Studies that assessed the diagnostic value of questionnaires, clinical scales or prediction equations compared with standard overnight polysomnography in a hospital or laboratory facility for diagnosis of obstructive sleep apnoea were eligible for inclusion. Studies were required to report pretest probabilities and data to enable construction of a 2x2 table, sensitivity and specificity or positive and negative likelihood ratios.
A number of questionnaires and clinical models were assessed. These included Berlin questionnaire, Sleep Disorders Questionnaire, checklist of the American Society of Anesthesiologists, Snoring Questionnaire, Kushida Index and Epworth Sleepiness Scale. A range of apnoea-hypopnoea index thresholds were used (between 5 and 10 for apnoea and 25 or 30 for severe apnoea).The prevalence of obstructive sleep apnoea ranged from 9% to 85%. The proportion of men in the included studies ranged from 24% to 100%.
Two reviewers independently assessed the studies for inclusion in the review; disagreements were resolved through discussion and consultation with a third reviewer.