The prevalence of metabolic syndrome in polycystic ovary syndrome in a South Indian population and the use of neck circumference in defining metabolic syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in young women with a high prevalence of insulin resistance (IR) and metabolic syndrome (MetS). The prevalence of MetS differs based on the defining criteria used. Neck circumference (NC) has been proposed as a surrogate marker of MetS which is simple and easy to perform in the outpatient setting. The aim of the study was to estimate the prevalence of metabolic syndrome in women with PCOS and to study the use of NC in defining metabolic syndrome. This was a prospective observational cross-sectional study involving 121 PCOS patients over a period of 2 years. The prevalence of metabolic syndrome was estimated using the modified Adult Treatment Panel (ATP) III criteria as well as the International Diabetes Federation (IDF) criteria. The Pearson correlation coefficient was used to find the degree of correlation between NC and waist circumference (WC). The Receiver operating characteristic (ROC) curves of NC were used to predict the metabolic syndrome. The independent sample t test and the Mann-Whitney U test were used for comparing the average NC and WC between the groups of patients with and without MetS. The prevalence of MetS was found to be 30.6 % using the modified ATP III criteria and 52 % using the IDF criteria. There is a statistically significant positive correlation between NC and WC (r = 0.758, p < 0.001). The mean NC is higher in patients who have MetS by both criteria (p < 0.001). Based on ROC curve analysis, the NC cutoff of 33.5 cm detected MetS (by IDF criteria) with a sensitivity of 60.3 % and a specificity of 70.7 % (area under ROC curve = 0.70, p < 0.001) and the NC cutoff of 33.87 cm detected MetS (by ATP III criteria) with a sensitivity of 73 % and a specificity of 69 % (area under ROC curve = 0.722 p < 0.001). The IDF criteria identified a higher number of PCOS subjects with MetS compared to the ATP III criteria. NC correlated very well with MetS as well as WC, and this could replace the waist circumference to define MetS in the future.