Predictive value of Metabolic Syndrome components in detecting the syndrome in patients with type 2 Diabetes Mellitus

Abstract

Background: Metabolic Syndrome (MetS) is a constellation of clinical features that increase cardiovascular morbidity and mortality in individuals. Up-to-date, there is no cheap, single surrogate test for MetS and current diagnostic criteria for the syndrome use scoring systems which are laborious, and the associated blood lipid tests are expensive and thus not adaptable to low resource countries such as Zambia.
Objective: The aim of the current study was to determine the predictive value of individual components of MetS in detecting the syndrome in patients with type 2 DM so as to explore simpler and cheaper alternative diagnostic approaches.
Materials and Methods: This was a cross-sectional hospital based study of 400 medical outpatients with type 2 DM. The National Cholesterol Education Program Adult Treatment Panel III (ATP III) was used as the standard diagnostic test and components of MetS that were measured included waist circumference, blood pressure, fasting blood sugar, fasting serum triglycerides and HDL cholesterol. We defined abdominal obesity as waist circumference ≥ 94cm for men and ≥80cm for women. The sensitivity, specificity, predictive values and likelihood ratios of individual components of MetS were determined.
Results: The prevalence of MetS using ATP III was 73% (91% in women and 50% in men; p<0.001).The presence of a large waist circumference had sensitivity and specificity of 90% with likelihood ratio of 9 and positive and negative predictive values of 96% and 78% respectively in predicting type 2 DM patients with MetS. Hypertension had sensitivity of 94% and poor specificity of 56% and thus a low likelihood ratio of 2. The positive and negative predictive values were 85% and 78% respectively. Both hypertriglyceridemia and low serum HDL levels had poor sensitivities of 42% and 28% but had high likelihood ratios (11 and 14 respectively) due to high specificities (96% for hypertriglyceridemia, 98% for low HDL). The negative and positive predictive values for hypertriglyceridemia were 97% and 38% respectively whereas low HDLhad 98% and 33% as positive and negative predictive values for MetS. The presence of a high BMI had sensitivity of 56%, specificity of 80%, likelihood ratio of 3 and positive and negative predictive values of 88% and 40% respectively.
Conclusions: In Zambian patients already suffering from type 2 DM, a large waist circumference is a fairly sensitive (90%) and specific (90%) test in predicting MetS with negative and positive predictive values of 96% and 78% respectively. And a type 2 DM patient with a large waist circumference is 9 times more likely to have MetS than one with normal waist circumference, with a posttest probability of 96%. Therefore, simple waist circumference measurement can be used alone as an alternative cheaper surrogate test to detect MetS in patients with type 2 DM.

Keywords: Metabolic Syndrome, Type 2 Diabetes Mellitus, Predictive value