BMI 35 kg/m² does not fit everyone: a modified STOP-Bang questionnaire for sleep apnea screening in the Chinese population

The STOP-Bang questionnaire is the most widely used to detect surgical patients at high risk of obstructive sleep apnea (OSA). However, the body mass index (BMI) cutoff value in the original STOP-Bang questionnaire is 35 kg/m²; the BMI in the Chinese population is lower than that. We aimed to establish a more appropriate BMI cutoff value in the STOP-Bang questionnaire for Chinese patients.

A total of 790 consecutive patients scheduled to undergo surgery at our hospital were included in this prospective study. All patients were asked to complete the STOP-Bang questionnaire and undergo a 7-h overnight polysomnography (PSG). The ability of STOP-Bang questionnaire to detect moderate to severe OSA (AHI ≥ 15 events/h) was assessed.

When the BMI cutoff value was set at 28 kg/m², the questionnaire had the highest Youden index, although no significant differences were found in the sensitivity of the test compared with the original BMI cutoff in total and in male patients. In females, changing the BMI cutoff value from 35 to 28 kg/m² resulted in the sensitivity of the test significantly increasing from 79.2% (74.9–83.5) to 89.3% (84.4–94.1), while the decrease in specificity was minor (from 43.6% [41.2–46.0] to 38.2% [36.1–40.3]), and the Youden index was highest (0.27) at this cutoff value. When the STOP-Bang questionnaire score was 4, the highest Youden index was obtained.

We recommend using a BMI cutoff value (28 kg/m²), and a STOP-Bang score ≥ 4 allows the anesthetist to identify patients with high risk of OSA.