Joint associations of lung function of both general and abdominal obesity with cardiometabolic multimorbidity: a cross-sectional study

Background Cardiometabolic multimorbidity (CMM) has become an escalating public health challenge amid global population aging. Although lung function has been implicated in individual cardiometabolic conditions, its role in predicting CMM, particularly in relation to obesity, remains poorly characterized. This study aimed to evaluate the associations between lung function indicators and CMM, and to explore their joint associations with general and abdominal obesity. Methods This cross-sectional study included 35,414 community-dwelling adults aged ≥65 years from the Zhejiang Provincial Chronic Obstructive Lung Disease Screening in Jinhua City, China. Lung function was assessed by standardized spirometry. Participants were classified as having preserved lung function or restrictive spirometry (FEV₁/FVC ≥ 0.70 with FVC%predicted 80%). General obesity was defined as BMI ≥ 28.0 kg/m 2 , and abdominal obesity as waist circumference ≥90 cm (men) or ≥85 cm (women). CMM was defined as coexistence of ≥2 conditions: type 2 diabetes, coronary heart disease, or stroke. Multivariable logistic regression models examined associations of lung function and obesity with CMM, adjusting for demographic, lifestyle, and clinical factors. Joint effects and dose–response relationships were assessed. Results CMM prevalence was 1.02%. In fully adjusted models, higher lung function was inversely associated with CMM. Compared to the lowest quartile, the highest quartile had significantly lower CMM odds for FVC%predicted (OR = 0.60, 95%CI: 0.44, 0.81), FEV₁%predicted (OR = 0.71, 95%CI: 0.53, 0.95), and PEF%predicted (OR = 0.64, 95%CI: 0.47, 0.86). Restrictive spirometry was associated with 56% higher CMM odds versus preserved lung function. Both general obesity (OR = 1.30 per SD, 95%CI: 1.18, 1.43) and abdominal obesity (OR = 1.33 per SD, 95%CI: 1.21, 1.45) significantly increased CMM odds. Joint analysis showed participants with restrictive spirometry and abdominal obesity had the highest CMM, while those with preserved lung function and normal abdominal circumference had 65% lower odds (OR = 0.35, 95%CI: 0.25, 0.49). Conclusion These findings suggest that reduced lung function in combination with obesity represents a high-risk phenotype that is more strongly associated with CMM. Simultaneous screening of lung function and obesity status may help identify older adults at greatest risk for CMM. However, longitudinal studies are warranted to confirm the temporality of these associations.