Development and Validation of a Questionnaire to Measure Quality of Life in Caregivers of Patients with Schizophrenia and Affective Disorders (SAC-QoL)

Background: Severe mental illnesses, such as schizophrenia and affective disorders, have considerable effects on the life of not only patients, but also their caregivers. Objective: The aim of this study was to develop a self-administered quality of life (QoL) questionnaire for the assessment of QoL in caregivers of patients with schizophrenia and affective disorders. Methods: Based on a mixed method approach and purposive sampling method, a sample consisting of 196 caregivers was recruited from 2 psychiatric hospitals in Tehran and Kerman, Iran, as well as a charity center in Kerman during 2015 - 16. A 67-item questionnaire was developed in the qualitative phase of the study, consisting of semi-structured interviews with 45 caregivers, comments of an expert panel, and some items from other relevant questionnaires. The item reduction in the quantitative phase was based on item distribution, missing data per item, inter-item correlation, and factor analysis. The reliability coefficient (Cronbach’s alpha) was calculated for all the dimensions. Convergent validity was assessed by Pearson’s correlation coefficient test, and discriminant validity was analyzed, using student’s t test and analysis of variance (ANOVA). Results: The final version of the questionnaire included 21 itemsand7 dimensions: emotionalburden(5 items); dealing with patient symptoms (3 items); relationship with the therapeutic team (3 items); relationship with family (2 items); financial burden (3 items); relationship with the extended family and friends (2 items); and latent worry (3 items). The 7 dimensions could explain 78.45% of the total variance. Item internal consistency was satisfactory for all the dimensions, ranging from 0.77 to 0.96 for each item. Cronbach’s alpha coefficient ranged from 0.74 to 0.89 in the whole sample. The SAC-QoL index was significantly correlated with all the dimensions of the world health organization QoL-BREF (WHOQoL-BREF) scale (r, 0.32 - 0.65). Also, the predefined hypotheses confirmed the discriminant validity (P < 0.01). Conclusions: The SAC-QoL questionnaire revealed acceptable psychometric properties. Therefore, it can be considered as a valid and reliable measure of QoL in caregivers of patients with schizophrenia and affective disorders. Moreover, it would be useful for clinicians and authorities to focus on caregivers who are primary providers of healthcare services.