Methodology of a population-based survey of headache disorders among adults in Latvia

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This paper details the adaptation and modification of the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire for the Latvian population, the methodology of its application and the challenges encountered. Methods We adapted the HARDSHIP questionnaire to local requirements and translated it into Latvian, the official state language, and Russian, the most widely spoken minority language. We used a population-based cross-sectional quota and stratified sampling method. Stratification variables were gender, age, nationality, type of settlement, region and highest level of education completed. Potential participants were engaged through computer-assisted random-digit dialling, followed by a telephone interview of those willing. A pilot study was conducted to assess feasibility. The main study was conducted from October 2023 to January 2024. Results Translation challenges were few and successfully addressed. The pilot survey verified the questionnaire’s applicability. We contacted 21,436 individuals, of whom 16,371 were potential participants and 2,141 accepted the invitation and completed the interview (participation proportion: 13.1%). The gender (48.2% males, p = 0.12), age (mean, 43.3 years, p = 0.81), region (p = 0.88), habitation (p = 0.44), and nationality (p = 0.41) distributions of the sample were statistically similar to those of the national population aged 18–65. People of higher education (40.6% vs. 36.1%, p < 0.001) were overrepresented. Conclusions This is the first population-based survey of headache disorders in Latvia, following the recommendations on population surveys of headache disorders from the Global Campaign against Headache. The HARDSHIP questionnaire was successfully translated and adapted to local requirements. Despite a low participation proportion, the sample was highly representative of the general population regarding age, gender and habitation. Trial registration No clinical trials performed in the study. headache epidemiology methodology population-based survey cross-sectional Latvia global campaign against headache Figures Figure 1 Contributions to the literature This is the first population-based study on headache disorders conducted in Latvia. It fills a geographical gap in the Global Campaign against Headache, contributing new data from an underrepresented European region. The study provides a tested and culturally adapted version of the HARDSHIP questionnaire in both Latvian and Russian. It demonstrates the feasibility of using computer-assisted telephone interviews for headache epidemiology in multilingual populations. The findings support future public health planning and policy development for headache care in Latvia and similar settings. Background In 2014, the Global Campaign against Headache [ 1 , 2 ], led by the UK-based non-governmental organisation Lifting The Burden (LTB), published guidelines for conducting and reporting population-based studies on headache disorders [ 3 ]. Along with these, and recommended in the guidelines, was the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire [ 4 ]. HARDSHIP is an instrument for assessing prevalence and attributable burden of the headache disorders of public health importance. It has been used in diverse populations in various geographical regions, with adaptations to ensure cultural and contextual relevance while preserving its reliability and validity [ 5 – 15 ]. Although used in Russia [ 9 ] and Lithuania [ 15 ], these methods have not been applied to Latvia's population. Neither have other studies examined the prevalence and burden of headache disorders in the general population of this country. We report here the adaptation of the HARDSHIP questionnaire to a Latvian setting, including translation into Latvian, the official state language, and Russian, the most widely spoken minority language. The survey method is described in detail, along with the challenges encountered during the study. We also present a detailed account of the essential characteristics of the sample, and comment on its validity as a representative sample of the population of interest. Methods Study design This was a population-based cross-sectional survey that utilised a structured questionnaire in telephone interviews, engaging participants through computer-assisted random-digit dialling. A pilot study was conducted to assess its feasibility. Questionnaire adaptation and translation We adapted the HARDSHIP questionnaire for use in Latvia, selecting questions for inclusion according to its modular design [ 4 ]. This adapted version was translated into Latvian, the official state language, and into Russian, since Russian speakers constitute the most prevalent minority (37.7% of the Latvian population [ 16 ]). To ensure linguistic and cultural appropriateness, we followed the translation protocol for hybrid documents developed by the Global Campaign [ 17 ]. Two native speakers of Latvian or Russian, bilingual in English, one a headache expert, DJ (Latvian) or AK (Russian), and the other a professional translator, MN (Latvian) or LZ (Russian), independently performed the translations. Any discrepancies were resolved through discussion between the headache experts, the translators and the study coordinator (LM), creating a forward translation agreed by consensus. Literal back-translations of these, from each language into English, were performed by professional translators (BK [Latvian] or DS [Russian]). Each of these was reviewed and compared item by item against the original questionnaire by its principal author (TJS). When conceptual equivalence appeared to have been lost in translation or meaning distorted, the forward translations were amended accordingly. Pilot study The pilot study was conducted among a convenience sample of 30 patients (15 Latvian speakers and 15 Russian speakers) immediately following their initial consultations and diagnosis of migraine, tension-type headache (TTH) or medication-overuse headache (MOH) according to the criteria of the International Classification of Headache Disorders third edition (ICHD-3) [ 18 ]. Face-to-face interviews assessed the comprehensibility and acceptability of the questionnaire and the duration of interviews. Questions or response options that were not immediately understood were repeated slowly, with requests to choose the most appropriate option for the latter. Participants were actively encouraged to voice their concerns about the questionnaire. Amendments were made in response to these and any other difficulties that became apparent. Participants in the pilot study were not included in the main study. Main study Data were collected from October 30th 2023 to January 24th 2024. Sampling We employed a population-based, cross-sectional design using a stratified quota sampling method to ensure representativeness of the Latvian population. To facilitate random selection, we implemented a random-digit dialling approach, incorporating the national country code (+ 371) [ 19 ]. This method enabled the generation of seven- and eight-digit numbers across all relevant landline and mobile prefixes, in accordance with the Latvian telephone numbering plan. Dialling continued iteratively until the target sample size was reached, thereby supporting the reliability and generalisability of our findings. Following established methodological guidelines [ 3 ], we aimed for a sample size of 2,100 respondents, which was considered sufficient to balance statistical power with the constraints of available resources. This target was proportionally distributed according to national population data [ 20 , 21 ], with the aim of ensuring appropriate demographic representation. To achieve this, we applied hard-limit stratification criteria for key demographic domains: gender, age, geographic region, settlement type (urban or rural), and primary language (Latvian or Russian), in accordance with national census data [ 20 , 21 ]. Education level served as a soft-limit stratification variable, acting more as a guideline for recruitment rather than a strict requirement. To avoid increasing the study's costs, we were satisfied with reaching 94% of the education quota limit. Engagement with participants, and data collection When a phone call was successfully connected, the interviewer explained that participation was voluntary and confidential, and asked for consent to proceed with the interview. Only then were the inclusion criteria applied (aged 18–65 years; resident in Latvia for at least the preceding 12 months; cognitively able to understand and respond to the study questions, and able to communicate effectively in Latvian or Russian). When these were fulfilled, the stratification questions were asked, and the interview continued. Interviews were conducted by 24 professional interviewers with experience in statistical market research data collection and medical research, although without specific expertise in headache disorders. All participants underwent training that covered the study objectives, research methodology, interview protocols and an overview of typical primary and secondary headaches. Continuous support and guidance were available from the principal investigator throughout the data collection period. The interviews were programmed using the NIPO Computer-Assisted Telephone Interviewing (CATI)/Web Fieldwork system. Real-time data entry by the interviewers obviated transcription errors, while built-in measures, ensuring adherence to established formats, promoted complete and accurate data entry. Targeted data entry restrictions and automatic range validation ensured user inputs aligned with question structure, relevant periods and feasible ranges. The system issued immediate feedback to interviewers and provided prompts for correction when entries breached these. Conditional logic made specific fields mandatory in accordance with prior responses. Headache diagnoses Headache diagnoses were determined using the HARDSHIP diagnostic algorithm applying modified ICHD-3 criteria [ 3 ]. Only participants reporting headache in the past year were diagnosed. Those who reported ≥ 15 headache days/month (H15+) were classified as probable MOH (pMOH) when also reporting medication use on ≥ 10 days/month and otherwise as other H15+. Those with < 15 headache days/month were hierarchically classified according to reported symptoms (of their most bothersome headache type when multiple types were present) as definite migraine, definite TTH, probable migraine or probable TTH. Participants not fulfilling any of these diagnostic criteria were classified as having unclassified headache. The enquiry also included headache on the day preceding the interview (headache yesterday [HY]). This was not diagnosed because ICHD-3 criteria apply to disorders, not single episodes. Analysis Using chi-squared tests, we compared the study sample with the general adult population of Latvia according to gender, nationality, age, region, type of residence and education. Statistical analyses were performed using RStudio version 2024.04.0 + 735. Results Adaptation, translation and pilot study Adaptations were minimal: almost all questions from the original HARDSHIP questionnaire [ 3 ] were deemed appropriate and included (Supplementary Table 1). Those excluded were the cumulative burden and willingness-to-pay modules, as well as waist measurement (Table 1 ). Table 1 Questions from the original HARDSHIP questionnaire excluded from this study. Original question number(s) Purpose of the question(s) Comment 51–57 Enquiry into cumulative burden (interference with education, career and earnings; reluctance to admit to headache [stigma]; perception of [lack of] overall control of headache). In order to shorten interview times, these questions on the long-term consequences of headache in participants’ lives were not prioritized. 67–74 Willingness to pay for effective headache treatment. This enquiry was expected to be of uncertain reliability because of the variable availability of, and access to, publicly funded health care or private insurance, and variable requirement for out-of-pocket payments. 89 Waist measurement in centimetres. This required a standardised measurement method, which could not be guaranteed through a telephone interview. A review of the Russian back-translation revealed improbable similarity to the original English questionnaire. It transpired that the back-translator had improperly consulted the published original rather than performed a genuine back-translation. This was rectified by engaging a new back-translator, who repeated the process according to protocol. Otherwise, several translation discrepancies (listed in full in Supplementary Table 2) were efficiently addressed. In the pilot study, interview duration ranged from 16 to 22 minutes. Feedback indicated that most questions were comprehensible, although those on well-being occasionally led to confusion (Table 2 ). Those about income and family planning caused some discomfort. We made minor adjustments to phrasing or simplified the language to enhance clarity and improve participants’ understanding. We also revised the introductory instructions to be more concise and explicit. Table 2 Comments from participants in the pilot study and actions in response. Comment Action “There were no difficult questions to understand or answer - everything was fine.” None “The questionnaire contained the same questions the doctor asked me during the visit.” None “I was uncomfortable answering the questions about my income and family planning; otherwise, I answered the questions without any problems. Everything was understandable.” None “I hope that such a questionnaire will prove that headache patients suffer daily. I am suffering, and I am not ashamed to talk about that. I want to end my headache, so I gladly support the research.” None “I did not know how to answer questions about my well-being; they confused me. I never think about that.” Introductory instruction improved. “The distinction between a professional and semi-professional, or skilled worker and a semi-skilled worker may be confusing.” Introductory instruction improved. The final questionnaires in each language, adapted, translated and revised, and their back-translations into English, are attached as Supplementary materials 1–4. Sample generation for main survey A total of 95,910 phone numbers were dialled to reach our target sample size of N = 2,100. Of these numbers, 52,979 had no recipient or were disconnected, 9,828 calls were unanswered, 8,404 returned a busy signal, 3,230 went to machines, faxes or modems, and 33 had damaged lines or poor communication (Fig. 1 ). Of the 21,436 individuals actually contacted, 2,980 did not meet the target demographic criteria (such as age or language) or were not residents of Latvia, 1,528 rescheduled the conversation outside the interviewers' working hours or outside the research time, and 551 were made to office numbers. Six individuals had already been surveyed (through another phone number). Consequently, there were 16,371 potential respondents. Of these, 11,866 refused to participate, 2,237 requested to reschedule twice, and 126 terminated the interview before usable data were gathered. One more potential respondent (female, aged 64 years, of Russian ethnicity, and residing in Riga) was excluded because of poor data collection by the interviewer. The result was 2,141 completed interviews, a participating proportion of 13.1% (2,141/16,371). The average interview duration was 17 minutes (range 4–55 min), longer for those reporting headache in the preceding year (average 20 minutes, range 11–55 min) than for those without headache (average 8 minutes; range 4–24 min). Representativeness of the sample Of the 2,141 participants, 1,033 (48.3%) were males and 1,108 (51.8%) females. Mean age of the sample was 43.3 years (SD = 13.0; median 43.0 years), similar among males (mean = 42.4; SD = 13.0; median = 42.0) and females (mean = 44.1; SD = 13.1; median = 44.0). Regional distribution was as follows: 33.7% from urban Riga, 19.6% from Riga suburbs, 9.2% from Vidzeme, 11.8% from Kurzeme, 11.9% from Zemgale and 13.8% from Latgale. A total of 1,523 (71.1%) participants were urban dwellers residing in Riga or other cities, the rest lived rurally. The majority of the participants were Latvians (61.9%), followed by Russians (24.6%) and other nationalities (13.5%). Table 3 compares these characteristics of the sample with those of the Latvian population aged 18–65 years. Gender (p = 0.12), age (p = 0.81), region (p = 0.88), habitation (p = 0.44) and nationality (p = 0.41) distributions of the sample were descriptively and statistically similar to those of the population. Level of education, on the other hand, differed significantly (p < 0.001) because of slight overrepresentation of people with higher education (40.6% vs 36.1%) and matching underrepresentation of people whose highest education level was secondary school (49.3% vs 53.7%). Table 3 Basic characteristics of the sample and the underlying population. Variable of interest Sample, N (%) Population, N* (%) Chi-square test Gender (df = 1, N = 2141) = 2.4, p = 0.12 Male Female 1033 (48.3) 1108 (51.8) 640,816 (49.9) 642,996 (50.1) Age (df = 4, N = 2141) = 1.6, p = 0.81 18–25 26–35 36–45 46–55 56–65 237 (11.1) 427 (19.9) 512 (23.9) 486 (22.7) 479 (22.4) 147,772 (11.5) 266,507 (20.8) 301,205 (23.5) 285,418 (22.2) 282,910 (22.0) Region (df = 5, N = 2141) = 1.7, p = 0.88 Riga Riga suburb Vidzeme Kurzeme Zemgale Latgale 722 (33.7) 420 (19.6) 196 (9.2) 253 (11.8) 254 (11.9) 296 (13.8) 425,929 (33.2) 261,220 (20.4) 120,570 (9.4) 156,136 (12.2) 149,930 (11.7) 170,027 (13.2) Habitation (df = 2, N = 2141) = 1.6, p = 0.44 Riga Other urban Rural 722 (33.7) 801 (37.4) 618 (28.9) 425,929 (33.2) 470,910 (36.7) 386,973 (30.1) Nationality (df = 2, N = 2141) = 1.8, p = 0.41 Latvian Russian Other 1,326 (61.9) 527 (24.6) 288 (13.5) 777,360 (60.6) 327,367 (25.5) 179,085 (14.0) Education (df = 2, N = 2141) = 20.2, p < 0.001 Primary school Secondary school Higher education 216 (10.1) 1,055 (49.3) 870 (40.6) 132,049 (10.3) 688,979 (53.7) 462,784 (36.1) *Data according to Office of Citizenship and Migration Affairs of Latvia [ 22 ]. Headache prevalence Of the 2,141 participants, 1,983 reported ever having headache, and 1,505 reported having headache during the previous year. These responses gave lifetime and 1-year prevalence estimates of 92.6% (95% confidence interval: 91.4–94.7%) and 70.3% (68.3–72.3%). Discussion This paper presents the methodology of Latvia's first population-based survey of headache disorders. We used a population-based cross-sectional quota and stratified sampling method to generate a sample representative of the Latvian population. We utilised double-forward followed by back translation, with intervening checks, to ensure accuracy and nuanced fidelity of the HARDSHIP questionnaire in Latvian and Russian languages. Comprehensibility and acceptability of the translated questionnaire were ensured through face-to-face interviews of headache patients in a pilot study. The main study was conducted via telephone interviews rather than face-to-face interactions. Our objective here was to assess whether this resource-conserving methodology was fit for its purpose of generating population-representative estimates of the burden of headache disorders in Latvia. The project originated in late 2019, with initial tasks planned for early 2020, coinciding with the first COVID-19 wave. This mandated the original choice of telephone interviews, with the ongoing pandemic creating a sustained preference for remote data collection. By September 2023, when funding was fully secured and COVID-19 was no longer a significant concern, we opted to maintain the original methodology to avoid the logistic and financial burdens of in-person interviews. Here, we introduce a general defence of CATI as an alternative to household visits and face-to-face interviews. Then, in the next paragraphs, we set out the problems, followed by justifications. The use of CATI, initially necessitated by the pandemic, offered several advantages apart from resource conservation. It allowed for automated quota control and adaptive question branching based on responses. For example, questions related to school-age children were only posed to participants who indicated they had children, avoiding unnecessary queries. Real-time data entry minimized transcription errors, enforced data entry restrictions, enabled automatic range validation, and provided immediate feedback to interviewers. All this enhanced data quality. Automated quota control was employed to ensure representativeness of the sample across key demographic variables, including gender, age, geographic region, settlement type (urban or rural), and primary language (Latvian or Russian), as well as a soft-limit stratification variable—education level. This approach ensured demographic balance at the acceptable cost of excluding otherwise eligible and willing participants due to stratification constraints. As illustrated in Fig. 1 , 2,980 individuals were excluded after initial screening because their demographic quota was filled. One of the primary findings, and limitations, of this study was the low participating proportion of 13.1%. Telephone interviews are prone to high refusal rates since calls are more easily terminated than face-to-face interactions [ 3 ]. The key question is whether our sample remained sufficiently representative of the target population. The fact that the sample was similar to the underlying population in terms of demographics, in particular gender ratio, is encouraging, but not sufficient to establish representativeness. Interest bias may still have been present. Statistically, we had an overrepresentation of individuals with higher education (40.6% vs. 36.1%), which may reflect a greater willingness among this group to participate in research. Whether this introduced any meaningful selection bias with regard to headache status is difficult to determine. Notably, recent HARDSHIP studies have shown no clear correlation between headache and education [ 23 – 27 ]. Morocco [ 25 ], Peru [ 26 ] and Benin [ 27 ]. The likelihood of interest bias is probably better assessed by examining headache prevalence. Within the sample, we found lifetime and 1-year prevalences of any headache of 92.6% and 70.3% respectively, which match findings from other recent studies (83.6–95.2% and 64.9–75.3% respectively) that also used the HARDSHIP questionnaire but had participating proportions above 90% [ 25 – 27 ]. This suggests that individuals with headache were not disproportionately more likely to participate. Strengths and limitations The limitation of low participation has been discussed. Despite this, the study had important strengths. The effective stratification method resulted in a sample that we believe was representative of the general population, despite the low participation. We employed a survey instrument with proven cross-cultural validity for conducting epidemiological headache surveys [ 4 ], and used bilingual materials, accommodating the substantial minority of Russian-speakers, thus enhancing accessibility and reliability. Furthermore, a pilot study was conducted to ensure comprehensibility and acceptability of the translated questionnaire. Conclusions Despite a suboptimal participating proportion of 13.1%, the sample appeared demographically representative of the Latvian population aged 18–65 years and, as far as could be judged, was not highly affected by interest bias. The estimates of headache prevalence aligned closely with those from other recent studies using HARDSHIP but with substantially higher participating proportions (> 90%). We believe the methodology was fit for purpose, and the sample generated can be used in an assessment of the burden of headache disorders in the general population of Latvia, a country where knowledge of this is wholly lacking. Abbreviations CATI computer-assisted telephone interview HALT Headache-Attributed Lost Time (index) HARDSHIP Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (questionnaire) ICHD International Classification of Headache Disorders LTB Lifting The Burden MOH medication-overuse headache NTNU Norwegian University of Science and Technology RSU Rīga Stradiņš University TTH tension-type headache WHO World Health Organization WHOQOL-8 World Health Organization 8-item quality of life questionnaire. Declarations Ethics approval and consent to participate The Rīga Stradiņš University Research Ethics Committee approved the study protocol, document no. 2-AFTER-4/254/2023No, on 13.03.2023. Before enrolment, all participants were informed of the nature and purpose of the study and gave oral consent. Consent for publication Not applicable. Availability of data and materials The consent forms signed by the pilot study participants were stored in the Headache unit of the Riga East University Hospital “Gaiļezers” Neurology and Neurosurgery Clinic during the study. After the study's completion, they will be stored in the Riga East University Hospital archive. The study participants' electronic questionnaires are anonymous. After the research concludes, the study data will be deposited in the RSU Dataverse data repository, which follows the FAIR principles of research data management. Competing interests TJS and AKH are Directors and Trustees of Lifting The Burden . TJS is an associate editor of the Journal of Headache and Pain, and AKH is a member of its Editorial Board. Funding Funding was provided by the Neurological Disease Research Foundation. Author ’ s contributions LM, GK and IG conceptualised and designed the study and developed the research methodology. LM, GK, and MA were responsible for securing funding and resources for the study. GK, IG, and MA oversaw the study's execution. TJS provided advice and guidance throughout the project. AKH conducted the statistical analysis. LM drafted the manuscript. All authors reviewed the manuscript and approved the final version. Acknowledgements Not applicable. Authors’ information Not applicable. References Steiner TJ, Birbeck GL, Jensen RH, Martelletti P, Stovner LJ, Uluduz D, et al. The global campaign turns 18: a brief review of its activities and achievements. J Headache Pain. 2022;23:49. Steiner TJ, Gil-Gouveia R, Husøy AK, Jensen R, Katsarava Z, Martelletti P, et al. The global campaign against headache, aged 21: a critical self-appraisal, and plans for phase 2. J Headache Pain. 2025;26:59. Stovner LJ, Al Jumah M, Birbeck GL, Gururaj G, Jensen R, Katsarava Z, et al. 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Supplementary Files attachmentslm.docx supplementarytablesLM.docx Cite Share Download PDF Status: Published Journal Publication published 17 Dec, 2025 Read the published version in Archives of Public Health → Version 1 posted Editorial decision: Revision requested 12 Oct, 2025 Reviews received at journal 12 Sep, 2025 Reviewers agreed at journal 25 Aug, 2025 Reviewers invited by journal 22 Aug, 2025 Editor assigned by journal 17 Jul, 2025 Submission checks completed at journal 17 Jul, 2025 First submitted to journal 03 Jul, 2025 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-7040119","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":505077835,"identity":"240b81f1-703d-4d54-81f8-5dba834c2247","order_by":0,"name":"Liga Meksa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8klEQVRIiWNgGAWjYBACPmYgkQDEEkB84AOQYGMnoIUNWcvBGTARvFpgDJAWZh4Qi6AWdvaLHx4wbJOT7D/88LDNr23yQKcyfviYg89hPMUSCQy3jaUl0gwO5/bdNmxjZmCWnLkNr5YEkJbEeRIMQC09txmBWtiYefFrSf4B1FI/j//4h8OWPbftidDCfgxkS4I0Q47BYYYftxOJsYXNIsHgtuHMGTkFB3sbbie3MTM24/ULP//xxzd/VNyWlzh/fPOHH39u285vbz744SMeLQwMPAYMDAZQNmMbmGzApx4I2B8gcf4QUDwKRsEoGAUjEgAAJOtMOzbVLewAAAAASUVORK5CYII=","orcid":"","institution":"Riga East University Hospital clinic “Gaiļezers”","correspondingAuthor":true,"prefix":"","firstName":"Liga","middleName":"","lastName":"Meksa","suffix":""},{"id":505077836,"identity":"8aa12db5-7bf2-4347-b709-3de36d9b0099","order_by":1,"name":"Mihails Arons","email":"","orcid":"","institution":"Riga East University Hospital Clinic","correspondingAuthor":false,"prefix":"","firstName":"Mihails","middleName":"","lastName":"Arons","suffix":""},{"id":505077837,"identity":"6b211ae2-b87b-4adf-9efe-a280a063f6af","order_by":2,"name":"Andreas Kattem Husøy","email":"","orcid":"","institution":"NorHead, NTNU Norwegian University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Andreas","middleName":"Kattem","lastName":"Husøy","suffix":""},{"id":505077838,"identity":"70b3af78-f355-42d1-8cb5-6ab1d3720a18","order_by":3,"name":"Inese Gobina","email":"","orcid":"","institution":"Riga Stradiņš University","correspondingAuthor":false,"prefix":"","firstName":"Inese","middleName":"","lastName":"Gobina","suffix":""},{"id":505077839,"identity":"e2c305d0-9c38-4243-bbc4-be59cb6693d3","order_by":4,"name":"Guntis Karelis","email":"","orcid":"","institution":"Riga Stradiņš University","correspondingAuthor":false,"prefix":"","firstName":"Guntis","middleName":"","lastName":"Karelis","suffix":""},{"id":505077840,"identity":"37f6855d-4377-4a41-ad54-b74f7bedca1c","order_by":5,"name":"Timothy J Steiner","email":"","orcid":"","institution":"NorHead, NTNU Norwegian University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Timothy","middleName":"J","lastName":"Steiner","suffix":""}],"badges":[],"createdAt":"2025-07-03 16:23:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7040119/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7040119/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13690-025-01811-0","type":"published","date":"2025-12-17T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90364820,"identity":"f8a41536-d5fc-471d-844a-4e91c2f76539","added_by":"auto","created_at":"2025-09-02 02:21:45","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":103674,"visible":true,"origin":"","legend":"\u003cp\u003eLegend not included with this version\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7040119/v1/055b30feb6f2a1585451a535.png"},{"id":98813942,"identity":"51c7ee76-002e-4a67-bc6f-bbfae053eabb","added_by":"auto","created_at":"2025-12-22 16:08:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":894526,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7040119/v1/daab73da-354d-4276-b2a1-f8e9b4baf949.pdf"},{"id":90364118,"identity":"1ab97d3f-c4e5-4994-a749-f21a894ab1e7","added_by":"auto","created_at":"2025-09-02 02:13:45","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":82097,"visible":true,"origin":"","legend":"","description":"","filename":"attachmentslm.docx","url":"https://assets-eu.researchsquare.com/files/rs-7040119/v1/14069543113ab27ff63f5190.docx"},{"id":90364818,"identity":"f03b3b79-00c9-420d-b0c2-0a3808eb77be","added_by":"auto","created_at":"2025-09-02 02:21:45","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":19134,"visible":true,"origin":"","legend":"","description":"","filename":"supplementarytablesLM.docx","url":"https://assets-eu.researchsquare.com/files/rs-7040119/v1/bd20ea4cf91aaff4b016318b.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Methodology of a population-based survey of headache disorders among adults in Latvia","fulltext":[{"header":"Contributions to the literature","content":"\u003cul\u003e\n \u003cli\u003eThis is the first population-based study on headache disorders conducted in Latvia.\u003c/li\u003e\n \u003cli\u003eIt fills a geographical gap in the Global Campaign against Headache, contributing new data from an underrepresented European region.\u003c/li\u003e\n \u003cli\u003eThe study provides a tested and culturally adapted version of the HARDSHIP questionnaire in both Latvian and Russian.\u003c/li\u003e\n \u003cli\u003eIt demonstrates the feasibility of using computer-assisted telephone interviews for headache epidemiology in multilingual populations.\u003c/li\u003e\n \u003cli\u003eThe findings support future public health planning and policy development for headache care in Latvia and similar settings.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Background","content":"\u003cp\u003eIn 2014, the Global Campaign against Headache [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], led by the UK-based non-governmental organisation \u003cem\u003eLifting The Burden\u003c/em\u003e (LTB), published guidelines for conducting and reporting population-based studies on headache disorders [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Along with these, and recommended in the guidelines, was the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. HARDSHIP is an instrument for assessing prevalence and attributable burden of the headache disorders of public health importance. It has been used in diverse populations in various geographical regions, with adaptations to ensure cultural and contextual relevance while preserving its reliability and validity [\u003cspan additionalcitationids=\"CR6 CR7 CR8 CR9 CR10 CR11 CR12 CR13 CR14\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e–\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Although used in Russia [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and Lithuania [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], these methods have not been applied to Latvia's population. Neither have other studies examined the prevalence and burden of headache disorders in the general population of this country.\u003c/p\u003e\u003cp\u003eWe report here the adaptation of the HARDSHIP questionnaire to a Latvian setting, including translation into Latvian, the official state language, and Russian, the most widely spoken minority language. The survey method is described in detail, along with the challenges encountered during the study. We also present a detailed account of the essential characteristics of the sample, and comment on its validity as a representative sample of the population of interest.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cb\u003eStudy design\u003c/b\u003e\u003c/p\u003e\u003cp\u003e This was a population-based cross-sectional survey that utilised a structured questionnaire in telephone interviews, engaging participants through computer-assisted random-digit dialling. A pilot study was conducted to assess its feasibility.\u003c/p\u003e\u003cp\u003e\u003cb\u003eQuestionnaire adaptation and translation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWe adapted the HARDSHIP questionnaire for use in Latvia, selecting questions for inclusion according to its modular design [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This adapted version was translated into Latvian, the official state language, and into Russian, since Russian speakers constitute the most prevalent minority (37.7% of the Latvian population [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]). To ensure linguistic and cultural appropriateness, we followed the translation protocol for hybrid documents developed by the Global Campaign [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Two native speakers of Latvian or Russian, bilingual in English, one a headache expert, DJ (Latvian) or AK (Russian), and the other a professional translator, MN (Latvian) or LZ (Russian), independently performed the translations. Any discrepancies were resolved through discussion between the headache experts, the translators and the study coordinator (LM), creating a forward translation agreed by consensus. Literal back-translations of these, from each language into English, were performed by professional translators (BK [Latvian] or DS [Russian]). Each of these was reviewed and compared item by item against the original questionnaire by its principal author (TJS). When conceptual equivalence appeared to have been lost in translation or meaning distorted, the forward translations were amended accordingly.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePilot study\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe pilot study was conducted among a convenience sample of 30 patients (15 Latvian speakers and 15 Russian speakers) immediately following their initial consultations and diagnosis of migraine, tension-type headache (TTH) or medication-overuse headache (MOH) according to the criteria of the International Classification of Headache Disorders third edition (ICHD-3) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Face-to-face interviews assessed the comprehensibility and acceptability of the questionnaire and the duration of interviews. Questions or response options that were not immediately understood were repeated slowly, with requests to choose the most appropriate option for the latter.\u003c/p\u003e\u003cp\u003eParticipants were actively encouraged to voice their concerns about the questionnaire. Amendments were made in response to these and any other difficulties that became apparent.\u003c/p\u003e\u003cp\u003eParticipants in the pilot study were not included in the main study.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMain study\u003c/b\u003e\u003c/p\u003e\u003cp\u003eData were collected from October 30th 2023 to January 24th 2024.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSampling\u003c/b\u003e\u003c/p\u003e\u003cp\u003eWe employed a population-based, cross-sectional design using a stratified quota sampling method to ensure representativeness of the Latvian population. To facilitate random selection, we implemented a random-digit dialling approach, incorporating the national country code (+ 371) [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This method enabled the generation of seven- and eight-digit numbers across all relevant landline and mobile prefixes, in accordance with the Latvian telephone numbering plan. Dialling continued iteratively until the target sample size was reached, thereby supporting the reliability and generalisability of our findings.\u003c/p\u003e\u003cp\u003eFollowing established methodological guidelines [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], we aimed for a sample size of 2,100 respondents, which was considered sufficient to balance statistical power with the constraints of available resources. This target was proportionally distributed according to national population data [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], with the aim of ensuring appropriate demographic representation. To achieve this, we applied hard-limit stratification criteria for key demographic domains: gender, age, geographic region, settlement type (urban or rural), and primary language (Latvian or Russian), in accordance with national census data [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Education level served as a soft-limit stratification variable, acting more as a guideline for recruitment rather than a strict requirement. To avoid increasing the study's costs, we were satisfied with reaching 94% of the education quota limit.\u003c/p\u003e\u003cp\u003e\u003cb\u003eEngagement with participants, and data collection\u003c/b\u003e\u003c/p\u003e\u003cp\u003e When a phone call was successfully connected, the interviewer explained that participation was voluntary and confidential, and asked for consent to proceed with the interview. Only then were the inclusion criteria applied (aged 18–65 years; resident in Latvia for at least the preceding 12 months; cognitively able to understand and respond to the study questions, and able to communicate effectively in Latvian or Russian). When these were fulfilled, the stratification questions were asked, and the interview continued.\u003c/p\u003e\u003cp\u003eInterviews were conducted by 24 professional interviewers with experience in statistical market research data collection and medical research, although without specific expertise in headache disorders. All participants underwent training that covered the study objectives, research methodology, interview protocols and an overview of typical primary and secondary headaches. Continuous support and guidance were available from the principal investigator throughout the data collection period.\u003c/p\u003e\u003cp\u003eThe interviews were programmed using the NIPO Computer-Assisted Telephone Interviewing (CATI)/Web Fieldwork system. Real-time data entry by the interviewers obviated transcription errors, while built-in measures, ensuring adherence to established formats, promoted complete and accurate data entry. Targeted data entry restrictions and automatic range validation ensured user inputs aligned with question structure, relevant periods and feasible ranges. The system issued immediate feedback to interviewers and provided prompts for correction when entries breached these. Conditional logic made specific fields mandatory in accordance with prior responses.\u003c/p\u003e\u003cp\u003e\u003cb\u003eHeadache diagnoses\u003c/b\u003e\u003c/p\u003e\u003cp\u003eHeadache diagnoses were determined using the HARDSHIP diagnostic algorithm applying modified ICHD-3 criteria [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Only participants reporting headache in the past year were diagnosed. Those who reported ≥ 15 headache days/month (H15+) were classified as probable MOH (pMOH) when also reporting medication use on ≥ 10 days/month and otherwise as other H15+. Those with \u0026lt; 15 headache days/month were hierarchically classified according to reported symptoms (of their most bothersome headache type when multiple types were present) as definite migraine, definite TTH, probable migraine or probable TTH. Participants not fulfilling any of these diagnostic criteria were classified as having unclassified headache.\u003c/p\u003e\u003cp\u003eThe enquiry also included headache on the day preceding the interview (headache yesterday [HY]). This was not diagnosed because ICHD-3 criteria apply to disorders, not single episodes.\u003c/p\u003e\u003cp\u003e\u003cb\u003eAnalysis\u003c/b\u003e\u003c/p\u003e\u003cp\u003eUsing chi-squared tests, we compared the study sample with the general adult population of Latvia according to gender, nationality, age, region, type of residence and education.\u003c/p\u003e\u003cp\u003eStatistical analyses were performed using RStudio version 2024.04.0 + 735.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eAdaptation, translation and pilot study\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAdaptations were minimal: almost all questions from the original HARDSHIP questionnaire [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] were deemed appropriate and included (Supplementary Table\u0026nbsp;1). Those excluded were the cumulative burden and willingness-to-pay modules, as well as waist measurement (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\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\u003eQuestions from the original HARDSHIP questionnaire excluded from this study.\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\u003eOriginal question number(s)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePurpose of the question(s)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eComment\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e51\u0026ndash;57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEnquiry into cumulative burden (interference with education, career and earnings; reluctance to admit to headache [stigma]; perception of [lack of] overall control of headache).\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eIn order to shorten interview times, these questions on the long-term consequences of headache in participants\u0026rsquo; lives were not prioritized.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e67\u0026ndash;74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWillingness to pay for effective headache treatment.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThis enquiry was expected to be of uncertain reliability because of the variable availability of, and access to, publicly funded health care or private insurance, and variable requirement for out-of-pocket payments.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWaist measurement in centimetres.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThis required a standardised measurement method, which could not be guaranteed through a telephone interview.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eA review of the Russian back-translation revealed improbable similarity to the original English questionnaire. It transpired that the back-translator had improperly consulted the published original rather than performed a genuine back-translation. This was rectified by engaging a new back-translator, who repeated the process according to protocol.\u003c/p\u003e\u003cp\u003eOtherwise, several translation discrepancies (listed in full in Supplementary Table\u0026nbsp;2) were efficiently addressed.\u003c/p\u003e\u003cp\u003eIn the pilot study, interview duration ranged from 16 to 22 minutes. Feedback indicated that most questions were comprehensible, although those on well-being occasionally led to confusion (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Those about income and family planning caused some discomfort. We made minor adjustments to phrasing or simplified the language to enhance clarity and improve participants\u0026rsquo; understanding. We also revised the introductory instructions to be more concise and explicit.\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\u003eComments from participants in the pilot study and actions in response.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eComment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAction\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;There were no difficult questions to understand or answer - everything was fine.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;The questionnaire contained the same questions the doctor asked me during the visit.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;I was uncomfortable answering the questions about my income and family planning; otherwise, I answered the questions without any problems. Everything was understandable.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;I hope that such a questionnaire will prove that headache patients suffer daily. I am suffering, and I am not ashamed to talk about that. I want to end my headache, so I gladly support the research.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;I did not know how to answer questions about my well-being; they confused me. I never think about that.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIntroductory instruction improved.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ldquo;The distinction between a professional and semi-professional, or skilled worker and a semi-skilled worker may be confusing.\u0026rdquo;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIntroductory instruction improved.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe final questionnaires in each language, adapted, translated and revised, and their back-translations into English, are attached as Supplementary materials 1\u0026ndash;4.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSample generation for main survey\u003c/b\u003e\u003c/p\u003e\u003cp\u003eA total of 95,910 phone numbers were dialled to reach our target sample size of N\u0026thinsp;=\u0026thinsp;2,100. Of these numbers, 52,979 had no recipient or were disconnected, 9,828 calls were unanswered, 8,404 returned a busy signal, 3,230 went to machines, faxes or modems, and 33 had damaged lines or poor communication (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Of the 21,436 individuals actually contacted, 2,980 did not meet the target demographic criteria (such as age or language) or were not residents of Latvia, 1,528 rescheduled the conversation outside the interviewers' working hours or outside the research time, and 551 were made to office numbers. Six individuals had already been surveyed (through another phone number).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eConsequently, there were 16,371 potential respondents. Of these, 11,866 refused to participate, 2,237 requested to reschedule twice, and 126 terminated the interview before usable data were gathered. One more potential respondent (female, aged 64 years, of Russian ethnicity, and residing in Riga) was excluded because of poor data collection by the interviewer. The result was 2,141 completed interviews, a participating proportion of 13.1% (2,141/16,371).\u003c/p\u003e\u003cp\u003eThe average interview duration was 17 minutes (range 4\u0026ndash;55 min), longer for those reporting headache in the preceding year (average 20 minutes, range 11\u0026ndash;55 min) than for those without headache (average 8 minutes; range 4\u0026ndash;24 min).\u003c/p\u003e\u003cp\u003e\u003cb\u003eRepresentativeness of the sample\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOf the 2,141 participants, 1,033 (48.3%) were males and 1,108 (51.8%) females. Mean age of the sample was 43.3 years (SD\u0026thinsp;=\u0026thinsp;13.0; median 43.0 years), similar among males (mean\u0026thinsp;=\u0026thinsp;42.4; SD\u0026thinsp;=\u0026thinsp;13.0; median\u0026thinsp;=\u0026thinsp;42.0) and females (mean\u0026thinsp;=\u0026thinsp;44.1; SD\u0026thinsp;=\u0026thinsp;13.1; median\u0026thinsp;=\u0026thinsp;44.0).\u003c/p\u003e\u003cp\u003eRegional distribution was as follows: 33.7% from urban Riga, 19.6% from Riga suburbs, 9.2% from Vidzeme, 11.8% from Kurzeme, 11.9% from Zemgale and 13.8% from Latgale. A total of 1,523 (71.1%) participants were urban dwellers residing in Riga or other cities, the rest lived rurally. The majority of the participants were Latvians (61.9%), followed by Russians (24.6%) and other nationalities (13.5%).\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e compares these characteristics of the sample with those of the Latvian population aged 18\u0026ndash;65 years. Gender (p\u0026thinsp;=\u0026thinsp;0.12), age (p\u0026thinsp;=\u0026thinsp;0.81), region (p\u0026thinsp;=\u0026thinsp;0.88), habitation (p\u0026thinsp;=\u0026thinsp;0.44) and nationality (p\u0026thinsp;=\u0026thinsp;0.41) distributions of the sample were descriptively and statistically similar to those of the population. Level of education, on the other hand, differed significantly (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) because of slight overrepresentation of people with higher education (40.6% vs 36.1%) and matching underrepresentation of people whose highest education level was secondary school (49.3% vs 53.7%).\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\u003eBasic characteristics of the sample and the underlying population.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eVariable of interest\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSample, N (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePopulation, N* (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eChi-square test\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eGender\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;1, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;2.4, p\u0026thinsp;=\u0026thinsp;0.12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1033 (48.3)\u003c/p\u003e\u003cp\u003e1108 (51.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e640,816 (49.9)\u003c/p\u003e\u003cp\u003e642,996 (50.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;4, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;1.6, p\u0026thinsp;=\u0026thinsp;0.81\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18\u0026ndash;25\u003c/p\u003e\u003cp\u003e26\u0026ndash;35\u003c/p\u003e\u003cp\u003e36\u0026ndash;45\u003c/p\u003e\u003cp\u003e46\u0026ndash;55\u003c/p\u003e\u003cp\u003e56\u0026ndash;65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e237 (11.1)\u003c/p\u003e\u003cp\u003e427 (19.9)\u003c/p\u003e\u003cp\u003e512 (23.9)\u003c/p\u003e\u003cp\u003e486 (22.7)\u003c/p\u003e\u003cp\u003e479 (22.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e147,772 (11.5)\u003c/p\u003e\u003cp\u003e266,507 (20.8)\u003c/p\u003e\u003cp\u003e301,205 (23.5)\u003c/p\u003e\u003cp\u003e285,418 (22.2)\u003c/p\u003e\u003cp\u003e282,910 (22.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eRegion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;5, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;1.7, p\u0026thinsp;=\u0026thinsp;0.88\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRiga\u003c/p\u003e\u003cp\u003eRiga suburb\u003c/p\u003e\u003cp\u003eVidzeme\u003c/p\u003e\u003cp\u003eKurzeme\u003c/p\u003e\u003cp\u003eZemgale\u003c/p\u003e\u003cp\u003eLatgale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e722 (33.7)\u003c/p\u003e\u003cp\u003e420 (19.6)\u003c/p\u003e\u003cp\u003e196 (9.2)\u003c/p\u003e\u003cp\u003e253 (11.8)\u003c/p\u003e\u003cp\u003e254 (11.9)\u003c/p\u003e\u003cp\u003e296 (13.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e425,929 (33.2)\u003c/p\u003e\u003cp\u003e261,220 (20.4)\u003c/p\u003e\u003cp\u003e120,570 (9.4)\u003c/p\u003e\u003cp\u003e156,136 (12.2)\u003c/p\u003e\u003cp\u003e149,930 (11.7)\u003c/p\u003e\u003cp\u003e170,027 (13.2)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eHabitation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;2, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;1.6, p\u0026thinsp;=\u0026thinsp;0.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRiga\u003c/p\u003e\u003cp\u003eOther urban\u003c/p\u003e\u003cp\u003eRural\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e722 (33.7)\u003c/p\u003e\u003cp\u003e801 (37.4)\u003c/p\u003e\u003cp\u003e618 (28.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e425,929 (33.2)\u003c/p\u003e\u003cp\u003e470,910 (36.7)\u003c/p\u003e\u003cp\u003e386,973 (30.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eNationality\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;2, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;1.8, p\u0026thinsp;=\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLatvian\u003c/p\u003e\u003cp\u003eRussian\u003c/p\u003e\u003cp\u003eOther\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1,326 (61.9)\u003c/p\u003e\u003cp\u003e527 (24.6)\u003c/p\u003e\u003cp\u003e288 (13.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e777,360 (60.6)\u003c/p\u003e\u003cp\u003e327,367 (25.5)\u003c/p\u003e\u003cp\u003e179,085 (14.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eEducation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e(df\u0026thinsp;=\u0026thinsp;2, N\u0026thinsp;=\u0026thinsp;2141)\u0026thinsp;=\u0026thinsp;20.2, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePrimary school\u003c/p\u003e\u003cp\u003eSecondary school\u003c/p\u003e\u003cp\u003eHigher education\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e216 (10.1)\u003c/p\u003e\u003cp\u003e1,055 (49.3)\u003c/p\u003e\u003cp\u003e870 (40.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e132,049 (10.3)\u003c/p\u003e\u003cp\u003e688,979 (53.7)\u003c/p\u003e\u003cp\u003e462,784 (36.1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e*Data according to Office of Citizenship and Migration Affairs of Latvia [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cb\u003eHeadache prevalence\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOf the 2,141 participants, 1,983 reported ever having headache, and 1,505 reported having headache during the previous year. These responses gave lifetime and 1-year prevalence estimates of 92.6% (95% confidence interval: 91.4\u0026ndash;94.7%) and 70.3% (68.3\u0026ndash;72.3%).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis paper presents the methodology of Latvia's first population-based survey of headache disorders. We used a population-based cross-sectional quota and stratified sampling method to generate a sample representative of the Latvian population. We utilised double-forward followed by back translation, with intervening checks, to ensure accuracy and nuanced fidelity of the HARDSHIP questionnaire in Latvian and Russian languages. Comprehensibility and acceptability of the translated questionnaire were ensured through face-to-face interviews of headache patients in a pilot study. The main study was conducted via telephone interviews rather than face-to-face interactions.\u003c/p\u003e\u003cp\u003eOur objective here was to assess whether this resource-conserving methodology was fit for its purpose of generating population-representative estimates of the burden of headache disorders in Latvia.\u003c/p\u003e\u003cp\u003eThe project originated in late 2019, with initial tasks planned for early 2020, coinciding with the first COVID-19 wave. This mandated the original choice of telephone interviews, with the ongoing pandemic creating a sustained preference for remote data collection. By September 2023, when funding was fully secured and COVID-19 was no longer a significant concern, we opted to maintain the original methodology to avoid the logistic and financial burdens of in-person interviews.\u003c/p\u003e\u003cp\u003eHere, we introduce a general defence of CATI as an alternative to household visits and face-to-face interviews. Then, in the next paragraphs, we set out the problems, followed by justifications.\u003c/p\u003e\u003cp\u003eThe use of CATI, initially necessitated by the pandemic, offered several advantages apart from resource conservation. It allowed for automated quota control and adaptive question branching based on responses. For example, questions related to school-age children were only posed to participants who indicated they had children, avoiding unnecessary queries. Real-time data entry minimized transcription errors, enforced data entry restrictions, enabled automatic range validation, and provided immediate feedback to interviewers. All this enhanced data quality.\u003c/p\u003e\u003cp\u003eAutomated quota control was employed to ensure representativeness of the sample across key demographic variables, including gender, age, geographic region, settlement type (urban or rural), and primary language (Latvian or Russian), as well as a soft-limit stratification variable\u0026mdash;education level. This approach ensured demographic balance at the acceptable cost of excluding otherwise eligible and willing participants due to stratification constraints. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, 2,980 individuals were excluded after initial screening because their demographic quota was filled.\u003c/p\u003e\u003cp\u003eOne of the primary findings, and limitations, of this study was the low participating proportion of 13.1%. Telephone interviews are prone to high refusal rates since calls are more easily terminated than face-to-face interactions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The key question is whether our sample remained sufficiently representative of the target population. The fact that the sample was similar to the underlying population in terms of demographics, in particular gender ratio, is encouraging, but not sufficient to establish representativeness. Interest bias may still have been present. Statistically, we had an overrepresentation of individuals with higher education (40.6% vs. 36.1%), which may reflect a greater willingness among this group to participate in research. Whether this introduced any meaningful selection bias with regard to headache status is difficult to determine. Notably, recent HARDSHIP studies have shown no clear correlation between headache and education [\u003cspan additionalcitationids=\"CR24 CR25 CR26\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Morocco [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], Peru [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] and Benin [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe likelihood of interest bias is probably better assessed by examining headache prevalence. Within the sample, we found lifetime and 1-year prevalences of any headache of 92.6% and 70.3% respectively, which match findings from other recent studies (83.6\u0026ndash;95.2% and 64.9\u0026ndash;75.3% respectively) that also used the HARDSHIP questionnaire but had participating proportions above 90% [\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This suggests that individuals with headache were not disproportionately more likely to participate.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStrengths and limitations\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe limitation of low participation has been discussed.\u003c/p\u003e\u003cp\u003eDespite this, the study had important strengths. The effective stratification method resulted in a sample that we believe was representative of the general population, despite the low participation. We employed a survey instrument with proven cross-cultural validity for conducting epidemiological headache surveys [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and used bilingual materials, accommodating the substantial minority of Russian-speakers, thus enhancing accessibility and reliability. Furthermore, a pilot study was conducted to ensure comprehensibility and acceptability of the translated questionnaire.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eDespite a suboptimal participating proportion of 13.1%, the sample appeared demographically representative of the Latvian population aged 18\u0026ndash;65 years and, as far as could be judged, was not highly affected by interest bias. The estimates of headache prevalence aligned closely with those from other recent studies using HARDSHIP but with substantially higher participating proportions (\u0026gt;\u0026thinsp;90%). We believe the methodology was fit for purpose, and the sample generated can be used in an assessment of the burden of headache disorders in the general population of Latvia, a country where knowledge of this is wholly lacking.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCATI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ecomputer-assisted telephone interview\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eHALT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eHeadache-Attributed Lost Time (index)\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eHARDSHIP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eHeadache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (questionnaire)\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICHD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInternational Classification of Headache Disorders\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLTB\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003e\u003cem\u003eLifting The Burden\u003c/em\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMOH\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003emedication-overuse headache\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eNTNU\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eNorwegian University of Science and Technology\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRSU\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eRīga Stradiņš University\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTTH\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003etension-type headache\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eWHO\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eWorld Health Organization\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eWHOQOL-8\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eWorld Health Organization 8-item quality of life questionnaire.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Rīga Stradiņš University Research Ethics Committee approved the study protocol, document no. 2-AFTER-4/254/2023No, on 13.03.2023. Before enrolment, all participants were informed of the nature and purpose of the study and gave oral consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe consent forms signed by the pilot study participants were stored in the Headache unit of the Riga East University Hospital “Gaiļezers” Neurology and Neurosurgery Clinic during the study. After the study's completion, they will be stored in the Riga East University Hospital archive.\u003c/p\u003e\n\u003cp\u003eThe study participants' electronic questionnaires are anonymous. After the research concludes, the study data will be deposited in the RSU Dataverse data repository, which follows the FAIR principles of research data management.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTJS and AKH are Directors and Trustees of \u003cem\u003eLifting\u003c/em\u003e \u003cem\u003eThe\u003c/em\u003e \u003cem\u003eBurden\u003c/em\u003e. TJS is an associate editor of \u003cem\u003ethe\u003c/em\u003e \u003cem\u003eJournal\u003c/em\u003e \u003cem\u003eof\u003c/em\u003e \u003cem\u003eHeadache\u003c/em\u003e \u003cem\u003eand\u003c/em\u003e \u003cem\u003ePain,\u003c/em\u003e and AKH is a member of its Editorial Board.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFunding was provided by the Neurological Disease Research Foundation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthor\u003c/em\u003e\u003c/strong\u003e’\u003cstrong\u003e\u003cem\u003es contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLM, GK and IG conceptualised and designed the study and developed the research methodology. LM, GK, and MA were responsible for securing funding and resources for the study. GK, IG, and MA oversaw the study's execution. TJS provided advice and guidance throughout the project. AKH conducted the statistical analysis. LM drafted the manuscript. All authors reviewed the manuscript and approved the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgements\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthors’ information\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSteiner TJ, Birbeck GL, Jensen RH, Martelletti P, Stovner LJ, Uluduz D, et al. The global campaign turns 18: a brief review of its activities and achievements. J Headache Pain. 2022;23:49.\u003c/li\u003e\n\u003cli\u003eSteiner TJ, Gil-Gouveia R, Hus\u0026oslash;y AK, Jensen R, Katsarava Z, Martelletti P, et al. The global campaign against headache, aged 21: a critical self-appraisal, and plans for phase 2. J Headache Pain. 2025;26:59.\u003c/li\u003e\n\u003cli\u003eStovner LJ, Al Jumah M, Birbeck GL, Gururaj G, Jensen R, Katsarava Z, et al. The methodology of population surveys of headache prevalence, burden and cost: principles and recommendations from the Global Campaign against Headache. J Headache Pain. 2014;15:5.\u003c/li\u003e\n\u003cli\u003eSteiner TJ, Gururaj G, Andr\u0026eacute;e C, Katsarava Z, Ayzenberg I, Yu SY, et al. Diagnosis, prevalence estimation and burden measurement in population surveys of headache: presenting the HARDSHIP questionnaire. J Headache Pain. 2014;15:3.\u003c/li\u003e\n\u003cli\u003eKukava M, Dzagnidze A, Janelidze M, Mirvelashvili E, Djibuti M, Fritsche G, et al. Validation of a Georgian language headache questionnaire in a population-based sample. J Headache Pain. 2007;8:321-4.\u003c/li\u003e\n\u003cli\u003eKatsarava Z, Dzagnidze A, Kukava M, Mirvelashvili E, Djibuti M, Janelidze M, et al. Primary headache disorders in the republic of Georgia: prevalence and risk factors. Neurology. 2009;73:1796-803.\u003c/li\u003e\n\u003cli\u003eCiobanu L, Corcea G, Craciun C, Katsarava Z, Moldovanu I, Moldovanu I, et al. The prevalence of headache disorders in the republic of Moldova: a population-based study. Cephalalgia. 2007;27:673.\u003c/li\u003e\n\u003cli\u003eAyzenberg I, Katsarava Z, Mathalikov R, Chernysh M, Osipova V, Tabeeva G, et al. The burden of headache in Russia: validation of the diagnostic questionnaire in a population-based sample. Eur J Neurol. 2011;18:454-9.\u003c/li\u003e\n\u003cli\u003eAyzenberg I, Katsarava Z, Sborowski A, Chernysh M, Osipova V, Tabeeva G, et al. The prevalence of primary headache disorders in Russia: a countrywide survey. Cephalalgia. 2012;32:373-81.\u003c/li\u003e\n\u003cli\u003eYu S, Liu R, Zhao G, Yang X, Qiao X, Feng J, et al. The prevalence and burden of primary headaches in China: a population-based door-to-door survey. Headache. 2012;52:582-91.\u003c/li\u003e\n\u003cli\u003eRao GN, Kulkarni GB, Gururaj G, Rajesh K, Subbakrishna DK, Steiner TJ, et al. The burden of headache disorders in India: methodology and questionnaire validation for a community-based survey in Karnataka state. J Headache Pain. 2012;13:543-50.\u003c/li\u003e\n\u003cli\u003eKulkarni GB, Rao GN, Gururaj G, Stovner LJ, Steiner TJ. Headache disorders and public ill-health in India: prevalence estimates in Karnataka state. J Headache Pain. 2015;16:67.\u003c/li\u003e\n\u003cli\u003eHerekar AD, Herekar AA, Ahmad A, Uqaili UL, Ahmed B, Effendi J, et al. The burden of headache disorders in Pakistan: methodology of a population-based nationwide study, and questionnaire validation. J Headache Pain. 2013;14:73.\u003c/li\u003e\n\u003cli\u003eHerekar AA, Ahmad A, Uqaili UL, Ahmed B, Effendi J, Alvi SZ, et al. Primary headache disorders in the adult general population of Pakistan - a cross sectional nationwide prevalence survey. J Headache Pain. 2017;18:28.\u003c/li\u003e\n\u003cli\u003eRastenytė D, Mickevičienė D, Stovner LJ, Thomas H, Andr\u0026eacute;e C, Steiner TJ. Prevalence and burden of headache disorders in Lithuania and their public-health and policy implications: a population-based study within the Eurolight project. J Headache Pain. 2017;18:53.\u003c/li\u003e\n\u003cli\u003eCentral Statistical Bureau of Latvia. Latvian is mother tongue of 60.8 % of the population of Latvia. 2017. https://stat.gov.lv/en/statistics-themes/education/level-education/press-releases/1911-latvian-mother-tongue-608. Accessed 19 Jul 2024.\u003c/li\u003e\n\u003cli\u003ePeters M, Bertelote J, Houchin C, Kandoura T, Steiner T. Translation protocols. J Headache Pain. 2007;8:S40-7.\u003c/li\u003e\n\u003cli\u003eHeadache Classification Committee of the International Headache Society. The international classification of headache disorders, 3rd edition. Cephalalgia. 2013;33:629-808.\u003c/li\u003e\n\u003cli\u003eCabinet of Ministers Regulation. \u003cspan dir=\"RTL\"\u003e\u0026ldquo;\u003c/span\u003eNoteikumi par nacionālo numerācijas plānu\u0026quot;. Publicēts oficiālajā laikrakstā \u0026quot;latvijas vēstnesis\u0026rdquo;. 2008. https://www.vestnesis.lv/ta/id/180527-noteikumi-par-nacionalo-numeracijas-planu. Accessed 3 Sept 2008.\u003c/li\u003e\n\u003cli\u003eJūnija L. Grozījumi administratīvo teritoriju un apdzīvoto vietu likumā. 2021. https://likumi.lv/ta/id/323631. Accessed 3 Jun 2021.\u003c/li\u003e\n\u003cli\u003eLikums. Administratīvo teritoriju un apdzīvoto vietu likums. 2020. https://likumi.lv/ta/id/315654. Accessed 23 June 2020.\u003c/li\u003e\n\u003cli\u003eOffice of Citizenship and Migration Affairs of Latvia. Population and population change. 2023. https://stat.gov.lv/en/statistics-themes/population/population/247-population-and-population-change. Accessed 13 Feb 2023.\u003c/li\u003e\n\u003cli\u003eChowdhury D, Krishnan A, Duggal A, Amarchand R, Hus\u0026oslash;y A, Steiner TJ. Headache prevalence and demographic associations in the Delhi and national capital region of India: estimates from a cross-sectional nationwide population-based study. J Headache Pain. 2024;25:108.\u003c/li\u003e\n\u003cli\u003eMaiga Y, Diallo SH, Sangho O, Moskatel LS, Konipo F, Bocoum A, et al. The burden of headache and a health-care needs assessment in the adult population of Mali: a cross-sectional population-based study. J Headache Pain. 2024;25:107.\u003c/li\u003e\n\u003cli\u003eKissani N, Adarmouch L, Sidibe AS, Garmane A, Founoun R, Chraa M, et al. The prevalence of headache in the adult population of Morocco: a cross-sectional population-based study. J Headache Pain. 2024;25:49.\u003c/li\u003e\n\u003cli\u003eQuispe G, Loza C, Limaco L, Gallegos R, Palomino C, Cruz I, et al. The prevalence and demographic associations of headache in the adult population of Peru: a national cross-sectional population-based study. J Headache Pain. 2024;25:48.\u003c/li\u003e\n\u003cli\u003eAdoukonou T, Agbetou M, Dettin E, Kossi O, Hus\u0026oslash;y A, Thomas H, et al. The prevalence and demographic associations of headache in the adult population of Benin: a cross-sectional population-based study. J Headache Pain. 2024;25:52.\u003c/li\u003e\n\u003cli\u003eSteiner TJ, Lipton RB, Lifting The Burden: The Global Campaign against Headache. The headache-attributed lost time (HALT) indices: measures of burden for clinical management and population-based research. J Headache Pain. 2018;19:12.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"archives-of-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aoph","sideBox":"Learn more about [Archives of Public Health](http://archpublichealth.biomedcentral.com/)","snPcode":"13690","submissionUrl":"https://submission.nature.com/new-submission/13690/3","title":"Archives of Public Health","twitterHandle":"@Archpubhealth","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"headache, epidemiology, methodology, population-based survey, cross-sectional, Latvia, global campaign against headache","lastPublishedDoi":"10.21203/rs.3.rs-7040119/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7040119/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eStudies on the prevalence and attributed burden of headache disorders of public-health importance, conducted by the Global Campaign against Headache, have so far not included data from Latvia. This paper details the adaptation and modification of the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire for the Latvian population, the methodology of its application and the challenges encountered.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe adapted the HARDSHIP questionnaire to local requirements and translated it into Latvian, the official state language, and Russian, the most widely spoken minority language. We used a population-based cross-sectional quota and stratified sampling method. Stratification variables were gender, age, nationality, type of settlement, region and highest level of education completed. Potential participants were engaged through computer-assisted random-digit dialling, followed by a telephone interview of those willing. A pilot study was conducted to assess feasibility. The main study was conducted from October 2023 to January 2024.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eTranslation challenges were few and successfully addressed. The pilot survey verified the questionnaire\u0026rsquo;s applicability. We contacted 21,436 individuals, of whom 16,371 were potential participants and 2,141 accepted the invitation and completed the interview (participation proportion: 13.1%). The gender (48.2% males, p\u0026thinsp;=\u0026thinsp;0.12), age (mean, 43.3 years, p\u0026thinsp;=\u0026thinsp;0.81), region (p\u0026thinsp;=\u0026thinsp;0.88), habitation (p\u0026thinsp;=\u0026thinsp;0.44), and nationality (p\u0026thinsp;=\u0026thinsp;0.41) distributions of the sample were statistically similar to those of the national population aged 18\u0026ndash;65. People of higher education (40.6% vs. 36.1%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were overrepresented.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThis is the first population-based survey of headache disorders in Latvia, following the recommendations on population surveys of headache disorders from the Global Campaign against Headache. The HARDSHIP questionnaire was successfully translated and adapted to local requirements. Despite a low participation proportion, the sample was highly representative of the general population regarding age, gender and habitation.\u003c/p\u003e\u003ch2\u003eTrial registration\u003c/h2\u003e\u003cp\u003eNo clinical trials performed in the study.\u003c/p\u003e","manuscriptTitle":"Methodology of a population-based survey of headache disorders among adults in Latvia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-02 02:13:40","doi":"10.21203/rs.3.rs-7040119/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-12T20:12:31+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-12T09:30:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154307527845768583759530615946568460743","date":"2025-08-25T07:00:00+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-22T08:58:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-17T08:31:33+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-17T08:28:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"Archives of Public Health","date":"2025-07-03T16:13:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"archives-of-public-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aoph","sideBox":"Learn more about [Archives of Public Health](http://archpublichealth.biomedcentral.com/)","snPcode":"13690","submissionUrl":"https://submission.nature.com/new-submission/13690/3","title":"Archives of Public Health","twitterHandle":"@Archpubhealth","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e34e07aa-38a2-4178-8804-cd16b54d2d65","owner":[],"postedDate":"September 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-22T16:01:06+00:00","versionOfRecord":{"articleIdentity":"rs-7040119","link":"https://doi.org/10.1186/s13690-025-01811-0","journal":{"identity":"archives-of-public-health","isVorOnly":false,"title":"Archives of Public Health"},"publishedOn":"2025-12-17 15:57:11","publishedOnDateReadable":"December 17th, 2025"},"versionCreatedAt":"2025-09-02 02:13:40","video":"","vorDoi":"10.1186/s13690-025-01811-0","vorDoiUrl":"https://doi.org/10.1186/s13690-025-01811-0","workflowStages":[]},"version":"v1","identity":"rs-7040119","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7040119","identity":"rs-7040119","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}