The rates of cardiovascular disease and death are higher in rural than urban areas and in men than in women, according to two PURE substudies conducted in China and in South Asia, published June 22 in the European Heart Journal.

Data from the prospective PURE study were examined to determine the incidence of cardiovascular disease and cardiovascular death. The mean follow-up was about 11 years for both studies and the age-and sex-adjusted incidence of a cardiovascular event and death were calculated for the overall cohorts, by urban or rural location, by sex, and by country/province.

The cohort in China included 47,262 patients from 115 communities in 12 provinces. Their mean age was 51.1 years, 58.2% were female, 49.2% were from urban areas and nearly 60% were from the Eastern region of the country. The cohort from South Asia included 33,583 patients from India (86.1%), Bangladesh (8.7%), and Pakistan (5.2%). Their mean age was 48.4 years and 55.8% were women.

Among participants with no history of cardiovascular disease, 12 common modifiable risk factors were examined to determine their population-attributable factors (PAFs). The metabolic risk factors were hypertension, diabetes, abdominal obesity, non-HDL-C; the behavioral risk factors were tobacco use, alcohol use, diet, physical activity; and also examined were education, grip strength, depression and air pollution. Ratios were calculated using Cox regression models, and average PAFs were calculated for cardiovascular disease and each risk factor group.

Results for both substudies were similar and showed that the rates of cardiovascular disease and cardiovascular death were higher in men compared with women and in rural compared with urban areas. Cardiovascular disease was the leading cause of death in China (36%) and in South Asia (35.5%).

In China, the rates of cardiovascular disease and death were 8.35 and 5.33 per 1,000 person-years, respectively, and rates of death were higher in the central and western regions of China than the eastern region. The modifiable risk factors studied collectively contributed to 59% of the PAF for cardiovascular disease and 56% of the PAF for death in China. Metabolic risk factors accounted for the largest proportion of cardiovascular disease (PAF of 41.7%); hypertension was the most important risk factor (25.0%), followed by low education (10.2%), high non-HDL-C (7.8%) and abdominal obesity (6.9%). The largest risk factors for death were hypertension (10.8%), low education (10.5%), poor diet (8.3%), tobacco use (7.5%), and household air pollution (6.1%).

In South Asia, the incidence of cardiovascular disease was highest in Bangladesh, while the mortality rate was highest in Pakistan. The age- and sex-standardized incidence of cardiovascular disease was 5.12 per 1,000 person-years and it was 8.66 for death in the overall South Asian cohort. The modifiable risk factors studied contributed to approximately 64% of the PAF for cardiovascular disease and 69% of the PAF for mortality. The largest PAFs for cardiovascular disease were attributable to hypertension (13.1%), high non-HDL-C (11.1%), diabetes (8.9%), low education (7.7%), abdominal obesity (6.9%) and household air pollution (6.1%); for death these were education (18.9%), low grip strength (14.6%), poor diet (6.4%), diabetes (5.8%), tobacco use (5.8%) and hypertension (5.5%).

Philip Joseph, MD, et al., note that “these data reflect the triple burden of disease (e.g., noncommunicable disease, communicable diseases, and injuries) currently driving mortality in the region as communities continue to undergo rapid epidemiological transition.” Sidong Li, et al., add that comparing the “differing findings highlight the value of region-specific data to better inform how health policies should be tailored in different regions of the world.”

In an accompanying editorial comment, Eva Prescott, MD, DMSc, notes, “social conditions are a fundamental cause of disease. Over the last decades, epidemiological studies have been enormously successful in identifying the major risk factors for cardiovascular disease.” She adds that “social factors, including education, socioeconomic status, and cultural context, are upstream drivers of modifiable risk factors. This must be kept in mind if we are to achieve lower rates of [cardiovascular disease] and fewer disparities in a global context.”

Clinical Topics: Cardiovascular Care Team, Diabetes and Cardiometabolic Disease, Prevention, Diet, Exercise, Hypertension

Keywords: Communicable Diseases, Epidemiologic Studies, Heart Disease Risk Factors, Health Policy, Social Class, Social Factors, Social Conditions, Noncommunicable Diseases, Cause of Death, Diet, Tobacco Use, Exercise, Diabetes Mellitus, Hypertension, Risk Factors, Follow-Up Studies, Depression, Incidence, Prospective Studies, Obesity, Abdominal, Cardiovascular Diseases

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