Spanish cross-cultural adaptation and psychometric properties of the Schizophrenia Quality of Life short-version questionnaire (SQoL18) in 3 middle-income countries: Bolivia, Chile and Peru

Objective: The aim of this study was to adapt the Schizophrenia - Quality of Life short-version questionnaire (SQoL18) for use in three middle-income countries in Latin America and to evaluate the factor structure, reliability, and external validity of this questionnaire. Methods: The SQoL18 was translated into Spanish using a well-validated forward-backward process. We evaluated the psychometric properties of the SQoL18 in a sample of 253 patients with schizophrenia attending outpatient mental health services in three Latin American countries. For participants in each country (Bolivia, N. =. 83; Chile, N. =. 85; Peru, N. =. 85), psychometric properties were compared to those reported from the reference population (507 patients with schizophrenia) assessed in the validation study. In addition, differential item functioning (DIF) analyses were performed to see whether all items behave in the same way in each country. Results: Factor analysis performed in the 3 countries showed that the questionnaire's structure adequately matched the initial structure of the SQoL18. The unidimensionality of the dimensions was preserved, and the internal/external validity indices were close to those of the reference population. However, one dimension of the SQoL18 (resilience) presented some unsatisfactory properties including low Cronbach's alpha coefficients, one INFIT value higher than 1.2, and one item showing DIF between the 3 countries. Conclusions: These results demonstrate the satisfactory acceptability and psychometric properties of the SQoL18, suggesting the relevance of this questionnaire among patients with schizophrenia in these 3 Latin American countries.