Comparing two schizophrenia-specific quality of life instruments in institutionalized people with schizophrenia

Abstract

Clinical health professionals may have difficulties to select appropriate schizophrenia-specific Quality of life (QoL) instruments because of the limited information regarding their psychometric properties. Two widely used schizophrenia-specific QoL instruments (Schizophrenia Quality of Life Scale Revision 4 [SQLS-R4] and Lancashire Quality of Life Profile [LQOLP]) were compared in institutionalized people with schizophrenia, and useful recommendations for clinical health professionals were provided. Participants (n = 100) filled out the two instruments twice. Test-retest reliability, internal consistency, and confirmatory factor analyses (CFAs) were conducted. Both SQLS-R4 domains (r = 0.573–0.731) and LQOLP domains (r = 0.303–0.778) had good test-retest reliability. However, the objective QoL domains in the LQOLP showed lower internal consistency (α = 0.219–0.617) than its subjective QoL domains (α = 0.532–0.947) and the SQLS-R4 domains (α = 0.768–0.939). The CFAs with two correlated underlying instruments constructs and two correlated underlying QoL traits (viz., Physical and Psychosocial QoL) performed the best data-model fit (CFI = 0.990, RMSEA = 0.039, SRMR = 0.039), which supported the validity of both instruments. Although both SQLS-R4 and LQOLP were valid and reliable, using SQLS-R4 on institutionalized people seemed to be more psychometrically solid than using the LQOLP.