Association of 6-year waist-circumference change with progression from prehypertension to hypertension: the Rural Chinese Cohort Study.

Whether dynamic change in waist circumference is associated with progression from prehypertension to hypertension is not well understood. We explored this issue. A total of 4221 prehypertensive adults ≥18 years were enrolled during 2007-2008 and followed up during 2013-2014. Participants were classified by percentage waist-circumference change at follow-up: ≤-2.5, -2.5 to ≤2.5, 2.5 to ≤5.0, and >5.0%. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with logistic regression models, with stable waist-circumference change (-2.5 to 2.5%) as the reference. During the 6 years of follow-up, 1464 prehypertensive patients (851 women) showed progression to hypertension, with an incidence rate of 32.7% for men and 36.3% for women. As compared with stable waist circumference, a waist-circumference gain > 5.0% was associated with increased hypertension risk: adjusted ORs (95% CI) were 1.08 (1.01-1.14) for men and 1.09 (1.04-1.15) for women. The risk also decreased significantly for men with ≥2.5% waist-circumference loss (OR = 0.94, 95% CI 0.88-1.00). We found a linear association between percentage waist-circumference gain and risk of progression from prehypertension to hypertension for both sexes by restricted cubic splines (pnonlinearity = 0.772 for men and 0.779 for women). For each 10% gain in waist circumference, the risk increased by 8% for men and 5% for women. The association remained significant for both sexes in a subgroup analysis by abdominal obesity at baseline. The long-term gain in waist circumference significantly increased the risk of progression from prehypertension to hypertension for both sexes in a rural Chinese population, regardless of abdominal obesity status at baseline.