Independent and joint associations of reported household chemical product use and overweight/obesity with cardiovascular disease among older adults in China: a national cross-sectional study

Background Household chemicals are common indoor exposures among older adults, but their association with cardiovascular disease (CVD) and whether the association varies according to body weight status remains unclear. Methods Data were drawn from the 2018 Chinese Longitudinal Healthy Longevity Survey. The final analysis included 12,123 adults aged 65 years or older. Reported household chemical product use frequency was classified as low or high based on the median score of eight household chemical products. Overweight/obesity was defined as BMI ≥ 24.0 kg/m 2 . CVD was defined as a composite outcome including hypertension, heart disease, or stroke. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using binary logistic regression, with adjustment for demographic, socioeconomic, lifestyle, and health-related covariates. In addition, multiplicative and additive interactions were assessed using the product term and the relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI). Results High-frequency household chemical product use was associated with higher odds of CVD after full adjustment (OR = 1.34, 95% CI: 1.22, 1.48, p < 0.001). Overweight/obesity was also associated with higher odds of CVD (OR = 2.36, 95% CI: 2.12, 2.62, p < 0.001). In the combined analysis, participants with both high-frequency household chemical product use and overweight/obesity had the highest odds of CVD. Additive interaction between household chemical product use and overweight/obesity was observed (RERI = 0.58, 95% CI: 0.07, 1.09; p = 0.013), whereas no multiplicative interaction was detected. Conclusion Reported household chemical product use and overweight/obesity were each associated with higher odds of CVD among older adults. The combined presence of high-frequency household chemical product use and overweight/obesity was associated with the greatest odds of CVD, suggesting a potential joint contribution of environmental exposure and metabolic status to cardiovascular health.