OBJECTIVES: The NoSAS score has been shown to be a reliable screening tool for 
obstructive sleep apnea (OSA) in overall populations. This study aimed to 
explore the effects of age and sex on the predicting performance of this score.
METHODS: A retrospective analysis was conducted on 1119 subjects aged ≥ 18 years 
and with a total sleep time of ≥ 4 h during overnight polysomnography. 
Discrimination was assessed by using areas under receiver operating 
characteristic curve (AUCs), while predictive parameters were calculated by 
using contingency tables.
RESULTS: Overall, a NoSAS score of 8 points or higher resulted in sensitivity, 
specificity, and AUC for predicting an apnea-hypopnea index (AHI) of ≥ 20 
events/h of 74%, 36%, and 0.63 (in non-elderly 73%, 46%, and 0.65; in elderly 
91%, 17%, and 0.59; in men 85%, 18%, and 0.56; in women 52%, 76%, and 0.71, 
respectively). The AUCs at all AHI cutoffs were significantly lower in men than 
in women (all with p < 0.01), while the AUCs at AHI cutoff of 5, 15, and 30 
events/h were significantly lower in elderly than in non-elderly (p < 0.01, 
0.05, and 0.05, respectively). In non-elderly, a conventional NoSAS with cutoff 
of 7 or a modified NoSAS with age cutoff of 50 years provided sensitivity and 
specificity for predicting an AHI of ≥ 20 events/h of 87%, 37% and 80%, 36%, 
respectively, with comparable AUCs. In women, a conventional NoSAS with cutoff 
of 6 or a modified NoSAS with neck circumference cutoff of 35 cm provided 
sensitivity and specificity for predicting an AHI of ≥ 20 events/h of 85%, 39% 
and 79%, 52%, respectively, with comparable AUCs.
CONCLUSIONS: NoSAS score has better discrimination but lower sensitivity for 
predicting OSA in non-elderly and women than in their counterparts. Age- and 
sex-specific cutoff values reverse this imbalance. Our results underline the 
preference of age- and sex-specific cutoff values and the need for better age- 
and sex-specific screening algorithms.