Clinical predictors of obstructive sleep apnea

Abstract

Objective: To identify physical findings that can be standardized to predict the presence and the severity of obstructive sleep apnea (OSA).

Study design: One hundred seventy-two patients who answered questionnaires with responses that suggested they might have OSA were included in this prospective study.

Methods: All patients underwent a physical examination and polysomnography. The physical examination included the measurement of four parameters used by anesthesiologists to identify patients likely to have difficult intubation to determine if these same parameters predict OSA. We recorded modified Mallampati grade (MMP), tonsil size, and body mass index (BMI) and measured thyroid-mental distance (TMD) and hyoid-mental distance (HMD) in the study population.

Results: When the physical findings were correlated singly with the respiratory disturbance index (RDI), we found that MMP (P < .001), tonsil size grading (P = .008), and BMI (P = .003) were reliable predictors of OSA. A greater correlation with OSA emerged when an "OSA score" was formulated by factoring the MMP, tonsil grade, and BMI grade (RDI = 7.816 x MMP + 3.988 x Tonsil Size + 4.675 x BMI - 7.544). A high score was not only predictive of OSA but also correlated well with OSA severity. Neither HMD nor TMD correlated with the severity of RDI.

Conclusions: An OSA score may help identify those patients who should have a full sleep evaluation.