Validation of a new scale to assess quality of life in schizophrenic patients treated with antipsychotic drugs, the RSM-scale

The assessment of quality of life has become more important in clinical studies as a new outcome parameter in schizophrenia. Current used scales were not developed to measure quality of life in treated schizophrenic patients with regard to the efficacy and side effect profile of atypical antipsychotics. We developed a new scale – the RSM-scale – with an interviewer and a self-rating part. We defined a priori subscores and performed a factor analysis. The primary objective of this study was to evaluate this new scale in terms of validity and reliability. Inclusion criteria were a diagnosis of schizophrenia and a current inadequate response to treatment or side effects. As reference scales we used the Qualtiy of Life and the SWN-K scale. Psychopathology was measured using the PANSS, CGI and GAF scales. Side effect profiles were measured using the ESRS and UKU-scale. The study plan encompassed four visits over eight weeks. All together 145 patients participated in the study. Tests for reliability revealed a Cronbach's value of 0.915 for the self-rating part and of 0.913 for the interviewer rating part. The RSM scale reached adequate results for test-retest stability, discriminant validity, construct validity and scale score distribution. The overall correlation between both scales in all patients was mild to moderate, so the performance of a self-rating in addition to an interviewer rating makes sense to gain subjective information about quality of life in schizophrenic patients.