Medical disorders affect health outcome and general functioning depending on comorbid major depression in the general...

The objective of this study was to compare health-related quality of life (HR-QoL), disability/work productivity, and health care utilization in a variety of medical disorders with and without comorbid major depressive disorder (MDD) in the general population.

Twelve-month MDD (Composite International Diagnostic Interview) diagnosis was determined among 4181 participants from a community sample. Medical diagnoses (respiratory, cardiovascular, allergic, endocrine/metabolic, gastrointestinal, and neurological diseases) were made after medical examination. HR-QoL was evaluated with the MOS-SF-36. Outpatient doctor visits and disability/work productivity were assessed by self-report.

Comorbid MDD was associated with a lower SF-36 mental summary score in all medical diagnoses and with a lower physical summary score in comorbid allergic and neurological disorders. The number of coexisting medical disorders was strongly related to lower physical and mental summary scores in cases without comorbid depression. The number of outpatient doctor visits increased by 42% when any of the medical disorders without comorbid MDD was present, and comorbid MDD was associated with a further 24-42% increase, depending on the medical disorder. Comorbid MDD was strongly associated with lower full-time working status (37.1% with MDD vs. 51.0% without MDD) and with a significant increase in disability days (45%) in the presence of any medical disorder.

Findings have consequences for diagnostic and treatment procedures, as well as in relation to the importance of the number of medical disorders in future studies.