The prognosis of minor depression in the general population: a systematic review.

Minor depression is common in the general population. There is no consensus about prognostic indicators that can identify people at high and low risk of chronicity. We systematically reviewed the available literature on the prognosis of minor depression in the general population and identified five studies. Two of these were considered to be of relatively high methodological quality. There was a wide variety among the studies in the definitions of minor depression, the characteristics of the study population, length of follow-up and type of outcome measure. The results show that the majority of people with minor depression have a favorable prognosis; 46-71.4% achieve remission after a follow-up of 1-6 years. However, 16-62.3% still have a minor depression after 5 months to 1 year of follow-up, suggesting that for many people minor depression is chronic or recurrent; 12.7-27% develop a more severe form of depression; they were diagnosed with dysthymia or major depression after 1-6 years of follow-up. There was inconsistent evidence regarding mortality and functional impairment. No study presented results of prognostic factors, so it remains unclear which people have a more favorable course than others. The results of our review need to be interpreted with caution because of the small number of studies and the large heterogeneity among studies.