Prediagnostic smoking intensity trajectories and subtype-specific vascular disease risk in a nationwide health screening population

Objectives We examined associations between prediagnostic smoking trajectories and subtype-specific vascular outcomes. Methods Using the National Health Insurance Service Customized Database, we conducted a matched case-control study of 1,106,228 adults in South Korea. The exposure was prediagnostic smoking trajectory group, and the outcomes were cardiovascular and cerebrovascular disease and five subtypes: ischemic heart disease, acute myocardial infarction, cerebrovascular disease, intracranial hemorrhage, and cerebral infarction. Trajectories were identified using group-based trajectory modeling, and conditional logistic regression estimated odds ratios. Results Trajectory modeling differentiated never, former, high-decreasing, moderate-stable, and high-stable smoking histories. Overall odds increased with smoking intensity and persistence, from former smoking (OR 1.11) to high-stable smoking (OR 1.97). The high-decreasing group showed lower odds than the moderate-stable and high-stable groups. The strongest associations were observed for acute myocardial infarction (OR 3.51) and cerebral infarction (OR 2.46). Conclusion Prediagnostic smoking trajectories revealed a graded vascular risk pattern shaped by intensity, persistence, and reduction, with the greatest excess risks for ischemic outcomes. Repeated smoking histories in screening data may move risk assessment beyond current smoking status and inform earlier cessation intervention.