Translating the HAM-D into the MADRS and vice versa with equipercentile linking

Background: The Hamilton Depression Rating Scale (HAM-D) and the Montgomery Asberg Depression Rating Scale (MADRS) are scales used frequently to rate the symptoms of depression. There are many situations in which it is important to know what a given total score or a percent reduction from baseline score of one scale means in relation to the other scale. Method: We used the equipercentile linking method to identify corresponding scores of simultaneous HAM-D and MADRS ratings in 4388 patients from 31 mirtazapine trials in major depressive disorder. Data were collected at baseline and at weeks 1, 2 and 4. Results: HAM-D scores of 10, 20, 30 and 40 roughly corresponded to MADRS scores of 13, 26, 39 and 52-53, respectively. An absolute HAM-D improvement of 10, 20, 25 points corresponded to a MADRS improvement of 12, 26, and 34. A percentage improvement from baseline of the HAM-D was approximately the same as a percentage improvement on the MADRS. Conclusion: These results are important for the comparison of trials that used the HAM-D and MADRS. We present conversion tables for future research.