-
With rapid economic development and population aging, China has experienced an epidemic of hypertension. In comparison with general population, hypertensive patients have elevated heart rate (HR). Previous studies have documented the effect of elevated HR on all-cause and cardiovascular mortality (1), and higher HR and blood pressure can work synergistically to promote negative health outcomes (2). As a result, monitoring both blood pressure and HR among hypertensive patients is necessary. Although treatment and control of hypertension are essential for preventing adverse cardiovascular events, their roles in reducing HR are not fully understood. In addition, the extent to which such beneficial effects, if any, are modified by individual-level characteristics remains unexplored. In this study, we recruited a nationally representative sample of the general population from the China Chronic Disease and Risk Factors Surveillance (CCDRFS) in 2015 and collected their data on HR, blood pressure, and antihypertensive treatment. We found that the risk of increased HR was relatively lower in subjects with treated and controlled hypertension, although it was still significant. Furthermore, the impact on HR varied by subgroups of sex, marital status, smoking status, and physical activity. These results suggest that more efforts aiming to improve blood pressure control and promote healthy lifestyles are required to better regulate HR among hypertensive patients.
CCDRFS was a national survey of Chinese adults aged 18 years old and above and the population in this study were from the wave conducted in 2015. Multistage and cluster-randomized sampling was conducted in 298 counties/districts across 31 provincial-level administrative divisions (PLADs), thus providing a nationally representative sample. A questionnaire covering sociodemographic and lifestyle factors, history of hypertension treatment, and anthropometric measurements were administered to each subject by trained personnel. Among the 189,605 respondents (response rate 95.4%), 7,249 subjects had missing data on blood pressure or HR and 10,194 subjects had incomplete covariates, which resulted in the inclusion of 172,162 subjects in main analyses. Hypertension status was classified as follows: a) not treated (newly diagnosed or not treated with antihypertensive drugs); b) treated and not controlled (treated with antihypertensive drugs and systolic/diastolic blood pressure ≥140/90 mmHg); and c) treated and controlled (treated with antihypertensive drugs and systolic/diastolic blood pressure <140/90 mmHg). Increased HR was defined as more than 80 beats per minute (bpm), which was in accordance with the consensus of the Chinese Specialized Committee on Hypertension ( 3).
Standard descriptive statistics were presented by calculating mean and standard deviation for continuous variables and frequency and proportion for categorical variables. To account for correlation between subjects from the same cluster, a generalized linear mixed model with random intercepts for each county/district was employed to examine the associations between hypertension status and increased HR [expressed as odds ratio (OR) and 95% confidence interval (95% CI)]. Model 1 included age, sex, ethnicity, education, marital status, and household income as confounding variables. Model 2 additionally adjusted for smoking, drinking, exercise, salt intake, obesity, and dyslipidemia. In addition, subgroup analyses were also performed to check the modification effects of aforementioned factors. Because biological interactions had more implications in terms of public health, relative excess risk due to interaction (RERI) and attributable proportion (AP) were used to assess interaction at the additive scale (4). RERI and AP>0 meant more than additivity, and otherwise less than additivity. All statistical analyses were performed using R software (version 3.6.0, R Foundation for Statistical Computing), and statistical significance was defined as two-sidedp<0.05.
Data were available for 172,162 subjects aged ≥18 years, whose characteristics were similar with those excluded (n=17,443) except that they exhibited higher likelihood of being ethnically Han and physically active. Compared with non-hypertensive subjects, hypertensive patients were more likely to be older, less educated, poorer, obese, lipid dysregulated, and having higher salt intake (Table 1). Of the 68,405 hypertensive patients, 65.0% had untreated hypertension, 26.3% had treated and uncontrolled hypertension, and 8.7% had treated and controlled hypertension.
Variable Non-hypertensive subjects (n=103,757) Hypertensive subjects Total
(n=68,405)Not treated (n=44,435) Treated and not controlled (n=18,019) Treated and controlled (n=5,951) Age (mean±SD) 47.6±14.0 59.3±12.0 57.6±12.5 62.8±10.2 62.2±10.1 Men (n, %) 46,672 (45.0) 33,474 (48.9) 23,016 (51.8) 7,787 (43.2) 2,671 (44.9) Ethnically Han (n, %) 90,567 (87.3) 61,747 (90.3) 39,483 (88.9) 16,662 (92.5) 5,602 (94.1) Senior high school or above (n, %) 24,491 (23.6) 10,451 (15.3) 6,438 (14.5) 2,599 (14.4) 1,414 (23.8) Married (n, %) 94,568 (91.1) 62,125 (90.8) 40,567 (91.3) 16,179 (89.8) 5,379 (90.4) Household income (n, %) <10,000 CNY 9,024 (8.7) 8,596 (12.6) 5,563 (12.5) 2,472 (13.7) 561 (9.4) 10,000–49,999 CNY 48,186 (46.4) 31,592 (46.2) 21,052 (47.4) 8,136 (45.2) 2,404 (40.4) ≥50,000 CNY 30,074 (29.0) 17,028 (24.9) 10,026 (22.6) 4,795 (26.6) 2,207 (37.1) Don’t know/refuse to answer 16,473 (15.9) 11,189 (16.3) 7,794 (17.5) 2,616 (14.5) 779 (13.1) Current smoking (n, %) 27,247 (26.3) 17,786 (26.0) 12,762 (28.7) 3,755 (20.8) 1,269 (21.3) Current drinking (n, %) 38,430 (37.0) 24,639 (36.0) 17,467 (39.3) 5,316 (29.5) 1,856 (31.2) Physical inactivity (n, %) 18,249 (17.6) 12,985 (19.0) 8,491 (19.1) 3,373 (18.7) 1,121 (18.8) High salt intake (n, %) 62,621 (60.4) 43,909 (64.2) 28,699 (64.6) 11,744 (65.2) 3,466 (58.2) Obesity (n, %) 10,117 (9.8) 14,409 (21.1) 8,293 (18.7) 4,803 (26.7) 1,313 (22.1) Dyslipidemia (n, %) 35,565 (34.3) 32,139 (47.0) 18,910 (42.6) 9,926 (55.1) 3,303 (55.5) Table 1. General characteristics of subjects aged 18 years old or above by hypertension status in China, 2015.
As shown in Table 2, the HR of hypertensive subjects was 1 bpm higher than non-hypertensive subjects (76.4 vs. 75.4, p<0.001), and the corresponding prevalence of increased HR was 33.3% and 28.4%. Subjects with untreated or treated and uncontrolled hypertension had similar prevalence with overall hypertensive subjects (33.5% and 34.0%, respectively), whereas subjects with treated and controlled hypertension had prevalence closer to non-hypertensive subjects (30.3%). Further stratified analyses by sociodemographic, behavioral, and biological factors showed that the prevalence was significantly higher among people who were younger, female, unmarried, drinker, less physically active, obese, or with dyslipidemia (Supplementary Table S1). Results of the mixed effect logistic model supported these differences. After adjusting for covariates, the odds of increased HR was 35% higher for untreated hypertension (OR=1.35, 95% CI: 1.32 to 1.39), 40% higher for treated and uncontrolled hypertension (OR=1.40, 95% CI: 1.34 to 1.45), and 18% higher for treated and controlled hypertension (OR=1.18, 95% CI: 1.11 to 1.25).
SBP (mmHg, mean±SD) DBP (mmHg, mean±SD) HR (bpm, mean±SD) HR >80 bpm
(n, %)OR (95% CI) Model 1* Model 2† Non-hypertensive subjects 121.1±10.7 73.8±8.1 75.4±10.4 29,440 (28.4) ref ref Total hypertensive subjects 153.6±17.9 86.8±11.5 76.4±11.8 22,800 (33.3) 1.39 (1.36 to 1.42) 1.35 (1.32 to 1.38) Not treated 153.8±15.5 87.4±11.0 76.5±11.8 14,872 (33.5) 1.39 (1.35 to 1.42) 1.35 (1.32 to 1.39) Treated and not controlled 161.5±18.2 88.7±11.9 76.6±12.1 6,122 (34.0) 1.46 (1.41 to 1.51) 1.40 (1.34 to 1.45) Treated and controlled 128.5±8.5 76.4±7.9 75.9±11.0 1,806 (30.3) 1.23 (1.16 to 1.31) 1.18 (1.11 to 1.25) Abreviation: SBP=systolic blood pressure; DBP=diastolic blood pressure; HR=heart rate; OR=odds ratio; CI=confidence interval; REF=reference.
*Adjusted for age, sex, ethnicity, education, marital status, and household income.
†Adjusted for the same covariates as model 1 plus smoking, drinking, physical activity, salt intake, obesity, and dyslipidemia.Table 2. Blood pressure, heart rate, and risk of increased heart rate of subjects aged 18 years old or above by hypertension status in China, 2015.
Furthermore, the RERI was 0.17 (95% CI: –0.03 to 0.36) for smoking, 0.22 (95% CI: –0.01 to 0.45) for marital status, and 0.19 (95% CI: 0.01 to 0.36) for physical activity, suggesting synergistic effects of smoking, unmarried, or physical inactivity and treated and controlled hypertension (Table 3). In contrast, the RERI was –0.33 (95% CI: –0.50 to –0.16) for sex, which indicated that the joint effects of being women and treated and controlled hypertension were less than expected sum of the individual effects.
Item OR (95% CI)* Additive interaction RERI (95% CI) AP (95% CI) Sex Men 1.42 (1.30 to 1.55) −0.33 (−0.50 to −0.16) −0.22 (−0.34 to −0.10) Women 1.04 (0.97 to 1.13) Marital status Married 1.18 (1.11 to 1.26) 0.22 (−0.01 to 0.45) 0.13 (0.00 to 0.26) Not married 1.28 (1.07 to 1.53) Smoking status Non-smoker 1.16 (1.09 to 1.24) 0.17 (−0.03 to 0.36) 0.11 (−0.01 to 0.23) Smoker 1.31 (1.15 to 1.48) Physical inactivity No 1.18 (1.10 to 1.26) 0.19 (0.01 to 0.36) 0.12 (0.01 to 0.23) Yes 1.27 (1.11 to 1.44) Abreviation: RERI=relative excess risk due to interaction; AP=attributable proportion; CI=confidence interval.
*Adjusted for age, ethnicity, education, household income, drinking, salt intake, obesity, dyslipidemia, and for sex, marital status, smoking, physical activity when appropriate. Reference category: non-hypertensive subjects.Table 3. Additive interaction of treated and controlled hypertension and several characteristics on increased heart rate in China, 2015.
HTML
Citation: |