Objective:To evaluate the value of improved Mallampati grading combined with 
NoSAS questionnaire in screening for obstructive sleep apnea （OSA）. Method:A 
total of 344 patients admitted to our hospital for sleep disorders were studied. 
All patients were measured for their height, weight, neck circumference and 
other parameters. NoSAS scores, improved Mallampati grading and polysomnography 
（PSG） were performed in these patients. According to AHI in PSG monitoring 
results, patients were divided into non-osa group （AHI<5） 93 cases and OSA group 
251 cases. The OSA group were divided into mild （AHI 5-15）, moderate（AHI 16-30） 
and severe OSA group（AHI>30） according to the PSG result. The ROC curve was 
plotted to evaluate the screening value of NoSAS and improved Mallampati grading 
combined with NoSAS for OSA. Result:With the NoSAS score of 8 or 9 as cutoffs 
for analysis, the sensitivity for OSA was 0.733 and 0.701; the specificity for 
OSA was 0.538 and 0.624, respectively. The sensitivity and specificity of NoSAS 
combined with improved Mallampati grading for screening OSA were 0.813 and 
0.710, respectively. Conclusion:As a new screening tool, NoSAS questionnaire is 
simple and convenient, and has certain screening value to OSA. The improved 
Mallampati grading combined with NoSAS questionnaire can obviously improve the 
screening sensitivity and specificity of Osa, and has higher application value.