Children, Obesity, and High Blood Pressure: Asian Populations at High Risk

Childhood obesity is increasingly being recognized as a major public health problem worldwide. Elevated blood pressure (BP) in youth has been associated with increased atherosclerosis, and tracks into adulthood.1 Hypertension is a leading contributor to the global burden of cardiovascular morbidity and mortality.2 In this issue of AJH, Ke and colleagues present their important work which highlights the enhanced susceptibility of South East (SE) Asian-origin children in Sydney to obesity and associated hypertension.3 In a cross-sectional analysis of 216 children aged 8–9 years of SE Asian and 381 of Australian origin from 75 inner city schools in Sydney, Ke et al. observed that increased obesity indices (body mass index (BMI), waist circumference, skin fold thickness) were associated with elevated levels of BP.3 These relationships were more pronounced in SE Asians compared to Australians, and persisted even with lower (Asian-specific) BMI thresholds for defining overweight or obesity in the former. In addition, longitudinal follow-up of about half of this cohort revealed that an increase in adiposity over 3 years was associated with rise in systolic BP in SE Asian but not in Australian children. Moreover, a significant interaction was also detected between baseline BMI and change in BMI over 3 years on systolic BP in SE Asian children, which suggested that the rise in BP due to weight gain is exaggerated in thinner SE Asian youth. Our previous report based on the analysis of large population-based surveys demonstrated higher BMI-adjusted BP in native South Asian children in Pakistan compared to native white counterparts in the United States.4 Further, adiposity during childhood has been associated with impaired fasting glucose or diabetes in young adulthood.5 The findings by Ke and colleagues add valuable knowledge to the existing evidence on deleterious impact of excessive weight gain on BP levels of children of Asian origin. A number of limitations of this study need to be recognized, including the small sample size, low overall recruitment rate (40%), high proportion of drop-outs (54%) and with characteristics that can potentially influence BP levels (e.g., more obese, less physically activity), and lack of data on pubertal staging. However, the number of children enrolled in the study was adequate for detection of significant interactions between ethnicity and obesity indices on BP. These interactions were consistent in both cross-sectional and prospective components of the study, and were present regardless of whether the key variables were expressed as continuous or categorical terms, adding strength to the reliability and internal validity of the findings. Future studies will be needed to confirm these observations and to disentangle the relative contributions of genetic, behavioral, and other environmental factors responsible for the ethnic differences in the relationship of adiposity and BP. It also remains to be assessed whether these differences are translated into impact of BP on end-organ damage. Perhaps more importantly, findings of this nature call attention to the urgent need for proactive measures against an anticipated explosive rise in the burden of childhood obesity and hypertension in migrant as well as native Asian communities. Many of these economically challenged countries are already experiencing a double burden of undernutrition along with rising rates of overweight during childhood—a combination shown by Ke et al. to be particularly worrisome with regard to development of hypertension. On the brighter side, evidence from industrialized nations suggests success of school-based programs of physical activity and nutrition education in reducing obesity and BP levels.6 Such programs will need to be assessed in various ethnic populations after modifications to suit cultural acceptability for optimal effectiveness in various ethnic populations. In this regard, the article by Ke et al. is a timely contribution for underscoring the need for innovation in programs for prevention of obesity and hypertension in the vulnerable Asian youth. The author declared no conflict of interest.