Objectives We sought to examine prevalence and clustering of seven selected cardiovascular disease risk factors (CDRFs) by blood pressure level among Chinese hypertensive population.
Methods Data from the 2010 China Chronic Disease and Risk Factor Surveillance, a nationally representative survey assessing chronic diseases and related risk factors, were used. A total of 36,971 respondents with hypertensive condition (SBP ≥ 140 mm Hg, DBP ≥ 90 mmHg, or self-reported hypertension) were included in the study. We examined prevalence for seven CDRFs and their clustering (mean number of CDRFs) by blood pressure (BP) levels, such as current smoking, excessive drinking (daily consumption of alcohol ≥ 25 g for men, 15 g for women), insufficient intake of fruit and vegetables (≤ 400 g of fruit and vegetables per day), physical inactivity (≤ 150 minutes of moderate-intensity activity per week or equivalent), overweight or obesity (BMI ≥25), raised blood glucose (fasting plasma glucose value ≥ 7.0 mmol/L or on medication for raised blood glucose), and raised total cholesterol (total cholesterol ≥ 5.0 mmol/L). According to 2007 WHO/ISH definitions and classification of BP levels, the BP of each respondent was classified into six levels: optimal, normal, high-normal, stage 1 hypertension, stage 2 hypertension, and stage 3 hypertension. Ordinal logistic regression was used to access independent effect of the BP levels on clustering of CDRFs, with adjustment of demographic and social-economic covariates. SAS carried out all computation and accounted for the complex sampling design of the survey.
Results Of seven CDRFs, five were most prominent among respondents with stage 3 hypertension: 56.1% (95% CI: 52.1% - 60.2%) for insufficient intake of fruit and vegetables, 27.7% (24.4% - 31.0%) for physical inactivity, 54.9% (51.3% - 58.6%) for overweight or obesity, 17.9% (16.0% - 19.9%) for raised blood glucose, and 29.2% (26.8% - 31.5%)for raised total cholesterol. Individuals with stage 1 hypertension had the highest prevalence of current smoking (29.7%, 95% CI: 28.4% - 31.0%) and excessive drinking (17.1%, 95% CI: 15.7% - 18.5%). Clustering of CDRFs increased almost with BP levels. The mean number of CDRFs was 1.74 (95% CI: 1.54 – 1.93) for respondents with optimal BP, 2.00 (1.91 – 2.09) for normal BP, 2.10 (2.01, 2.19) for high-normal BP, 2.04 (1.98 – 2.10) for stage 1 hypertension, 2.16 (2.09 – 2.23) for stage 2 hypertension, and 2.26 (2.18 – 2.35) for stage 3 hypertension. Multiple Ordinal logistic regression showed that, compared with optimal BP, individuals with stage 3 hypertension had 2.39 times the cumulative odds (95%CI: 1.73 – 3.32) of having more number of CDRFs, stage 2 hypertension had 1.97 times (1.43 – 2.73), stage 1 hypertension had 1.63 times (1.20 – 2.22), high-normal BP had 1.61 times (1.20 – 2.17), and normal BP had 1.40 times (1.00 – 1.97).
Conclusions The worse Chinese hypertensive population had their BP controlled, the more CDRFs appeared to be carried by them, regardless of demographic and social-economic status. This implies that, compared to those with good BP management, hypertensive individuals with poor BP control are not only more likely to be exposed to sequela attributable to hypertension, but also many other chronic diseases. Therefore, public health programs to enhance BP management skill among those with poor BP control should also take into consideration reducing CDRFs among them.