Validation of the NoSAS score for the screening of sleep-disordered breathing: a retrospective study in Egypt

Background This study was carried out to validate the NoSAS score and assess its performance in predicting clinically significant sleep-disordered breathing (SDB) in patients referred for a sleep study and to compare its performance with the recent (No-Apnea score) and the STOP-BANG questionnaire. Patients and methods This is a retrospective study of an existing database of consecutive outpatients who were referred for suspected SDB at the sleep lab of Chest Department in Alexandria Main University Hospital from October 2012 to December 2018. We enrolled patients of at least 18 years who completed a full-night polysomnography. We defined clinically significant SDB as an apnea–hypopnea index (AHI) of at least 20 events/h. We assessed the validity of the NoSAS score and compared its performance with the No-Apnea score and the STOP-BANG questionnaire. Results After the exclusion of patients who did not fulfill our inclusion criteria, 362 out of 720 patients were enrolled. Only 5% were not diagnosed with SDB (AHI<5). Moderate-severe SDB was present in 82.4% of patients. Using a threshold of at least 8 at different AHI cut-offs (5, 10, 15, 20, 25, 30), the NoSAS score showed area under the curve (AUC) similar to the STOP-BANG Questionnaire only at AHI of at least 20 (AUC 0.77), whereas at the other AHI cut-offs (5, 10, 25, 30), the STOP-BANG Questionnaire showed higher AUC. At all AHI cut-offs, the NoSAS score was superior to the No-Apnea score. Conclusion Despite its simplicity, the NoSAS score is a valuable screening tool, especially when resources are limited.