Heterogeneity among depressed outpatients considered to be in remission

More than a decade ago, a consensus panel recommended that remission be defined on the 17-item version of the Hamilton Rating Scale for Depression (HAM-D) as a cutoff of less than 7. Recently, some investigators have suggested that this threshold to define remission may be too high. If true, this means that heterogeneity exists within the group of treatment remitters accounting for variance in psychosocial function and relapse risk. In the present report from the Rhode Island Methods to Improve Diagnostic Assessment and Services project, we examined whether there is heterogeneity within the group of patients that are typically classified as remitters. Three hundred three depressed psychiatric outpatients were rated on the Standardized Clinical Outcome Rating for Depression, an index of Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition remission status, and the 17-item HAM-D. Approximately half of the patients completed a measure of psychosocial impairment. Treatment responders were divided into 2 groups, remitters (HAM-D < or =7) and nonremitters (HAM-D > or =8). The treatment remitters were further subdivided into 2 groups, remitters with and without mild residual symptoms (HAM-D 3-7 vs 0-2). We refer to these 3 nonoverlapping groups as responders, partial remitters (ie, remitters with mild residual symptoms), and full remitters (remitters without residual symptoms). Responders scored statistically significantly higher, indicating greater psychosocial impairment, than the entire group of remitters, and the partial remitters scored significantly higher than the full remitters. Among the responders, the correlation between remission status and functioning was -.49 (P < .01). Among the remitters, the correlation between residual symptom status and functioning was nearly as high (-.42, P < .05). These results suggest that there is as much heterogeneity among patients who are typically considered to be in remission as there is among responders. This supports recommendations to lower the cutoff on the HAM-D to define remission.