Independent validation of the Sleep Apnoea Quality of Life Index.

Abstract

Obstructive sleep apnoea (OSA) affects important domains of quality of life which remain unexplored by conventional sleep recordings. The objective of this study was to examine the measurement properties (both discriminative and evaluative) of the Sleep Apnoea Quality of Life Index (SAQLI), a new OSA specific quality of life questionnaire. Consecutive patients recently diagnosed with OSA completed a French version of the SAQLI twice over a 3 month period. Its construct validity and responsiveness were tested by comparing baseline and change scores obtained in each domain (symptoms, activities, emotions, social interactions) with those of questionnaires measuring related constructs (SF-36, Epworth Scale, Beck Depression Inventory, and Symptom Checklist 90). The symptoms scores were also correlated with physiological measures obtained at baseline polysomnographic recording. Forty seven patients (40 men) of mean (SD) age 53 (10) years and mean (SD) apnoea/hypopnoea index 38 (21) participated in the study. During the study period 33 of the 47 patients were treated for OSA (31 with nasal CPAP, one with uvulopalatopharyngoplasty, and one with an oral appliance). Moderate to high correlations were found between the scores in each domain of the SAQLI and the corresponding instruments. There were significant differences in change scores between patients who were treated and those who were not, moderate correlations between SAQLI change scores and changes in the corresponding instruments, and no correlation between the symptoms scores and the baseline nocturnal features. Most of these correlations met the a priori predictions made regarding their magnitude. The SAQLI has strong construct validity and is responsive to change in quality of life but has the disadvantage of having to be administered by an interviewer.