Risk of incident stroke and heart disease subtypes in a nationwide cohort of Korean radiation workers.

Abstract

Previous studies have explored the association between low-dose radiation and circulatory diseases, but few have focused on stroke and heart disease subtypes. This study aimed to investigate subtype-specific risks among Korean radiation workers. We analyzed data from 186 233 workers enrolled in the Korean Radiation Workers Study cohort. Individual radiation exposure was assessed using personal dose data, and organ-specific doses were reconstructed. Using the National Health Insurance Database, circulatory diseases were identified based on validated operational definitions developed for six subtypes. Sex- and age-standardized incidence ratios (SIR) were estimated. Dose-response relationships were assessed by estimating the relative rates (RR) and excess relative risks (ERR) per 10 mGy, adjusting for the sex, attained age, birth year and calendar year. Additional confounders in the ERR models included income level, smoking, blood pressure, blood glucose level, and body mass index. Ischemic heart disease has the highest incidence (367.6 per 100 000 person-years), followed by heart failure and ischemic stroke. The overall incidence rates of most subtypes were lower among radiation workers than the general population, reflecting a healthy worker effect (SIR range: 0.70-0.90). No statistically significant positive dose-response relationships were observed for all six subtypes; ERR estimates were generally negative, with the highest point estimate observed for hemorrhagic stroke (ERR per 10 mGy: 0.014; 95% confidence interval -0.049-0.077). While no clear radiation-related risk was observed, the findings highlight the importance of subtype-specific analysis and the need for refined outcome definitions and longer follow-up periods to clarify potential low-dose radiation effects.