Course of treatment received by depressed patients

Using data from an observational study of affective disorders, we describe the rates of transition among levels of antidepressant treatment for subjects with Major Depressive Disorder (MDD), and relate these changes to changes in clinical status. We report on the treatment received during the first 10 years of follow-up in the Collaborative Depression Study by 555 patients with a diagnosis of MDD of at least one month's duration. This work extends the initial examination of treatment received during the first eight weeks after entry into this study that showed depressed patients to be on low levels of treatment. Multiplicative intensity models which generalize survival analysis models were used to analyse these data. Description of the course of treatment of these depressed patients shows that low levels of treatment persist for these patients across subsequent episodes, and that these episodes, like the index one, are characterized by extended time in a symptomatic subcriterion state after acute symptoms have improved. These long-term descriptions of treatment support the initial hypothesis that these CDS patients were undertreated. The long-term tendency toward undertreatment seems to persist even as newer treatments become available and widely accepted in practice.