Prehypertension is associated with increased risk for incident hypertension. However, little is known about how frequently prehypertension converts to normotension, and which variables predict this conversion.Methods:
We identified 186 Japanese Americans with prehypertension (110 men, 76 women) aged 34–75 years (mean age of 52.3 years) who were followed at 5 and 10 years after enrollment. Blood pressure was measured with a mercury sphygmomanometer and average blood pressure was calculated. Subcutaneous adipose tissue, visceral adipose tissue (VAT), and subcutaneous thigh adipose tissue area were measured by computed tomography.Results:
Approximately one-third of those with prehypertension converted to normotension over 10 years of follow-up. Those who converted to normotension were younger, less obese, and had significantly lower baseline SBP, fasting glucose, cholesterol levels, and homeostasis model assessment insulin resistance compared with study participants who continued to have prehypertension or progressed to hypertension. With regard to body fat compartments, study participants with conversion to normotension showed a significantly smaller VAT area compared with the nonconversion group (P < 0.001); but, subcutaneous adipose tissue and subcutaneous thigh adipose tissue were not significant. In multivariate logistic regression analysis, baseline VAT was inversely associated with the conversion independent of age, sex, waist circumference, diabetes, fasting glucose, homeostasis model assessment insulin resistance, non-high-density lipoprotein cholesterol, and SBP [odds ratio per 1 SD VAT increment (95% confidence interval), 0.35 (0.15–0.80), P = 0.012].Conclusion:
This is the first prospective study showing the role of body fat distribution, determined by computed tomography scan, in predicting the natural history of prehypertension. Baseline VAT was inversely and independently associated with the conversion to normal blood pressure. No other adipose variable was significant. The mechanisms responsible for these observations remain to be elucidated.