Body weight and obstructive sleep apnea: a mathematical relationship between body mass index and apnea-hypopnea index in veterans.

STUDY OBJECTIVES

A high body mass index (BMI) is a risk factor for obstructive sleep apnea. However, to our knowledge there is no reported equation that quantifies the relationship between weight, as measured by BMI, and apnea severity, as assessed by the apnea-hypopnea index (AHI). Our objective was to find a mathematical relationship between BMI and AHI.

METHODS

We prospectively recruited 434 veterans from our polysomnography laboratory. Veterans already undergoing a sleep study were approached, and those who consented were enrolled. The veterans who enrolled in our study also participated in their scheduled sleep study. This study was approved by our institutional review board.

RESULTS

We found a simple mathematical relationship between BMI and AHI: for every 1-point drop in BMI (corresponding to 5-8 pounds, depending on a person's height), AHI decreases by 6.2%. And limiting BMI to 25-40 kg/m (which includes about 80% of the BMIs), then AHI drops by 7.1%. Simply put as a rule of thumb: For every 7-pounds drop in weight, expect a 7% drop in AHI.

CONCLUSIONS

To our knowledge, this is the first simple mathematical equation that associates the severity of weight with the severity of apnea in veterans. This equation can be a practical rule of thumb that can be implemented in clinics to predict the amount of weight a patient needs to lose to decrease their apnea, which might help motivate patients to lose weight.

CITATION

Fattal D, Hester S, Wendt L. Body weight and obstructive sleep apnea: a mathematical relationship between body mass index and apnea-hypopnea index in veterans. . 2022;18(12):2723-2729.