PURPOSE: Neck circumference (NC) is one of the important anthropometric variables in predicting presence of obstructive sleep apnea (OSA). The role of NC in non-obese patients with OSA is not well studied. The aim of our study is to evaluate the role of NC as a predictor for OSA in non-obese patients with OSA and study the influence of gender in this cohort.
METHODS: A retrospective study was conducted. Patients referred to our sleep lab for full polysomnography were evaluated. We included patients who were not obese (BMI<30) with a diagnosis of OSA (RDI>5). NC, height and weight were recorded at the time of polysomnography. A NC of >16 inches for women and >17 inches for men was used as a cut off as being abnormal.
RESULTS: Two hundred and sixty six patients met our inclusion criteria. The mean age was 60.4±13.9. The women were older when compared to men (63.6±10.6 vs. 58.7±15.1 p0.002). The BMI was comparable between the two groups. Men, as expected, had more severe OSA than women (RDI: 28.4±20.2 vs.22.7±20.4 p = 0.03). Also, men had a larger NC (16.3±1.08 vs. 14.2±1.4 p<0.0001). Eleven (12%) women had an abnormal NC while 60(34%) men had an abnormal NC ( Table 1). NC was not seen to correlate with severity of OSA in both males and females (r = 0.126 and 0.301 respectively; p = 0.767).
CONCLUSION: In non-obese patients with OSA, nearly a third of men, but only a minority of women, demonstrate abnormal NC. In non-obese patients with OSA, no correlation between NC and OSA is seen.
CLINICAL IMPLICATIONS: Various anthropometric measurements are used for screening OSA. NC is the best studied and is shown to be a good correlate of severity of OSA.Our data suggests that in non-obese patients with OSA, abnormal NC is prevalent in men but not in women. The NC correlates poorly with severity of OSA in this subgroup.Further studies directed at defining the craniofacial phenotype and gender differences in this cohort is necessary.
DISCLOSURE: Gnananandh Jayaraman, No Financial Disclosure Information; No Product/Research Disclosure Information