Chronic pain and major depressive disorder in the general population.

This study aims (1) to assess the prevalence of Chronic Painful Physical Condition (CPPC) and major depressive disorder (MDD) in the general population; (2) to evaluate their interaction and co-morbidity with sleep and organic disorders; and (3) to investigate their daily functioning and socio-professional consequences. A random sample of 3243 subjects (18years), representative of California inhabitants, was interviewed by telephone. CPPC duration was at least 6months. Frequency, severity, duration and consequences on daily functioning, consultations, sick leave and treatment were investigated. MDD were assessed using DSM-IV criteria. The point prevalence of CPPC was 49% (95% confidence interval: 47.0-51.0%). Back area pain was the most frequent; 1-month prevalence of MDD was at 6.3% (95% CI: 5.5-7.2%); 66.3% of MDD subjects reported at least one CPPC. In 57.1% of cases, pain appeared before MDD. Pain severity was increased by poor sleep, stress and tiredness in MDD subjects. Being confined to bed, taking sick leave and interference of pain with daily functioning were twice as frequent among MDD subjects with CPPC than in non-MDD subjects with CPPC; obese individuals with CP were 2.6 times as likely to have MDD. Pain is highly linked with depressive disorder. It deteriorates physical, occupational and socio-professional activities. Pain and sleep disturbances are a prime motive of consultation rather than depressed mood, underlining the risk of missing a depression diagnosis.