Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study.
Level 3 - non-randomized controlled study
Prospective non-randomized cohort study with long-term follow-up.
PubMed 29720543 · doi:10.1212/WNL.0000000000005606
What was done
Baseline sauna bathing habits were assessed in 1,628 Finnish men and women aged 53-74 years (mean age 62.7 years) without prior stroke from the Kuopio Ischemic Heart Disease prospective cohort study. Participants were grouped into 1, 2-3, and 4-7 sauna sessions per week. Multivariable hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated for incident stroke across a median follow-up of 14.9 years, adjusting for age, sex, cardiovascular risk factors, physical activity, and socioeconomic status.
What was found
During 14.9 years of median follow-up, 155 incident stroke events occurred. Compared with 1 session per week, participants bathing 4-7 times per week had an age- and sex-adjusted HR for stroke of 0.39 (95% CI 0.18-0.83). After full adjustment for cardiovascular risk factors, physical activity, and socioeconomic status, the HR was 0.38 (95% CI 0.18-0.81). No interaction was observed across age, sex, or other clinical subgroups (all p > 0.10). The association was similar for ischemic stroke but modest for hemorrhagic stroke (n = 34 events).
Why it matters
This study provides prospective evidence that frequent sauna bathing is strongly and independently associated with a lower incidence of stroke in middle-aged and older adults.
Limits
Sauna frequency was assessed only at baseline and may have changed over time. The cohort was restricted to a single Finnish region, limiting generalizability to other populations and sauna cultures. The observational design cannot eliminate residual confounding, and the low number of hemorrhagic strokes (n = 34) reduced power for subtype-specific analyses.
Cited by
- supports Sauna use 2 to 3 times per week reduces stroke risk by 14%, and 4 to 7 times per week reduces stroke risk by 61% in men and women compared to once per week.