Evaluation and improvement of the psychometric properties of the Hamilton Rating Scale for Depression using Rasch analysis for applying in Belarusian population

The Hamilton Rating Scale for Depression (HAM-D) has not been tested for the psychometric properties in Belarusian population. In this regard conducting psychometric assessment of the HAM-D used in Belarusian population has special importance. The aim of this study was to investigate and improve the psychometric properties of the HAM-D applying in Belarusian population through Rasch analysis.
Data from 551 Belarusian patients with confirmed diagnosis of depression were used in this study. The Partial Credit Model was used in the psychometric analysis.
The analysis of item-person map showed disagreement between distributions of person measures and item categories. Only 8 items had appropriate values of Rasch fit-indexes. I have improved the psychometric properties of the HAM-D. Five items with bad values of fit-indexes were recombined into two new items. New items were added to the remaining 8 items with acceptable fit-indexes values and then Rasch analysis was repeated. All items showed adequate construct validity. The person separation index (PSI) for original HAM-D was 2.32. The person reliability was 0.84. Reliability analysis of the final model included 10 items showed higher estimates: the PSI was 3.61, the number of strata rose to 5.14, the person reliability was 0.93.
This study revealed that the HAM-D applied in Belarusian population has several psychometric problems. After removing invalid items and changing score rules of bipolar items psychometric properties of the scale were improved. Declaration of Interest: None.