Neck Circumference as an Anthropometric Indicator of Central Obesity in Patients with Prediabetes: A Cross-Sectional Study.

Measurement of waist circumference has substantial variability and some limitations, while neck circumference is a simple and reliable anthropometric measure. This study aimed to assess the association between neck circumference and waist circumference and to identify the best cutoff of neck circumference that could predict central obesity in prediabetic patients. This cross-sectional study included adult patients with prediabetes, defined as having fasting plasma glucose levels ranging from 100 to 125 mg/dL or HbA1c ranging from 5.7 to 6.49%, who visited the outpatient clinic of Family Medicine Department, Ramathibodi Hospital, Thailand, during October 2014 and March 2016. Neck circumference was measured from the level just below the laryngeal prominence perpendicular to the long axis of the neck. Central obesity was defined as having waist circumference measurements greater than 90 and 80 cm for males and females, respectively. The correlation between neck circumference and waist circumference was explored by applying pairwise correlation coefficient. Receiver operating characteristic (ROC) curve analysis was performed and Youden index equal to "sensitivity - (1-specificity)" was calculated. Neck circumference that yielded the maximum Youden index was determined as the optimal cutoff point for prediction of central obesity. There were 1,534 patients eligible for this study. After adjusting for covariables, neck circumference was found to be significantly associated with waist circumference in both females and males, with β-coefficients of 1.01 (95% CI: 0.83, 1.20) and 0.65 (95% CI: 0.46, 0.85), respectively. After applying the ROC analysis, neck circumferences ≥ 32 cm in females and ≥ 38 cm in males were determined as the best cutoff values to predict central obesity. Neck circumference is strongly correlated with waist circumference in prediabetics and should be considered as an alternative to the waist circumference measurement in screening for central obesity.