The Calgary Sleep Apnea Quality of Life Index (SAQLI) was developed to record key elements of the disease that are important to patients. All items felt to influence the quality of life of these patients were identified. Final questionnaire items were selected by interviewing 113 patients with sleep apnea and 50 snorers who rated each item on whether it was a problem and the importance of it to their overall quality of life. Items for the final questionnaire were selected based on the rank order of the frequency ximportance product. The rank ordering was similar across strata of disease severity and between sexes. The Calgary SAQLI has 35 questions organized into four domains: daily functioning, social interactions, emotional functioning, and symptoms. A fifth domain, treatment-related symptoms, can be added for clinical intervention trials to record the possible negative impacts of treatment. The SAQLI has a high degree of internal consistency, face validity as judged by content experts and patients, and construct validity as shown by its positive correlations with the SF-36 and the improvement in scores in patients successfully completing a 4-wk trial of continuous positive airway pressure. It includes items shown to be important to patients with sleep apnea and is designed as a measure of outcome in clinical trials in sleep apnea. Flemons WW, Reimer MA. Development of a disease-specific health-related quality of life questionnaire for sleep apnea.