Neck anthropometry and the prediction of sleep apnea in adult females

This observational laboratory study was designed to evaluate neck size and subdermal neck fat as predictors of obstructive sleep apnea syndrome (OSAS) in adult females. Forty (n = 40) female patients referred to the sleep lab for apnea screening were evaluated for body mass index (BMI), neck circumference, predicted percent of neck circumference (PPNC), submental skinfold thickness, neck skinfold thickness, situational sleepiness (Epworth Sleepiness Scale), and self-rated abnormal sleep breathing behavior. Subjects received a standard all-night clinical polysomnogram. Scored sleep studies were interpreted and obstructive apnea diagnosis severity codes were assigned based on respiratory disturbance index (RDI). Data were also collected on a non-random, non-sleeper sample of adult females (n = 40) for comparison to the sleeper group. It was hypothesized that neck circumference, submental skin-fold, and Epworth Sleepiness Scale Score would be predictor variables for RDI and could improve previously published multiple regression models. Confidence intervals were set at 0.95, and level of significance at p $\le$ 0.05 for all tests. Forward selection stepwise regression analysis showed that neck circumference and composite self-rated sleep breathing behavior score were the only significant predictor variables for RDI (CI 0.95, r$\sp2$ = 0.2979, p $\u3c$ 0.01). The Epworth Sleepiness Scale was not a predictor variable in any regression model evaluated. Improvement of a predictive regression model for obstructive apnea in adult females was not achieved. Two-sample, unpaired, multiple t-tests (Bonferroni corrected p $\le$ 0.0045) showed significant differences between non-OSAS diagnosed sleepers and OSAS diagnosed sleepers for respiratory disturbance index (RDI) only