BMI and risk of all-cause mortality in normotensive and hypertensive adults: the rural Chinese cohort study

Objective: The impact of baseline hypertension status on the BMI-mortality association is still unclear. We aimed to examine the moderation effect of hypertension on the BMI-mortality association using a rural Chinese cohort. Design: In this cohort study, we investigated the incident of mortality according to different BMI categories by hypertension status. Setting: Longitudinal population-based cohort. Participants: 17 262 adults >= 18 years were recruited from July to August of 2013 and July to August of 2014 from a rural area in China. Results: During a median 6-year follow-up, we recorded 1109 deaths (610 with and 499 without hypertension). In adjusted models, as compared with BMI 22-24 kg/m(2), with BMI <= 18, 18-20, 20-22, 24-26, 26-28, 28-30 and >30 kg/m(2), the hazard ratios for mortality in normotensive participants were 1 center dot 92 (95% CI 1 center dot 23, 3 center dot 00), 1 center dot 44 (95% CI 1 center dot 01, 2 center dot 05), 1 center dot 14 (95% CI 0 center dot 82, 1 center dot 58), 0 center dot 96 (95% CI 0 center dot 70, 1 center dot 31), 0 center dot 96 (95% CI 0 center dot 65, 1 center dot 43), 1 center dot 32 (95% CI 0 center dot 81, 2 center dot 14) and 1 center dot 32 (95% CI 0 center dot 74, 2 center dot 35), respectively, and in hypertensive participants were 1 center dot 85 (95% CI 1 center dot 08, 3 center dot 17), 1 center dot 67 (95% CI 1 center dot 17, 2 center dot 39), 1 center dot 29 (95% CI 0 center dot 95, 1 center dot 75), 1 center dot 20 (95% CI 0 center dot 91, 1 center dot 58), 1 center dot 10 (95% CI 0 center dot 83, 1 center dot 46), 1 center dot 10 (95% CI 0 center dot 80, 1 center dot 52) and 0 center dot 61 (95% CI 0 center dot 40, 0 center dot 94), respectively. The risk of mortality was lower in individuals with hypertension with overweight or obesity v. normal weight, especially in older hypertensives (>= 60 years old). Sensitivity analyses gave consistent results for both normotensive and hypertensive participants. Conclusions: Low BMI was significantly associated with increased risk of all-cause mortality regardless of hypertension status in rural Chinese adults, but high BMI decreased the mortality risk among individuals with hypertension, especially in older hypertensives.