovd B, Sørebø Ø, Fosså SD, Dahl AA (2017) Psychometric properties of the Expanded Prostate Cancer Index Composite - 26 instrument in a cohort of radical prostatectomy patients: theoretical and practical examinations. BMC Urol 17(1):111. https://doi:10.1186/s12894-017-0302-7 Tables Tables 1-6 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Table1.docx Table2.docx Table3.docx Table4.docx Table5.docx Table6.docx SupplementaryFileS1.pdf SupplementaryFileS2.pdf 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4399475","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":305374739,"identity":"2814747e-7929-4857-aab7-9024a1aeb2b4","order_by":0,"name":"Burak Tilki","email":"","orcid":"","institution":"Hacettepe University","correspondingAuthor":false,"prefix":"","firstName":"Burak","middleName":"","lastName":"Tilki","suffix":""},{"id":305374740,"identity":"61a795d5-3239-457a-9380-5f1761fba3f0","order_by":1,"name":"Pervin 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18:55:17","extension":"pdf","order_by":7,"title":"","display":"","copyAsset":false,"role":"supplement","size":655534,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFileS1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4399475/v1/3f87a431a0c966a281d77694.pdf"},{"id":57874606,"identity":"0e792183-e393-4ca7-a600-3ed1c9284523","added_by":"auto","created_at":"2024-06-06 18:47:17","extension":"pdf","order_by":8,"title":"","display":"","copyAsset":false,"role":"supplement","size":417581,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFileS2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4399475/v1/5e9bee4e35360a1e03c02e26.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eThe Turkish Validation of the Expanded Prostate Cancer Index Composite (Epic) in Prostate Cancer Patients\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eProstate cancer (PCa) is the most common and the second lethal cancer among men worldwide\u0026nbsp;[1]. Approximately 19,450 new PCa cases were diagnosed in Turkey in 2020, and it is estimated that about 5,500 patients may die annually due to PCa\u0026nbsp;[2]. Depending on the stage of the disease, several treatment methods such as radical prostatectomy (RP), external beam radiotherapy (EBRT), brachytherapy (BRT), active surveillance, androgen deprivation therapy (ADT), and chemotherapy are used alone or in combination\u0026nbsp;[3]. Radiotherapy (RT) is one of the main treatment options for PCa and has a wide range of uses from the early to the metastatic stage. However, RT when alone or combined with other treatments has gastrointestinal system (GIS), genitourinary system (GUS), sexual and hormonal side effects and these complications may cause significant effects on patients\u0026rsquo; health-related quality of life (HRQoL). Especially in localized PCa, 10-year survival rates reach over 80%\u0026nbsp;[4]. In this patient group with a long life expectancy, the possible side effects of the treatments may come to the forefront in the patients\u0026rsquo; lives, which may affect their HRQoL. Many studies examine HRQoL in PCa patients, and many scales have been developed to measure HRQoL.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Expanded Prostate Index Composite (EPIC) was developed and validated in 2000 as a more comprehensive version of the University of California Los Angeles-Prostate Cancer Index (UCLA-PCI) questionnaire\u0026nbsp;[5, 6]. In this scale, patients\u0026apos; complaints about RP, ERT, BRT, and ADT were evaluated in the light of the literature. The original English scale comprised 50 questions encompassing four main domains: urinary, bowel, sexual and hormonal.\u003c/p\u003e\n\u003cp\u003eThe EPIC has been translated and validated in several other languages (i.e., German, French, Korean, Brazilian, Japanese) [7-12]. In addition, two abbreviated versions of the EPIC have been created and validated (EPIC-26 and EPIC-CP) [13, 14]. To our knowledge, there is no Turkish translation and ours is the first study to translate and validate the Turkish version of EPIC. In this context, this study aimed to translate and validate the Turkish version of the original EPIC questionnaire.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e\u003cstrong\u003eStudy Population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients previously diagnosed with biopsy-proven PCa and received RT at our department between 01.06.2019 and 01.12.2021 were accrued in this study. Patients\u0026nbsp;with biopsy-proven PCa aged \u0026ge; 18 years, diagnosed with T1-4N0M0 tumor according to American Joint Commission on Cancer (AJCC) 8th edition, receiving adjuvant or salvage RT after RP or being treated with definitive RT, with Karnofsky Performance Score (KPS) \u0026ge; 70 were included in this study. Patients with distant metastasis, lymph node involvement, previous pelvic RT, transurethral resection and cancer history were excluded. Informed consent was obtained from all patients at the beginning of the study. Approval for the study was obtained from Hacettepe University Non-Interventional Clinical Research Ethics Committee on April 2, 2019, with registration number GO 19/331 and conducted by the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy Procedure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patients were evaluated using the Turkish EPIC, EORTC-QLQ C30, and EORTC-QLQ PR25 questionnaires at different time intervals. Patients were asked to fulfill the questionnaires before RT (baseline-T\u003csub\u003e1\u003c/sub\u003e), 2-4 weeks after the initiation of RT (second assessment-T\u003csub\u003e2\u003c/sub\u003e), three (T\u003csub\u003e3\u003c/sub\u003e), six (T\u003csub\u003e4\u003c/sub\u003e), and twelve (T\u003csub\u003e5\u003c/sub\u003e) months follow-up visits. Patients were given both face-to-face and solitary applications, and their responses were documented on questionnaire forms and stored in a database. The data of the patients who completed the baseline and second assessment questionnaires were examined for reliability and validity analyses. The patients data who completed all the questionnaires were analyzed for sensitivity to change analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ) C30 contains 30 items and assesses eight symptom scales as fatigue, nausea and vomiting, pain, dyspnea, insomnia, appetite loss, constipation, and diarrhea, five functional scales as physical, role, emotional, cognitive, and social functioning, global health status (GHS), and financial difficulties\u0026nbsp;[15]. For each scale, a separate score is produced. Scores vary from 0 (worst) to 100 (best) for the functional scales and GHS and from 0 (best) to 100 (worst) for the symptom scales and were generated according to the EORTC Scoring Manual.\u003c/p\u003e\n\u003cp\u003eThe 25 items in the EORTC-QLQ PR25 module measure two functional scales (sexual activity and sexual functioning) and four symptomatic scales (urinary symptoms, bowel symptoms, hormone treatment-related symptoms, and incontinence aid) that are all unique to PCa\u0026nbsp;[16]. This module was required along with completing the QLQ-C30 questionnaire. Like the QLQ-C30, a single score is created for each measure and standardized on a 0-100 scale, where a high score denotes a high symptomatology or functional impairment level.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTranslation and Cultural Adaptation of the Turkish Version of EPIC\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTranslation and cultural adaptation of the Turkish Version of EPIC were performed according to ISPOR Task Force Group recommendations\u0026nbsp;[17]. Two proficient translators independently translated the original English EPIC questionnaire from English to Turkish followed by a separate evaluation by another researcher with an exceptional level of English, and the first Turkish form of the questionnaire was created. Another professional translator translated the completed survey from Turkish to English. All researchers participating in the study made final corrections in the translation, considering the linguistic and cultural differences between the original form and the Turkish translation. Afterward, a pilot study was conducted in 20 patients. In the pilot study, patients were asked which questions they had difficulty in understanding after the face-to-face survey study. When the patients received no negative feedback, the final version of the Turkish form was considered complete (Supplementary File\u0026nbsp;S\u003ca href=\"https://link.springer.com/article/10.1007/s11136-024-03648-6#MOESM1\"\u003e1)\u003c/a\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analyses\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor continuous variables, mean \u0026plusmn; standard deviation (SD) or median (interquartile range-IQR) and number (%) are used to characterize the patients\u0026apos; baseline sociodemographic and clinical features.\u003c/p\u003e\n\u003cp\u003eTwo measures were used to assess the reliability of the instruments; internal consistency and test-retest reliability. The Cronbach\u0026apos;s alpha test was used to evaluate the scale\u0026apos;s internal consistency, which produces a coefficient between 0 and 1. An acceptable coefficient range for reliability analysis is between 0.70-0.95\u0026nbsp;[18]. The test-retest reliability method measures the consistency of responses to repeated measures of the same questionnaires. To minimize the effect of possible confounding variables, such as recovery and learning effects, a two-week interval was considered as the optimal time duration for the retest\u0026nbsp;[19]. The intraclass correlation coefficient (ICC) was used to evaluate test-retest reliability, and interscale correlations and correlations between EPIC, EORTC-QLQ C30, and EORTC-QLQ PR25 were assessed using Spearman correlation coefficients (r), which indicates the strength of the relationship between two variables. Relationships between 0.00 and 0.10 were considered negligible, while relationships between 0.10 and 0.30 were considered weak correlations. Relationships between 0.30-0.69 were considered moderate, 0.70-0.89 were considered strong, and 0.90-1.00 were considered very strong correlations. The type 1 error was used at 5% for statistical significance.\u003c/p\u003e\n\u003cp\u003eFace validity, in which the pilot study was conducted with 20 patients, was evaluated and first assessed to investigate the study\u0026apos;s validity. Subsequently, the change in HRQoL scores of the questionnaires administered at five different times was analyzed using the sensitivity to change method. The relationship between subscales was evaluated with interscale correlation analysis. Criterion validity analysis was performed by comparing the results of the EORTC-QLQ C30 and PR25 scales with the results of the Turkish EPIC scale. Finally, exploratory factor analyses were performed for the scale\u0026apos;s factor structure during the validation process. The desired factor load value in factor analysis is values greater than 0.30. The study was analyzed with SPSS v.23 (IBM Corp., Armonk, NY, USA) software.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 105 patients were included in the study. Around 97% of the patients were 50 years or older. Fifty-five (52%) patients received definitive RT, while 50 (48%) received postoperative RT after RP. The most used RT schemes were 36.5 Gray (Gy) in 5 fractions (fx) in 42 patients who underwent definitive prostate RT and 35 Gy in 5 fx in 27 patients who underwent postoperative RT. Thirty-eight of the patients (36.2%) received neoadjuvant or adjuvant ADT. Detailed baseline characteristics of the patients are given in Table 1.\u003c/p\u003e\n\u003cp\u003eTable 2 displays the EPIC domain and subscales\u0026apos; internal consistency and test-retest correlation results. The Cronbach\u0026apos;s alpha value of the whole scale was measured as 0.866, and it was revealed that the internal consistency of the Turkish EPIC scale was excellent. In addition, Cronbach\u0026apos;s alpha values of the EPIC domains were measured between 0.654 and 0.969, and these results are within an acceptable range regarding internal consistency. Although Cronbach\u0026apos;s alpha values were quite good for the reliability test, the value of the hormonal function subscale was measured relatively low (0.325). Test-retest correlations of the urinary, bowel, sexual, and hormonal domains were 0.805, 0.413, 0.861, and 0.639, respectively, which showed an acceptable correlation when the Turkish EPIC scale was repeated at 2-4 weeks intervals. Generally, the test-retest correlation values of the subscales resulted in at least moderate correlations. However, the bowel bother test-retest correlation value was measured as 0.247, representing a weak correlation.\u003c/p\u003e\n\u003cp\u003eThe median values of the EPIC domains and subscales and whether there is a statistical difference in the change over time between the values are given in Table 3. A statistically significant difference was found in the changes in all EPIC domain scores over time. This result revealed that the sensitivity to change method ensured the validity of the Turkish EPIC scale. No significant difference was found in the urinary incontinence and sexual bother subscales. The graphical distribution of the median values of the EPIC domain scores according to the measurement times is given in Fig. 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFig.1\u003c/strong\u003e Graphical distribution of the change of Turkish EPIC domains according to measurement times\u003c/p\u003e\n\u003cp\u003eThe interscale correlation analysis aimed to determine whether the scores obtained for different HRQoL domains complement each other. For this purpose, correlations between EPIC domain function and bother subscales were analyzed (see Table 4). We found that the function and bother subscales within each HRQoL domain were strongly correlated (r = 0.455 to 0.759), which means that the bother subscale measures the utility or impairment related to the domain\u0026apos;s symptoms quantified by the corresponding function subscale. On the other hand, the correlations between the bother or function subscales among different HRQoL domains were consistently weaker (each r \u0026lt; 0.4), indicating that the urinary, sexual, bowel, and hormonal domains measure conceptually distinct HRQoL components.\u003c/p\u003e\n\u003cp\u003eThe correlation between HRQoL domain scores from EPIC and HRQoL scores of EORTC-QLQ C30 and PR 25 are given in Table 5 and Table 6, respectively. We found several correlations between the EPIC and EORTC QLQ-C30 scales. Specifically, there was a moderate correlation between the EPIC urinary domain and the EORTC QLQ-C30 GHS scale (r = 0.308). There was a moderate correlation between EORTC QLQ-C30 constipation and diarrhea scales with the EPIC bowel domain (r = -0.306 and -0.351, respectively). In the EPIC hormonal domain, there was a moderate correlation between the EORTC QLQ-C30 fatigue scale (r = -0.370). Additionally, there were strong correlations between the EPIC urinary domain and EORTC-QLQ PR25 urinary symptoms scale (r = -0.726), as well as between the EPIC sexual domain and EORTC-QLQ PR25 sexual activity scale (r = 0.769). Finally, there were moderate correlations between the EPIC urinary domain and EORTC-QLQ PR25 incontinence aid scale (r = -0.645), between the EPIC bowel domain and EORTC-QLQ PR25 bowel symptoms scale (r = -0.498), and between the EPIC sexual domain and both EORTC-QLQ PR25 hormone treatment-related symptoms (r = -0.495) and sexual functioning scales (r = 0.441).\u003c/p\u003e\n\u003cp\u003eExploratory factor analysis was conducted to determine the factor structure of the Turkish EPIC scale and compare it with the original English EPIC scale. The questions in the main and subscales were analyzed for their factor loads using component matrix analysis, and each clustered item was marked in a bold color (Supplementary File S2). Five factors were explained in factor analysis. Factor 1 showed a strong correlation with items related to the sexual domain, while Factor 2 was found to be correlated with items of the bowel domain. Factor 3 and 4 correlated with items of the urinary domain and Factor 5 correlated with items of the hormonal domain.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study aimed to translate and validate the original EPIC questionnaire in Turkish. Two reliability and five validity analyses were successfully concluded, thus proving the validity and reliability of the Turkish EPIC scale.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;We initially planned to conduct our study with more patients, but due to the COVID-19 pandemic, our study was conducted with only 105 patients. There was a significant decrease in the number of patients applying to our department during the pandemic, and routine patient check-ups were postponed. Additionally, all surveys were performed face-to-face with patients in a private environment with a physician conducting the study, which may have contributed to the fewer participants. While there is a study in the literature validating the use of the EPIC-26 scale via the internet and telephone\u0026nbsp;[20], we did not use this method as the patients\u0026apos; sociocultural characteristics differed from those in the relevant study. Additionally, we needed to determine whether the patients who participated in our study were proficient in using the internet or telephone to understand and answer the questions accurately. Despite these challenges, our study with 105 patients still provided an adequate number for scale validity and reliability analyses.\u003c/p\u003e\n\u003cp\u003eSBRT has become increasingly popular in localized PCa due to its ability to complete treatment quickly, apply high fraction doses, and protect surrounding organs\u0026nbsp;[21]. There are limited studies on HRQoL in treating PCa with SBRT. Some existing studies using EPIC scales in PCa patients who underwent SBRT showed that the treatment was well-tolerated and had an acceptable late side effect on HRQoL\u0026nbsp;[22]. While a modest decrease in urinary and bowel HRQoL was observed during the first few months after SBRT, it rapidly returned to baseline levels in the following months. In our study, 66% of our patients received SBRT, which may contribute to expanding the use of the EPIC scale in PCa patients.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur study has another highlighted feature, including patients who underwent postoperative SBRT, a novel technique with limited analyses. A systematic review of 11 studies revealed that toxicity rates were acceptable and did not differ significantly from conventional schemes\u0026nbsp;[23]. In a phase 2 study including patients who underwent postoperative SBRT, HRQoL was evaluated with the EPIC-26 scale\u0026nbsp;[24]. Although moderate decreases were observed in bowel and urinary scale scores in the first month, the scores approached baseline values in the following months. The results of our study show a similar pattern to those mentioned in the literature.\u003c/p\u003e\n\u003cp\u003eAlthough the general, main and subscale Cronbach\u0026apos;s alpha values of our study were quite good for the reliability test, the Cronbach\u0026apos;s alpha values of the hormonal functional subscale were relatively lower (0.325). The literature has not precisely defined a cut-off Cronbach alpha value indicating a weak or insignificant correlation. Generally, this value is directly proportional to the sample size, and Cronbach\u0026apos;s alpha value generally increases as the sample size increases\u0026nbsp;[25]. This result may have been caused by the number of patients participating in our study being lower than expected. However, this relatively low value did not adversely affect the reliability of the test. Several studies provide successful validations despite low Cronbach\u0026apos;s alpha subscale values\u0026nbsp;[7,\u0026nbsp;26]. When only Cronbach\u0026apos;s alpha coefficient is considered in validation studies, the interpretation of results may need to be revised and may even lead to misinterpretation. It is essential to look at other factors as well. For this reason, in almost all studies where reliability analyses were performed, the reliability of the test was strengthened or confirmed by performing test-retest analysis in addition to Cronbach\u0026rsquo;s alpha coefficient analysis\u0026nbsp;[25].\u003c/p\u003e\n\u003cp\u003eThe test-retest coefficient values of the main scales of our study were measured in the range of 0.413-0.861, and this result shows that the Turkish EPIC scale is reproducible, at least to a moderate degree. However, the test-retest correlation value was measured as 0.247 in the bowel bother subscale, representing a weak correlation. One of the possible reasons for this result may be that the number of patients participating in our study was lower than expected. Another possible reason is that there has been a significant change in the patient\u0026apos;s clinical condition or HRQoL between the two tests (2-4 weeks). RT was with SBRT technique in 66% of the patients in our study with high fraction doses which lasted in just over two weeks and the second test was applied to all patients on the last day of treatment or 1-2 weeks after treatment. In conventional fractionated RT however treatment lasted 6-8 weeks, and the second test usually was done in the middle of the treatment, when the likelihood of toxicity was relatively low. This situation was examined in a phase 3 randomized study, and GIS side effects at the end of treatment were observed more frequently in patients treated with SBRT than in patients treated with conventional RT\u0026nbsp;[27]. Most of the GIS side effects measured in the study overlap with the symptom scales in the bowel bother subscale in our study. This situation, which can change rapidly in patients in a short time, may indicate that the test-retest period of 2-4 weeks in our study is inappropriate for the level of bowel bother. Another possible reason may be the high rate of antihemorrhoidal and antidiarrheal treatments administered to patients during treatment due to rapidly developing GI symptoms. Patients\u0026apos; symptomatic status may have changed due to these treatments, which may cause the retest to measure different results compared to the initial test. Nevertheless, the internal consistency of the bowel bother subscale was achieved (Cronbach\u0026apos;s alpha coefficient: 0.684), and both the internal consistency and test-retest analysis of the bowel domain were reliable.\u003c/p\u003e\n\u003cp\u003eThe sensitivity to change validity method investigates whether the test applied at certain time intervals provides the expected change in those time intervals. In patients undergoing RT for PCa, a decrease/increase in HRQoL scores in EPIC is expected after RT, consistent with the side effects of RT. As a result of our study, changes in EPIC scores were observed over time compared to the baseline evaluation in all four main scales, and these changes were statistically significant when the five evaluations for each scale were analyzed together. In a phase 3 randomized study, HRQoL was measured in patients treated either by SBRT or conventional RT with the EPIC-26 scale\u0026nbsp;[28]. Bowel HRQoL scores with the EPIC-26 scale was applied at baseline, 6th, 9th, 12th, and 24th months in that study and showed a moderate decrease between the 6th and 12th months similar to our findings in terms of general bowel HRQoL scale. In the same study, the pattern of the sexual HRQoL score between the 6th and 12th months was again similar to the sexual domain in our study.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;In an ideal HRQoL scale, correlation would be expected between subscales measuring similar HRQoL units. Additionally, weak or insignificant correlations are expected between subscales measuring different HRQoL units. In the interscale correlation analysis there was at least a moderate correlation between each related functional and bother subscales (r=0.455-0.759) in our study. This result shows that in the Turkish EPIC scale, the patient\u0026apos;s functional status in each scale and the level of problems that the patient would create in their HRQoL due to the change in these functional statuses were questioned accurately and that the patients at the desired level could perceive the questions in the relevant scale. The same analysis achieved a weak or insignificant correlation between all independent subscales (r\u0026lt;0.250). This result shows that the Turkish EPIC scale can independently measure patients\u0026apos; four main symptom scales and that each scale is interpreted separately by the patients. Interscale analysis was also applied in the original EPIC study, and its results were similar to the results of our study\u0026nbsp;[5].\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;EORTC-QLQ C30 is a general HRQoL scale that can be applied to many types of cancer. In our study only PCa patients were examined, so no significant correlation was expected between the Turkish EPIC scale and all subscales of the EORTC-QLQ C30 scale. On the contrary, EORTC-QLQ PR25 is a scale developed to measure HRQoL in PCa patients. Since it is a globally accepted scale, questions the same patient group, and has symptoms similar to the Turkish EPIC scale, correlation analyses were performed between this scale and the Turkish EPIC in our study. In general, at least a moderate correlation was found between equivalent scales. This result is similar to many studies in the literature\u0026nbsp;[7-8, 29].\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Factor analysis can investigate whether the original scale structure is preserved when the EPIC scale is translated into different languages or applied to populations in different cultures. Our analysis revealed that the main factor structure of the Turkish EPIC scale was divided into four domains and ten subscales, just like the original EPIC scale, and that the patients participating in our study could understand the differences between each subscale, just like the original scale. In the literature, factor analysis is rarely used in validation studies on HRQoL. In the French validation study of EPIC, factor analysis was applied, and the result was similar to ours\u0026nbsp;[8]. In another study examining the psychometric analyses of EPIC scales, factor analysis of the EPIC-26 scale was conducted, and factor clustering was observed in most subscales\u0026nbsp;[30].\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eThis study translated the EPIC scale into Turkish, and validity and reliability analyses were successfully performed. The Turkish EPIC scale has been shown to measure the HRQoL in PCa patients undergoing definitive and postoperative RT in the Turkish population.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation and data collection were performed by Pervin Hurmuz, Gokhan Ozyigit and Burak Tilki. Data analysis was performed by Deniz Yuce. The first draft of the manuscript was written by Burak Tilki and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSTATEMENTS \u0026amp; DECLARATIONS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eJemal A, Culp MB, Ma J, Islami F, Fedewa SA (2020) Prostate cancer incidence 5 years after US Preventive Services Task Force recommendations against screening. J Natl Cancer Inst 113(1):64-71. https://doi:10.1093/jnci/djaa068\u003c/li\u003e\n \u003cli\u003eSung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, Bray F (2021) Global Cancer Statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 71(3):209-249. https://doi:10.3322/caac.21660\u003c/li\u003e\n \u003cli\u003eNetwork, N.C.C.N. Prostate Cancer (Version 1.2023). 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Urology 76(5):1245-1250. https://doi:10.1016/j.urology.2010.01.027\u003c/li\u003e\n \u003cli\u003eChang P, Szymanski KM, Dunn RL, Chipman JJ, Litwin MS, Nguyen PL et al (2011) Expanded Prostate Cancer İndex Composite for clinical practice: development and validation of a practical health related quality of life instrument for use in the routine clinical care of patients with prostate cancer. J Urol 186(3):865-872. https://doi:10.1016/j.juro.2011.04.085\u003c/li\u003e\n \u003cli\u003eAaronson NK, Ahmedzai S, Bergman B, Bullinger M, Cull A, Duez NJ et al (1993) The European Organization for Research and Treatment of Cancer QLQ-C30: a quality-of-life instrument for use in international clinical trials in oncology. 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Psychometrika 16(3):297-334. https://doi:10.1007/BF02310555\u003c/li\u003e\n \u003cli\u003eDeyo RA, Diehr P, Patrick DL (1991) Reproducibility and responsiveness of health status measures. Statistics and strategies for evaluation. Controlled Clin Trials 12:142-158. https://doi:10.1016/s0197-2456(05)80019-4\u003c/li\u003e\n \u003cli\u003eEinstein DJ, Patil D, Chipman J, Regan MM, Davis K, Crociani CM et al (2019) Expanded Prostate Cancer Index Composite-26 (EPIC-26) online: validation of an internet-based instrument for assessment of health-related quality of life after treatment for localized prostate cancer. Urology 127:53-60. https://doi:10.1016/j.urology.2019.02.004\u003c/li\u003e\n \u003cli\u003eStokes WA, Kavanagh BD, Raben D, Pugh TJ (2017) Implementation of hypofractionated prostate radiation therapy in the United States: A National Cancer Database analysis. Pract Radiat Oncol 7(4):270-278. https://doi:10.1016/j.prro.2017.03.011\u003c/li\u003e\n \u003cli\u003eKing CR, Collins S, Fuller D, Wang PC, Kupelian P, Steinberg M, Katz A (2013) Health-related quality of life after stereotactic body radiation therapy for localized prostate cancer: results from a multi-institutional consortium of prospective trials. Int J Radiat Oncol Biol Phys 87(5):939-945. https://doi:10.1016/j.ijrobp.2013.08.019\u003c/li\u003e\n \u003cli\u003eSchr\u0026ouml;der C, Tang H, Windisch P, Zwahlen DR, Buchali A, Vu E et al (2022) Stereotactic radiotherapy after radical prostatectomy in patients with prostate cancer in the adjuvant or salvage setting: a systematic review. Cancers (Basel) 14(3). https://doi:10.3390/cancers14030696\u003c/li\u003e\n \u003cli\u003eMa TM, Ballas LK, Wilhalme H, Sachdeva A, Chong N, Sharma S et al (2023) Quality-of-life outcomes and toxicity profile among patients with localized prostate cancer after radical prostatectomy treated with stereotactic body radiation: the SCIMITAR multicenter phase 2 trial. Int J Radiat Oncol Biol Phys 115(1):142-152. https://doi:10.1016/j.ijrobp.2022.08.041\u003c/li\u003e\n \u003cli\u003ePeterson RA (1994) A meta-analysis of Cronbach\u0026apos;s coefficient alpha. Journal of Consumer Research 21(2):381-391. https://doi:10.1086/209405\u003c/li\u003e\n \u003cli\u003eMarzorati C, Monzani D, Mazzocco K, Masiero M, Pavan F, Monturano M, Pravettoni G (2019) Validation of the Italian version of the abbreviated Expanded Prostate Cancer Index Composite (EPIC-26) in men with prostate cancer. Health Qual Life Outcomes 17(1):147. https://doi:10.1186/s12955-019-1214-x\u003c/li\u003e\n \u003cli\u003eFransson P, Nilsson P, Gunnlaugsson A, Beckman L, Tavelin B, Norman D et al (2021) Ultra-hypofractionated versus conventionally fractionated radiotherapy for prostate cancer (HYPO-RT-PC): patient-reported quality-of-life outcomes of a randomised, controlled, non-inferiority, phase 3 trial. Lancet Oncol 22(2):235-245. https://doi:10.1016/s1470-2045(20)30581-7\u003c/li\u003e\n \u003cli\u003eTree AC, Ostler P, van der Voet H, Chu W, Loblaw A, Ford D et al (2022) Intensity-modulated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): 2-year toxicity results from an open-label, randomised, phase 3, non-inferiority trial. Lancet Oncol 23(10):1308-1320. https://doi:10.1016/s1470-2045(22)00517-4\u003c/li\u003e\n \u003cli\u003eVigneault \u0026Eacute;, Savard J, Savard MH, Ivers H, Despr\u0026eacute;s P, Foster W, Martin A, Fradet V (2017) Validation of the French-Canadian version of the Expanded Prostate Cancer Index Composite (EPIC) in a French-Canadian population. Can Urol Assoc J 11(12):404-410. https://doi:10.5489/cuaj.4428\u003c/li\u003e\n \u003cli\u003eAxcrona K, Nilsson R, Brennhovd B, S\u0026oslash;reb\u0026oslash; \u0026Oslash;, Foss\u0026aring; SD, Dahl AA (2017) Psychometric properties of the Expanded Prostate Cancer Index Composite - 26 instrument in a cohort of radical prostatectomy patients: theoretical and practical examinations. BMC Urol 17(1):111. https://doi:10.1186/s12894-017-0302-7\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1-6 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Quality of Life, Prostate Cancer, Radiotherapy, Validation Study, Stereotactic Body Radiotherapy","lastPublishedDoi":"10.21203/rs.3.rs-4399475/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4399475/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose:\u003c/strong\u003e The Expanded Prostate Cancer Index Composite (EPIC) is a symptom scale that measures health-related quality of life (HRQoL) in prostate cancer (PCa) patients. This scale is translated into different languages and used in daily practice. This study aimed to translate the EPIC scale into Turkish and provide Turkish validation by conducting validity and reliability analyses.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Patients with biopsy-proven PCa who received definitive or postoperative radiotherapy (RT) at our department were included. All participants were evaluated using the Turkish EPIC, The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ) C30, and EORTC-QLQ PR25 questionnaires at five different time intervals. First, the original English version of the EPIC was translated into Turkish, and then, two reliability and five validity analyses were performed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e One hundred-five patients were included in the study. In the reliability analyses, Cronbach's alpha values of the whole scale were measured at 0.866, and the main scales' Cronbach's alpha values were measured between 0.654 and 0.969. In the test-retest analysis, the correlation values of the main scales were measured between 0.413 and 0.861. The pilot study with 20 patients was completed, thus providing face validity. Sensitivity to change analysis, interscale correlation, criterion validity, and explanatory factor analyses were performed, and results proving the scale's validity were obtained in all analyses.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e The Turkish EPIC scale is applicable for patients in the Turkish population diagnosed with PCa who received either definitive or postoperative RT.\u003c/p\u003e","manuscriptTitle":"The Turkish Validation of the Expanded Prostate Cancer Index Composite (Epic) in Prostate Cancer Patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-06 18:47:12","doi":"10.21203/rs.3.rs-4399475/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":"4ce8c884-cf27-4fbf-893f-4a96840e1e1e","owner":[],"postedDate":"June 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-06-17T16:09:49+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-06 18:47:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4399475","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4399475","identity":"rs-4399475","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}