Psychometric validations and comparisons of schizophrenia-specific health-related quality of life measures

To compare schizophrenia-specific quality of life measures, this study examined an 18-item Chinese version of 41-item Quality of Life Questionnaire in Schizophrenia (S-QoL; S-QoL-18-C) using 41 patients. The S-QoL-18-C was validated and compared with Schizophrenia Quality of Life Scale-Revision 4 (SQLS-R4). Index scores of S-QoL-18-C showed nearly identical psychometrics to S-QoL-C and S-QoL-18. No significant ceiling/floor effects were found, except with psychological and selfesteem subscales. Internal consistency was acceptable for whole scale and all subscales, except family relationships and sentimental life. Test-retest reliability was moderate to high (ICC=0.58-87). Score distributions and reliability of S-QoL-18-C were slightly lower than those of S-QoL-C. Convergent validity was supported by satisfactory correlations between subscales/index scores of S-QoL-18-C and similar scales (r=∣-0.35 ∣ to 0.80) and between corresponding subscales in S-QoL-18-C and S-QoL-C (r=0.85-0.97). S-QoL-18-C and SQLS-R4 demonstrated discriminant validity by differentiating among 30 patients with symptom remission, 30 patients without symptom remission, and 30 healthy individuals. Two patient groups were classified by criteria proposed by Remission in Schizophrenia Working Group. Three groups were controlled for five factors. Furthermore SQLS-R4, but not S-QoL-18-C, differentiated between patient groups with different hospitalization frequencies. Overall, S-QoL-18-C and SQLS-R4 show different advantages psychometrically.