Background. Studies that examined community samples have reported several risk factors for the development of depressive episodes. The few studies that have been performed on primary care samples were mostly cross-sectional. Most samples had originated from highly developed industrial countries. This is the first study that prospectively investigates the risk factors of depressive episodes in an international primary care sample.

Methods. A stratified primary care sample of initially non-depressed subjects (N = 2445) from 15 centres from all over the world was examined for the presence or absence of a depressive episode (ICD-10) at the 12 month follow-up assessment. The initial measures addressed sociodemographic variables, psychological/psychiatric problems and social disability. Logistic regression analysis was carried out to determine their relationship with the development of new depressive episodes.

Results. At the 12-month follow-up, 4·4% of primary care patients met ICD-10 criteria for a depressive episode. Logistic regression analysis revealed that the recognition by the general practitioner as a psychiatric case, repeated suicidal thoughts, previous depressive episodes, the number of chronic organic diseases, poor general health, and a full or subthreshold ICD-10 disorder were related to the development of new depressive episodes.

Conclusions. Psychological/psychiatric problems were found to play the most important role in the prediction of depressive episodes while sociodemographic variables were of lower importance. Differences compared with other studies might be due to our prospective design and possibly also to our culturally different sample. Applied stratification procedures, which resulted in a sample at high risk of developing depression, might be a limitation of our study.