Workplace size and cardiovascular disease subtypes among 11 million Korean wage workers: a nationwide cross-sectional...

Cardiovascular disease (CVD) encompasses distinct conditions whose risk factor profiles and socioeconomic gradients diverge. Workplace size is an administrative marker related to regulatory protections, health service access, and working conditions, but population-based evidence on whether CVD prevalence differs by subtype across workplace-size categories is limited. We examined the association between workplace size and the prevalence of 10 CVD subtypes among Korean wage workers.

This nationwide cross-sectional study included 11,212,512 Korean wage workers from the National Health Insurance Service database (2021). CVD cases were identified across 10 ICD-10 subtypes (I00-I99; three or more claims). Workplace size was classified into eight categories aligned with regulatory thresholds under the Korean Occupational Safety and Health Act. Logistic regression estimated adjusted odds ratios (aORs), controlling for sex and age, with the 5-29-worker category as reference. Sensitivity analyses applied hospitalization-based case definitions.

Crude hypertensive disease (I10-I15) prevalence was highest in one-person workplaces (11,273.5 per 100,000), but after age and sex adjustment the crude OR of 1.12 changed direction to an aOR of 0.85 (95% CI 0.83-0.87). Mid-range workplaces (30-999 workers) showed the highest hypertensive disease aORs (up to 1.09). In contrast, ischemic heart disease (IHD; I20-I25) aORs were modestly elevated in the smallest workplaces (one-person: 1.12, 95% CI 1.05-1.19; 2-4-person: 1.05, 1.03-1.08), and cerebrovascular diseases (I60-I69) showed a modestly elevated aOR in the largest workplaces (1000 or more: 1.06, 1.03-1.08). Hospitalization-based sensitivity analyses showed IHD crude ORs remaining elevated and strengthening under more stringent criteria.

The association between workplace size and CVD prevalence was heterogeneous across subtypes. Hypertensive disease showed the highest adjusted prevalence in mid-range workplaces, a pattern consistent with demographic composition differences, whereas IHD and cerebrovascular diseases showed divergent prevalence patterns across workplace sizes. These findings indicate that the relationship between workplace size and CVD prevalence varies by subtype, with no uniform pattern across all workplace-size categories, and support disease-specific approaches to workplace-based cardiovascular surveillance. Because adjustment was limited to age and sex, these associations should be interpreted as descriptive prevalence patterns rather than causal effects.