Background: Examining predictors of the outcomes of major depressive disorder (MDD) is important for clinical practice and population health. There are few population-based longitudinal studies on this topic. The objectives of this study were to (1) estimate the proportions of persistent and recurrent MDD among those with MDD over 1 year, and (2) identify demographic, socio-economic, workplace psychosocial and clinical factors associated with the outcomes.
Method: From a population-based longitudinal study of the working population, participants with a lifetime diagnosis of MDD were selected (n=834). They were classified into two groups: those with and those without current MDD. The proportions of 1-year persistence and recurrence of MDD were estimated. MDD was assessed by the World Health Organization (WHO) Composite International Diagnostic Interview, CIDI-Auto 2.1, by telephone.
Results: The proportions of persistent and recurrent MDD in 1 year were 38.5% [95% confidence interval (CI) 31.1-46.5] and 13.3% (95% CI 10.2-17.1) respectively. Long working hours, negative thinking and having co-morbid social phobia were predictive of persistence of MDD. Perceived work-family conflict, the severity of a major depressive episode and symptoms of depressed mood were significantly associated with the recurrence of MDD.
Conclusions: Clinical and psychosocial factors are important in the prognosis of MDD. The factors associated with persistence and recurrence of MDD may be different. More large longitudinal studies on this topic are needed so that clinicians may predict potential outcomes based on the clinical profile and provide interventions accordingly. They may also take clinical action to change relevant psychosocial factors to minimize the chance of persistence and/or recurrence of MDD.