PURPOSE: Obesity is a major risk factor for obstructive sleep apnea (OSA), but not all patients with obesity have OSA. Percentage predicted neck circumference (PPNC) is a useful clinical predictor of OSA but has not been studied specifically in obese patients with BMI ≥ 35. Our purpose is to evaluate if PPNC and other practical clinical predictors of OSA in this cohort (Obesity class II & III) may help stratify patients before referral for overnight polysomnography.
METHODS: A retrospective chart review of 128 patients with BMI ≥ 35, referred to our sleep center between October 2009 and February 2010 for evaluation of sleep disordered breathing and had overnight polysomnography, was performed. Eighty-six patients (67.2%) had Apnea Hypopnea Index (AHI) ≥ 10 and were considered to have significant OSA and forty-two patients (32.8%) did not have significant OSA (AHI < 10). The clinical parameters included: age, gender, race, snoring, neck circumference, PPNC, Epworth sleepiness score (ESS), witnessed apnea, waist/hip ratio, snoring, morning headache, diabetes mellitus, hypertension, coronary artery disease, congestive heart failure, stroke and smoking history. 1-sided Fisher exact test for categorical data & Student’s t-test for numerical data were used.
RESULTS: Our findings of 67% prevalence of significant OSA in class II & III obese patients are consistent with prior studies. Compared to patients who did not have significant OSA, patients with significant OSA were older (50.5 ± 12.7 years vs. 45.3 ± 12.8 years; p< 0.03), and had larger PPNC (108.5% ± 11.7 vs. 103.7% ± 14; p< 0.04). Other parameters did not reach statistical significance. The combination of PPNC ≥106% & age ≥ 49 years revealed the highest positive predictive value & specificity (0.89 and 0.91, respectively. LR 3.8).
CONCLUSION: This study demonstrates that age & PPNC are useful and practical clinical predictors of significant OSA in patients with BMI ≥ 35.
CLINICAL IMPLICATIONS: Among patients with BMI ≥ 35, the presence of OSA may be best predicted by a combination of age & PPNC.
DISCLOSURE: Md Islam, No Financial Disclosure Information; No Product/Research Disclosure Information