Diagnosing major depressive disorder IV: relationship between number of symptoms and the diagnosis of disorder.

The symptom inclusion criteria for DSM-IV major depressive disorder (MDD) consist of a list of nine characteristic features of depression, at least five of which must be present. Two of the criteria for MDD, low mood and loss of interest or pleasure, are accorded greater importance than the remaining seven criteria in that one of these two features is required for the diagnosis. The implicit assumption underlying this organization of the criteria is that some individuals might meet five of the nine criteria without experiencing low mood or loss of interest or pleasure and thus be inappropriately diagnosed with major depression. We are not aware of any studies that have examined this assumption. In the present report from the Rhode Island Methods to Improve Diagnostic Assessment and Services project, we examined how many psychiatric outpatients meet five of the nine DSM-IV criteria for MDD without simultaneously experiencing either low mood or loss of interest or pleasure. If this pattern is rare or does not exist, then the method of counting criteria to diagnose major depression could be simplified to a straightforward five out of nine. Twenty-seven (1.5%) patients reported five or more criteria in the absence of low mood or loss of interest or pleasure. More than half (N = 16) of these 27 patients were diagnosed with MDD or bipolar disorder, depressed type, in partial remission (N = 14), bipolar disorder mixed type (N = 1), or bipolar disorder not otherwise specified (N = 1). Six of the remaining 11 patients were diagnosed with depressive disorder not otherwise specified. Thus, few patients who met five or more of the MDD criteria were not diagnosed with a depressive disorder. This suggests that the diagnostic criteria for MDD can be simplified to a straightforward symptom count without reference to the necessity of low mood or loss of interest or pleasure.