Introduction:
Neck circumference (NC) is one of the parameters to be associated with obstructive sleep apnea (OSA). However, there is lack of research data reflecting our local population with regard to the size of NC in relation to the severity of OSA.

Aim:
The primary goal of this study was to investigate the association of NC with OSA and to compare NC with other parameters as a predictor of the severity of OSA, among local population. This future reliable parameter can be used in front line clinics as to guide the referral to the tertiary center.

Material and methods:
This was a prospective study conducted upon 120 OSA patients, aged within 18–55 years, who underwent overnight polysomnography with apnea/hypopnea index more than 5 and met all the inclusion criteria. All patients completed the Epworth sleepiness scale questionnaire while all the parameter measurement including height, weight, body mass index and NC were documented.

Results and discussion:
A Pearson correlation analysis showed NC was significantly associated with OSA (r = 0.495, P < 0.001) while multiple linear regression model displayed an association between NC and lowest SpO₂ desaturation during sleep (LSAT) as predictors of OSA severity (P < 0.001). Mean value of NC also significantly higher among severe OSA compared to mild OSA (42.7 ± 0.9 cm vs. 39.0 ± 1.3 cm; P < 0.001).

Conclusions:
NC was significantly associated with OSA and both NC and LSAT were significantly correlated as predictors of OSA severity.