Study approach and field work procedures of the MentDis_ICF65+ project on the prevalence of mental disorders in the older adult European population

Background This study describes the study approach and field procedures of the MentDis_ICF65+ study, which aims to assess the prevalence of mental disorders in older adults. Methods An age-appropriate version of the Composite International Diagnostic Interview (CIDI65+) was developed and tested with regard to its feasibility and psychometric properties in a pre-test and pilot phase. In the cross-sectional survey an age-stratified, random sample of older adults (65–84 years) living in selected catchment areas of five European countries and Israel was recruited. Results N = 3142 participants (mean age 73.7 years, 50.7% female) took part in face-to-face interviews. The mean response rate was 20% and varied significantly between centres, age and gender groups. Sociodemographic differences between the study centres appeared for the place of birth, number of grandchildren, close significants, retirement and self-rated financial situation. The comparison of the MentDis_ICF65+ sample with the catchment area and country population of the study centres revealed significant differences, although most of these were numerically small. Conclusions The study will generate new information on the prevalence of common mental disorders among older adults across Europe using an age-appropriate, standardized diagnostic instrument and a harmonized approach to sampling. Generalizability of the findings and a potentially limited representativeness are discussed