NoSAS score diagnostic accuracy for obstructive sleep apnea screeningNoSAS score shows mixed accuracy for screening obstructive sleep apnea across severity levels

Obstructive sleep apnea (OSA) is a prevalent yet underdiagnosed condition. Although the Neck Circumference, Obesity, Snoring, Age, and Sex (NoSAS) score is commonly used in clinical practice. This study aimed to evaluate the performance of the NoSAS score in detecting mild, moderate, and severe OSA, based on the apnea-hypopnea index (AHI) or respiratory event index (REI). PubMed, Embase, ProQuest Dissertations and Theses A&I, Ovid Medline, CINAHL Plus, and Web of Science were searched for relevant articles published before August 29, 2025. We included studies evaluating the sensitivity and specificity of the NoSAS score compared with polysomnography or other validated references. A bivariate random-effects model was used for data analysis. Our meta-analysis included 31 studies, 25 on mild or AHI/REI ≥5 events/h, 31 on moderate or AHI/REI ≥15 events/h, and 24 on severe or AHI/REI ≥30 events/h. The pooled sensitivity and specificity were 71% and 66% for mild OSA, 73% and 62% for moderate OSA, and 82% and 50% for severe OSA, respectively. Moderator analysis revealed an association between BMI and higher sensitivity for mild and severe OSA. Larger sample sizes were associated with higher specificity for mild OSA. Advanced age was associated with pooled specificity in severe OSA. Caucasian countries increased sensitivity in all OSA severity and increased specificity in severe OSA compared to Asian countries. Sleep-related clinic has higher specificity in both of moderate and severe OSA and increased sensitivity in moderate OSA (all p < 0.05) compared to community-based settings. We suggest that the NoSAS score performed consistently across OSA severities, making it useful in resource-limited settings. Nevertheless, our findings should be interpreted with caution due to the high degree of heterogeneity.