Validation of a questionnaire instrument for prediction of obstructive sleep apnea in Hong Kong Chinese children.

To develop and validate a questionnaire scale that can be used as a screening tool to investigate for the presence of childhood obstructive sleep apnea syndrome (OSAS) in Hong Kong Chinese children. Subjects suspected to have OSAS and controls were recruited. Parents completed a Hong Kong children sleep questionnaire (HK-CSQ) and all recruited subjects underwent at least one overnight polysomnographic study (PSG). An obstructive apnea index (OAI) >or= 1/h was diagnostic of OSAS. Receiver-operating characteristics (ROC) curve was constructed to determine optimal sensitivity and specificity. Reliability and validity of the questionnaire scale were also assessed. Two hundred twenty-nine children (149 boys and 80 girls) with a mean age of 10.0 years (SD = 2.1) were recruited. Their mean body mass index (BMI) and OAI were 19.8 (SD = 5.1) and 2.6 (SD = 7.6), respectively. Fifty-four boys and 12 girls were found to have OSAS. Three questions were found to be highly significant in predicting for the presence of OSAS-snoring, nocturnal mouth breathing, and sweating. A composite score of 7 from the three questions (range 0-12) was found to discriminate the OSAS cases best [ROC curve, AUC = 0.8 (95% CI = 0.8-0.9)]. The sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were 75.4, 80.5, 61.3, and 88.9%, respectively. Test-retest reliability was undertaken in 51 subjects and the measurement of agreement (Kappa value) was 0.6. This HK-CSQ is a useful, valid, and reliable screening instrument for the presence of OSAS in children.