Analysis of Classes Used in the Treatment of Depression by Physician-reported Severity.

We analyzed use of therapeutic drug classes for the treatment of depression by the three levels of physician-reported disease severity (mild, moderate, and severe) to understand if the mix of therapeutic classes used to treat depression changes as disease severity increases. Prior to analyzing drug uses in each severity category, we established that in the 12 months ending November 2009, the majority of patients (65%) were assigned a severity rating of 'moderate' by their physician; 27 percent and eight percent of patients were designated as 'mild' and 'severe,' respectively. In general, we found that as disease severity changes, so too do the proportions of the various therapeutic classes used in depression. The differences in class mix by severity have persisted at least since the 12 months ending December 2008, and it appears that the mix of drug classes used in severe depression are becoming less similar to the class mix for moderate depression over time.