Development and initial validation of a brief mental health outcome measure

Using a combination of classical test theory and Rasch item analysis, we de veloped a short scale designed to measure the effectiveness of mental healt h treatment across a wide range of mental health services and populations. Item development for the scale was guided by literature review and intervie ws with senior clinicians and with patients. Using 3 different samples cons isting of inpatients, outpatients, and nonpatients, we reduced our initial item pool from 81 to 10 items. The 10-item scale had an alpha of .96 and sh owed strong correlations with commonly used measures of psychological well- being and distress. Our results suggest that the scale appears to measure a broad domain of psychological health. The scale appeared to lack ceiling a nd floor effects, and it discriminated between inpatients, outpatients, and nonpatients, suggesting the scale has excellent potential to be broadly re sponsive to a variety of treatment effects. In addition, the new scale prov ed to be sensitive to treatment changes in a sample of 20 psychiatric inpat ients. Overall, the initial data suggest that we have developed a brief, se nsitive outcome measure designed to have wide application across psychiatri c and psychological treatments and populations.