ABSTRACT
Objective: In a cross-sectional study regarding long-term sickness absence to estimate: 1) The prevalence of mental disorders among incident individuals on long-term sickness absence; 2) The diagnostic frequencies in total and divided by participants and non-participants; and 3) Divided by socio-demographic characteristics. Method: In a well-defined cohort with complete coverage, 2414 individuals entering LSA during one year were identified. In a two-phase study, the 1121 (46.4%) participants constituted Phase 1 and they were screened for mental disorders by Common Mental Disorders—Screening Questionnaire. In Phase 2, a subgroup of Phase 1, 337 individuals were diagnosed by means of Present State Examination. Compensation for non-participation was carried out by multiple imputation by the use of data known for all sick-listed individuals from public registers. Results: The frequencies of mental disorders were: Any mental disorder 52%, depression 36%, anxiety 15%, somatoform disorder 7%, alcohol and drug dependence 6%, and personality disorder 6%. The diagnostic frequencies were highest for non-participants, female gender, age below 40 years, urban areas, single status, higher education, high skills/ managers, without a job, and low income. Conclusion: The prevalence of mental disorders among incident individuals on LSA was found to be about 50%. The burden on society may be higher than expected from previous studies solely based on participants as the methods compensating for missing values in this study indicated that the frequency of mental disorders was higher among non-participants than among participants.