Association of combined body mass index and central obesity with cardiovascular disease in middle-aged and older adults: a population-based prospective cohort study

Cardiovascular diseases (CVDs) pose a significant threat to public health. Evidence indicates that the combination of central obesity and normal body mass index (BMI) is associated with an increased risk of cardiovascular disease and mortality. However, limited evidences exists in middle aged and elderly adults in China. This was a prospective cohort study that utilized a nationally representative sample of 6,494 adults aged 45 years and above. These individuals participated in the China Health and Retirement Longitudinal Study spanning from 2011 to 2018. Height, weight and waist circumference (WC) were measured, and BMI was calculated by height and weight. Other variables were obtained through self-reported questionnaires. Association analysis was conducted using Cox proportional hazard regression models. A total of 10,186 participants were investigated, with 57,185 person-years of follow-up. During this period, 1,571 CVDs occurred, including 1,173 heart diseases and 527 strokes. After adjusting for various factors including age, gender, education, marital status, smoking status, alcohol intake, social activity, hypertension, dyslipidemia, diabetes, cancer, chronic lung diseases, liver disease, kidney disease, digestive disease, ENP(emotional, nervous, or psychiatric problems), memory related disease, arthritis or rheumatism, asthma, self-rated health and depression, the results revealed that compared to those with normal WC normal body mass index (BMI), individuals with central obesity normal BMI had a 27.9% higher risk of CVD incidence (95% confidence interval CI:1.074–1.524), and a 33.4% higher risk of heart disease incidence (95% CI:1.095–1.625), while no significant association was found with stroke. Additionally, those with normal WC high BMI showed a 24.6% higher risk of CVD incidence (95% CI:1.046–1.483), and a 29.1% higher risk of heart disease incidence (95% CI:1.045–1.594), again with no significant association with stroke. Finally, individuals with central obesity high BMI exhibited a 49.3% higher risk of CVD incidence (95% CI:1.273–1.751), a 61% higher risk of heart disease incidence (95% CI:1.342–1.931), and a 34.2% higher risk of stroke incidence (95% CI:1.008–1.786). Age- and sex- specific analyses further revealed varying trends in these associations. We discovered that the combined association of body mass index(BMI) and central obesity with CVD incidence exhibited a significantly enhanced predictive value. Specifically, a high BMI with central obesity was notably linked to an increased risk of CVD incidence. Additionally, central obesity with a normal BMI or a normal WC coupled with a high BMI significantly augmented the risk of heart disease incidence, but not stroke. Notably, male and middle-aged adults demonstrated a greater propensity for heart disease incidence. Our study underscores the importance of maintaining an optimal BMI and preventing abdominal obesity in promoting cardiovascular health.