Association Between Emphysema and Coronary Artery Calcium on Low-Dose CT in Urban Chinese Adults: Does Lifestyle Matter?

<b>Background and Objectives</b>: Emphysema and coronary artery calcium (CAC) share common lifestyle-related risk factors, yet their association in Chinese populations remains understudied. This study investigated how lifestyle factors influence the association between emphysema and CAC score in an urban Chinese general population. <b>Methods</b>: The study included 1000 participants from the Chinese Nelcin-B3 urban general population study originating in 2017 who underwent low-dose CT (LDCT) screening and comprehensive CT assessment. Emphysema was visually assessed by subtype and severity. CAC was measured using the Agatston method and categorized as 0, 1-100, and >100. Questionnaire-based lifestyle factors (smoking, BMI, diet, physical activity, alcohol consumption and environmental exposures) were categorized based on number of unfavorable behaviors. Multivariable multinomial logistic regression adjusted for age, sex, education and cardiovascular risk factors examined the associations between emphysema and CAC, with interactions and stratified analyses for lifestyle effects. <b>Results</b>: Emphysema was present in 62.3% of the participants, with centrilobular being the most common subtype (61.5%). Paraseptal emphysema was associated with both CAC 1-100 (OR: 2.07 [1.03-4.15]) and CAC > 100 (OR: 2.94 [1.26-6.84]). Severe emphysema was linked to CAC > 100 (OR: 3.50 [1.38-8.84]). These associations were stronger in the intermediate unhealthy lifestyle group for paraseptal (OR: 5.41 [1.70-17.22] and moderate and severe emphysema (OR: 9.64 [1.64-56.55]; OR: 3.73 [1.07-13.06]), respectively, but not significantly different. <b>Conclusions</b>: While paraseptal and severe emphysema are associated with higher CAC scores, there is no modifying effect of lifestyle factors. These findings suggest that cardiovascular risk assessment could be of importance in individuals with emphysema. Further longitudinal studies are needed to clarify the clinical implications.