A critical examination of the sensitivity of unidimensional subscales derived from the Hamilton Depression Rating Scale to antidepressant drug effects

Abstract

Unidimensional subscales for assessment of major depression may be more sensitive to antidepressant drug effects than the Hamilton Depression Rating Scale (HAM-D). To further examine this possibility, we analyzed pooled data from eight comparable, well-controlled clinical trials of venlafaxine and compared such subscales and the 17-item HAM-D (HAM-D(17)) based on effect size and number of patients required for 80% power. Symptoms of depression were assessed using the HAM-D among intent-to-treat patients (2045) randomly assigned to receive venlafaxine (immediate release, n = 474; extended release, n = 377), one of several selective serotonin reuptake inhibitors (SSRIs) (n = 748), or placebo (n = 446) for up to 8 weeks. With SSRIs or venlafaxine vs. placebo, subscales yielded effect sizes (0.328-0.528) 16 to 76% larger than the HAM-D(17) did (0.237 and 0.396, respectively), and required 31 to 64% fewer patients for 80% power. With venlafaxine vs. SSRIs, the subscales showed no advantage over the HAM-D(17); all devices yielded comparable, positive effect sizes (0.183-0.195). Final subscale scores significantly predicted (all P < 0.05) whether patients met criteria for remission (eg, HAM-D(17) score of < or = 7). These findings suggest that unidimensional subscales are more sensitive to antidepressant drug effects than the HAM-D(17) is, but only in active agent/placebo comparisons. Our data further suggest the subscales can predict the presence of remission. Given these findings, prudent use of these subscales may be appropriate, cost-effective, and informative.