Introduction: Obesity and male gender are the main risk factors for the development of obstructive sleep apnoea (OSA); however, some epidemiological data has shown that neck circumference (NC) > or = 43 cm is a better predictor of obstructive event frequency than body mass index (BMI). The aim of this study was to assess the relation between NC and BMI on OSA severity in males.
Material and methods: The subjects completed a sleep questionnaire and Epworth sleepiness scale before the sleep study (full polysomnography or PolyMesam study). Authors studied 133 consecutive males with confirmed OSA (AHI/RDI > 10, Epworth score > 9 points). Chest X-ray, spirometry, arterial blood gases, ECG, blood morphology and biochemistry were performed during treatment trial with autoCPAP.
Results: Subjects presented with obesity--BMI = 35.8 +/- 6.1 kg/m2, NC = 46 +/- 3.4 cm and severe disease--AHI/RDI = 45.3 +/- 23.6. Mean age was 52.7 +/- 11.3 years. The majority of subjects had NC > or = 43 cm (116 pts, 87.2% - group 1), 17 pts (12.8% - group 2) had NC < 43 cm had 17 pts. Comparison of both groups showed significant differences only for BMI (group 1 - 36.8 +/- 5.7, group 2 - 28.6 +/- 3.7; p < 0.0001). Linear regression analysis revealed significant correlation between NC and AHI/RDI (R2 = 0.07, r = 0.26; p = 0.003); however, the correlation between BMI and AHI/RDI was stronger (R2 = 0.14, r = 0.37; p < 0.0001). In multiple linear regression analysis we found significant correlation between AHI/RDI and age (beta = -0.31, p = 0.003) and BMI (beta = 0.34, p = 0.02).
Conclusions: The strongest correlation between AHI/RDI, younger age and BMI. Correlation between neck circumference and AHI/RDI was significant but less when compared to BMI.