On the plus side, the story makes it clear that we don’t know if sauna use — or some other factor associated with sauna use — is responsible for the benefits observed in the study. But it would have been stronger had it quantified the potential benefits in absolute terms, and put a bit more emphasis on the costs and availability of saunas in the U.S.
The study being reported on shows that Finnish men who take multiple saunas per week seem to suffer less heart disease than those who take only one per week. There are plausible biological reasons to believe that saunas are beneficial. But frequent sauna users may also be different from those who sauna less frequently in important ways that affect their risk. Economics, social support and other factors may also be at work — as one expert says in the story itself.
For most Americans, access to a sauna would require membership in a health club or community center swimming pool, which is out of reach for many families. The story could have easily mentioned cost.
The story included the size of the study (2,315) and identified two different levels of risk reduction for fatal heart disease: One of 23% for men who took a sauna two or three times a week, and a 48% reduction for those hitting the dry heat four to seven times per week. But we’d note that these percentages are comparisons relative to men who took saunas once a week, and the story doesn’t provide any sense of how often those men died from heart disease. Therefore, we don’t know if the reductions for the other groups represent large, clinically important decreases, or just a marginal lowering of an already-low number. To avoid such conundrums, we always encourage stories to report the absolute risk reduction whenever possible. And in this case, information about absolute risk for the three groups was provided in the study abstract. The study tells us that the rates of fatal coronary heart disease were 14.9% in the once a week group, 11.5% in the 2-3 times per week group, and 8.5% in the 4-7 times per week group. We offer a primer on this topic here.
The story squeaked by on this one by pointing out that there are some sudden deaths associated with sauna use, usually in relation to alcohol use. But the story also mentions that previous studies have suggested that sauna bathing might have some harmful effects. We wonder what those effects were, and why we should trust the new study’s assurance that there are no such effects.
The story included more than one statement by scientists saying essentially “We don’t understand” the results, and that additional study is needed. We want to praise this transparency, as it’s certainly true that this study can’t establish that saunas cause the health benefits that were observed. In fact, we would have liked much more information about why confounding variables might muddy the conclusion. Men who have the leisure time and social connections to take a sauna more often may have other reasons for good health besides the heated 14 minutes they spend during an average visit.
There was no disease mongering.
The story references a written editorial published to accompany the story in JAMA, which we’ll consider good enough for a satisfactory rating here. Actually interviewing someone not affiliated with the research might have yielded additional interesting insight on this topic.
The story does not provide any context for the research, in terms of other habits that are known to reduce cardiovascular risk. These include: regular exercise, healthy eating habits and maintaining a healthy weight – among others.
In Finland, saunas are common. Since this story was published for a US audience, it should have included some mention of the relative abundance or scarcity of saunas here and where to find them. The story warned that the same benefits shouldn’t be expected from hot tubs and steam rooms — a nice addition. As we mentioned above, the cost of access to sauna would have been a great addition to the story.
The story mentioned that the results of this study were not novel and built on existing research.
The story may have relied to some extent on a news release, but it clearly wasn’t the only source material. The quote from Dr. Redberg appears in the release as well as in an online editor’s note. Other comments and data come from the published study and weren’t in the news release. Although no interviews appear to have been done — something which would have eliminated any doubt — it seems clear enough to us that the story went beyond the release.