Effects of body mass index on blood pressure control rate in elderly coronary heart disease outpatients with hypertension

Abstract

Objective: To explore the influences of body mass index (BMI) on blood pressure control rate in elderly coronary heart disease (CHD) outpatients with hypertension. Methods: In this multicenter, non-intervention and cross-sectional survey, the elderly coronary heart disease patients with hypertension aged 60 years or over were recruited from 165 hospitals in 21 provinces or cities across China from April to July 2011, and 5 140 cases of elderly CHD patients with hypertension were finally included into the study. The cases were divided into low BMI group (n=130 cases), normal body mass index (BMI) group (n=1 390 cases), overweight (n=2 418 cases), obesity group (n=662 cases) according to the different levels of BMI. Clinical data and blood pressure control rate were compared among the groups, and relationships of different BMI levels with blood pressure control rate were analyzed by the binary classification unconditioned Logistic regression equation. Results: There was a statistically significant difference in blood pressure control rate of general population, men and women patients among low BMI group, normal BMI group, overweight and obesity group (χ2=66.346, 58.995, 26.044, respectively, P<0.001), blood pressure failure rate in obesity group (73.7%) was higher than that in overweight group (65.8%) and normal BMI group (57.5%) (P<0.05), and overweight group was also higher than normal BMI group (P<0.05); blood pressure failure rate in obesity men was higher than that in normal BMI and low BMI group (P<0.05), overweight group was higher than normal BMI group (P<0.05); blood pressure failure rate in obesity women was higher than that in normal BMI and low BMI group (P<0.05). There was a statistically significant difference in blood pressure control rate of different age groups (60-70, 71-80, >80 years old) among low BMI group, normal BMI group, overweight and obesity group (χ2=37.729, 20.007, 15.538, respectively, P<0.001). Blood pressure failure rate in obesity patients with 60-70 years old was higher than that in overweight and normal BMI group (P<0.05), blood pressure failure rates in obesity and overweight patients with 71-80 and > 80 years old were also higher than those in normal BMI group (P<0.05). Multivariable Logistic regression equation showed that overweight in overall population (OR=1.313, 95%CI 1.170-1.731, P<0.05), obesity (OR=2.295, 95%CI 2.295-1.496, P<0.05) were independent risk factors for blood pressure failure rate, in addition, obesity was also risk factor for blood pressure failure rate in men and women patients. Conclusions: Increased BMI has an adverse effect on blood pressure control rate in elderly CHD outpatients with hypertension, and may be the independent risk for blood pressure failure rate in those patients. Much more attention should be given to control BMI level so as to increase the blood pressure success rate and improve the patients' prognosis.