moderate or severe type at their second psychiatric treatment contact, 3.1% a diagnosis of persistent mood disorders or recurrent depression, currently in remission, 0.7% a diagnosis of bipolar disorder, and 17.2% had a non-affective diagnosis at their second psychiatric contact. The 8767 patients with a diagnosis of recurrent depressive disorder, current episode mild, moderate or severe type, were selected for further analyses. The same procedure was undertaken at subsequent episode contacts (3 -- 15) (i.e. at every contact selecting only patients with recurrent depressive disorder for further analyses). Table DS1 presents the prevalence of mild, moderate and severe depressive episodes as well as the prevalence of severe depressive episodes with psychotic symptoms at hospital contact (from 1 to 15) -- as a total and according to gender. The prevalence of severe depressive episodes increased from 25.5% at the first contact to 50.0% at the 15th. Similarly, the prevalence of severe depressive episodes with psychotic symptoms increased from 8.7% at the first hospital contact to 25.1% at the 15th (Table DS1 and Fig. 1 ). In contrast, the prevalence of mild and moderate depressive episodes decreased during the course of the illness. The association between the episode number and the prevalence of severe depressive episodes could be a result of a selection bias, as patients with many episodes may have an increased prevalence of severe episodes from the beginning of their illness which could further dominate the analyses with regard to the number of episodes. Thus, in additional analyses, the association