Predicitive ability of NOSAS score and STOPBANG score in identifying Obstructive Sleep Apnea

Background: The increased prevalence of obstructive sleep apnea (OSA) mandates the presence of simple but accurate tools to identify patients with this disorder for early detection and prevention of serious consequences. A screening questionnaire with more of objective and less of subjective components is needed. Aims: To validate a novel score (NOSAS) in predicting OSA in Indian subcontinent. Also, this study aimed at comparing two sleep questionnaires as regards their predictive abilities for OSA. Methods: A prospective observational study included 90 patients attending OPD. Two sleep questionnaires (NOSAS and STOPBANG) were administered to the patients and scoring was done. Overnight attended Polysomnography (PSG) was done for all patients and was considered the gold standard for the diagnosis of OSA. The sensitivity, specificity, positive and negative predictive values of the two questionnaires was calculated. Results: Of 90 patients, 82(91.11%) had OSA. At AHI>5, the sensitivity, specificity, PPV, NPV, LR+, LR-, area under ROC of NOSAS score was 95%, 87.5%, 98.73%, 63.64%, 7.61, 0.06 and 0.882 while that of STOPBANG was 87.80%, 62.5%, 96%, 33%, 2.34, 0.20 and 0.816 respectively. We found substantial agreement (kappa 0.70) between NOSAS and gold standard (PSG) and a fair agreement (kappa 0.361) between STOPBANG and gold standard (PSG). However, there is only a fair agreement between NOSAS and STOPBANG (kappa 0.373). Similarly sensitivity and specificity of NOSAS score is higher than that of STOPBANG score in identifying OSA at AHI cut off values of 15, 20 and 30. Conclusion: NOSAS is a better predictor of OSA than STOPBANG questionnaire. Method: OSA, NOSAS, STOPBANG