Metabolic syndrome and cardiometabolic risk factors among indigenous Malaysians

Abstract

Objectives: This study was undertaken to investigate the occurrence of metabolic syndrome (MetS) and cardiovascular disease (CVD) risk in Orang Asli (OA), the indigenous people of Peninsular Malaysia. OA consist of Negrito, Proto-Malay, and Senoi groups who collectively comprise only 0.76% of the population of Peninsular Malaysia. Owing to the challenges in accessing their remote villages, these groups are often excluded in larger government health surveys. Although tropical diseases were scourges in the past, with rapid national development, many OA communities have been gradually urbanized. We believe an epidemiological transition is occurring and non-communicable diseases are on the rise.

Study design: A retrospective cross-sectional study.

Methods: Indigenous Malaysians (n = 629) from three major groups (Negrito, Proto-Malay, and Senoi) were recruited, after ethics approval and informed consent. Body mass index (BMI), body weight, height, waist circumference, and systolic and diastolic blood pressure were measured, and participants were examined for acanthosis nigricans. Venous blood samples were used for measurements of fasting blood sugar, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Insulin resistance was estimated using a surrogate measurement TG/HDL-C. The ratios of TC to HDL-C, and of LDL-C to HDL-C were determined. MetS was accessed according to the Joint Interim Statement of the IDF Tsak Force on Epidemiology and Prevention.

Results: MetS affected 29.57% of the OA population investigated and was significantly more prevalent (P < 0.05) in women than in men (35.25% vs 21.95%, P < 0.001). MetS prevalence was the highest among the Proto-Malays (39.56%), followed by Negritos (26.35%) and Senois (11.26%). The most prevalent risk factor among the Negritos with MetS was low HDL-C (95.35%), whereas central obesity was the most common risk factor among the Proto-Malays (82.91%). In contrast, hypertension was the commonest risk factor among the Senois with MetS (94.44%). Elevated TG/HDL-C ratios resulted in the highest risk for MetS among the OA population (relative risk [RR] = 7.01, 95% confidence interval [CI] = 3.58-13.72). The risk was almost four-fold among those with high TG (RR = 3.89, 95% CI = 3.08-4.91) and three-fold among those with BMI obesity (RR = 3.37, 95% CI = 2.61-4.36) and central obesity (RR = 2.99, 95% CI = 2.48-3.61).

Conclusions: This may well be the first comprehensive report about MetS in OA indigenous communities in Malaysia. We have shown that rapidly urbanized OA communities had significant prevalence of MetS and associated cardiometabolic risk factors. Major contributory factors may include changes from previous hunter-gatherer lifestyles and subsistence diets to more urbanized lifestyles and easier access to high calorie foods.

Keywords: Cardiovascular disease risk; Indigenous communities; Metabolic syndrome.