Overview
- Analysis of 9,295,979 Korean adults found that starting to smoke before 20 independently raised long-term risks of myocardial infarction, stroke, and all-cause mortality.
- Early heavy starters had markedly higher hazards versus nonsmokers, including HR 2.43 for heart attack, HR 1.78 for stroke, HR 2.00 for combined events, and HR 1.82 for death.
- The study showed a dose–response interaction in which earlier initiation magnified the harmful effects of greater cumulative smoking exposure.
- Researchers used baseline health screenings from 2009 with follow-up through 2018 and adjusted for demographics, clinical factors, and socioeconomic variables.
- Authors note limitations such as self-reported smoking histories, potential recall and unmeasured confounding, limited follow-up duration, and a predominantly male Asian cohort that may constrain generalizability.