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

Studies 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. 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. 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 (participating 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 years. People of higher education (40.6% vs. 36.1%, p < 0.001) were overrepresented. 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 participating proportion, the sample was highly representative of the general population regarding age, gender and habitation.