Is one’s health helped or hurt by being in a hot sauna? Researchers from Finland conducted a study to find out, with results recently published in a top-flight medical journal.
In the study, data came from 2,315 men who used saunas. And what were the study’s findings? Those who had saunas more often each week, and those who stayed longer in the sauna, had, over time, fewer fatal heart attacks.
Why did this study get published in a prestigious scientific journal? One of the reasons was this: the researchers used complex statistical procedures to examine the relationship between sauna use and heart attacks while controlling for things such as age, BP, tobacco use, SES, physical activity, etc.
Here is a list of the intermediate and advanced statistical procedures used by the researchers: (1) a chi square test, (2) analysis of variance, (3) 95% confidence intervals, (4) a multivariate Cox model with several covariates (age, BMI, systolic blood pressure, cholesterol levels, smoking, alcohol consumption, previous myocardial infarction, diabetes, cardiorespiratory fitness, resting heart rate, physical activity, and socioeconomic status), (5) sensitivity analyses, (6) survival ratios using the Kaplan-Meier method, (7) hazard ratios and cumulative hazard curves, (8) plots of Schoenfeld residuals to check the proportional hazards assumption, and (9) Martingale residuals to check the linearity assumption.
The research report was published on February 23, 2015, in the Journal of the American Medical Association: Internal Medicine. It had this title: “Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events.” The author/researchers were Tanjaniina Laukkanen, Hassan Khan, Francesco Zaccardi, and Jari A. Laukkanen.