The responsiveness of the Hamilton Depression Rating Scale

In clinical studies of antidepressants, the Hamilton Depression Rating Scal e (HAMD) total score has been the gold standard instrument for establishing and comparing the efficacy of new treatments. However, the HAMD is a multi dimensional measure, which may reduce its ability to detect differences bet ween treatments, in particular, changes in core symptoms of depression. Two mete-analyses were conducted to compare the responsiveness of the HAMD tot al score with several published unidimensional subscale scores based upon c ore symptoms of depression. The first compared the above instrument's abili ty to detect differences between fluoxetine and placebo across eight studie s involving over 1600 patients. The second analysis involved four studies a nd over 1200 patients randomized to tricyclic antidepressants and placebo. In both meta-analyses, the unidimensional core subscales outperformed the H AMD total score at detecting treatment differences. The implications of thi s on sample sizes and power for clinical studies will be discussed. In fact , studies based on the observed effect sizes from the core subscales would require approximately one-third less patients than studies based on the HAM D total score. Effect sizes from each individual HAMD item will also be pre sented to help explain the differences in responsiveness between the scales . (C) 2000 Elsevier Science Ltd. All rights reserved.