Objective: Obstructive sleep apnea syndrome is a prevalent sleep disorder involving various domains of quality of life that require an objective evaluation. The aim of the present study was to validate a specific measure of health related quality of life in Portuguese sleep apnea patients----the SAQLI. Materials and methods: A sample of 206 Portuguese sleep apnea patients completed a Portuguese version of SAQLI for assessment of its comprehensibility, construct validity and reliability and

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... ted the same measures after 1---3 months CPAP therapy. Hospital Anxiety and Depression Scale (HADS) was also used to test construct validity. Results: Cronbach alpha coefficients of internal validity were above the standard (0.70) in all domains. Factor analysis showed that the items of daily functioning, emotional and symptoms domains all loaded on the hypothesized scales. Longitudinal data showed a significant difference (p < 0.001) in each SAQLI domain and between total score before and after CPAP use. In terms of external validity, all SAQLI domains were negatively correlated with anxiety and depression scales. Conclusions: Overall the results of the present study demonstrated that the Portuguese version of SAQLI to be psychometrically valid and applicable for evaluate the impact of sleep apnea and CPAP treatment in Portuguese patients.