Prevalence, comorbidity, onset, severity and treatment of mental disorders among long-term sick-listed workers

Objectives To assess prevalence, comorbidity, onset, severity and treatment of mental disorders in a population of sick listed workers. Methods In a cross-sectional design, data were collected from a sample of 346 long term sick listed Dutch workers in 2008-9. Respondents were interviewed using the Composite International Diagnostic Interview 3.0 (CIDI) generating lifetime, 12-month and 30-day DSM-IV mental disorder. Interview data were linked to administrative data on mental health and demographics. Results Prevalence of any lifetime, 12-month and 30-day DSM-IV mental disorder is very high (mood disorder: 50.6%, 28.6%, 9.5%; anxiety disorder: 53.2%, 32.9%, 20.2%; substance use disorder 22.0%, 4.6%, 2.3%). All mental disorders have early ages of onset. Comorbidity of DSM-IV mental disorder is substantial (58.1% ≥1 lifetime; 33.7% ≥1 12-month; 15.8% has ≥1 30-day). Urogenital and gastrointestinal diseases, and neoplasms, coincide with 12-month mental disorder in 66.7%, 53.9% and 51.7% of cases. More than 2/3 of specific mental disorders are serious in terms of impairment and disability. Substantial numbers of respondents with 12-month DSM-IV mental disorder seek treatment with great delay or have no treatment at all (social phobia: 65.6%; major depression: 30.1%; general anxiety disorder: 25.0%). Conclusions The results have implications for professionals in primary, occupational and insurance healthcare assessing disability due to poor mental health. Indications are found that mental disorders among long-term sick-listed workers are substantially underdiagnosed. More research is needed to identify determinants of undiagnosed and untreated mental disorders among long-term sick-listed workers.