Association between chronic lung disease and chronic heart disease among middle-aged and older adults in India: A gender-stratified cross-sectional analysis

Chronic heart disease (CHD) and chronic lung disease (CLD) are major contributors to morbidity and mortality among ageing populations, often sharing common risk factors and biological pathways. Despite evidence of cardiopulmonary interactions, few studies in India have examined gender differences and effect modification in the association between CLD and CHD using nationally representative data. This study estimates the prevalence of CLD and CHD among Indian adults aged ≥45 years, examines their association, and explores gender differences in the distribution and contribution of BMI, self-rated health, hypertension, diabetes, cancer, stroke, and high cholesterol within this association. We analysed cross-sectional data from 60,632 respondents in Wave 1 of the LASI (2017–2018). Weighted descriptive statistics and multivariable logistic regression models assessed associations between CLD and CHD, incorporating interaction terms for key health risk factors. Mediation analysis used the Karlson–Holm–Breen method to decompose total effects into direct and indirect effects. The prevalence of CHD and CLD was 3.86% and 7.29%, respectively. Females with CLD had higher odds of CHD (AOR=2.89) than males. Significant interaction effect modifications were observed for SRH, hypertension, high BMI, diabetes, cancer, stroke, and high cholesterol, predominantly among females. Mediation decomposition analysis identified SRH as the strongest mediator, explaining 34% of the observed CLD–CHD association overall (52% in males, 24% in females), followed by hypertension (10%) and high cholesterol (5%). CLD and CHD are more prevalent among middle-aged and older adults in India, with co-occurrence influenced by age, multimorbidity, obesity, poor SRH and cardiometabolic conditions. Gender differences and geographic variation underscore the need for tailored strategies. Recognising CLD–CHD coexistence can inform comprehensive geriatric assessment, risk stratification and coordinated care, while population-level interventions should integrate lifestyle promotion, multimorbidity management and gender-sensitive approaches.