This CNN story describes yet another observational study of the possible links between coffee consumption and health, this one concluding that overall, whether decaf or regular, coffee drinking is linked to reduced risk of death from heart disease, diabetes, and neurological disorders such as Parkinson’s Disease, although not cancer. The headline — “Coffee could literally be a lifesaver” — is overblown given the types of evidence we’re talking about. But the story otherwise does a worthy and responsible job of framing the study’s weaknesses and strengths, particularly so in explaining confounding factors and why so many coffee studies historically have yielded “murky” results. It also takes a pretty good stab at exploring the study’s suggestion that natural chemicals in the coffee may be responsible for the beverage’s potential health benefits, an effort that was essentially missing from a story in STAT that was otherwise much stronger in describing the strengths and weaknesses of this and all observational studies. The CNN story also aptly noted the novel analysis of coffee drinking in a non-smoking subset of the nearly 200,000 subjects. Overall, this CNN piece could have been made stronger by having outside experts comment on the findings, as the STAT piece did to excellent effect; by offering more qualitative details about the sources of the data; by noting that in excessive quantities, the new study identified a slight increase in risk of death; and — as the STAT piece did superbly, noting the likely “benefits” in terms of absolute risk (very, very small).
Readers and viewers of mass media have been nearly whiplashed by claims and counterclaims related to the benefits and risks of coffee drinking. A few studies over the past several decades have concluded that, at least in large amounts, coffee can be “toxic,” but most of the coverage has focused on the drink’s possible health benefits, but in ways that led to substantial confusion. The new analysis, described in the American Heart Association journal Circulation, has some significant statistical assets not present in previous studies, including a subset analysis of non-smokers’ death risks. Its central finding — that coffee safely confers health benefits (essentially reduced death risks for some major categories of disease) even in relatively high doses among non-smokers — is likely to be reassuring to coffee addicts — and their physicians.
Arguably, most people know how much their java habit costs them every day, and neither this CNN story, nor the more detailed and “news you can use”-focused STAT story mentioned costs. Like hazelnut cream, some mention of the overall cost of the coffee habit in the U.S. would have added some flavor, but this omission gets a pass.
CNN’s piece earns a ding for not mentioning the small risk of deaths overall in the whole study cohort among those who drank excessive amounts of coffee; and also one for not — as a STAT article did — noting the decreased death risk in absolute terms. We only learn of the benefits in relative terms, which can be misleading. The story does get some credit for noting the data on possible links of coffee drinking and suicide rates and why the data suggest that chemicals in the coffee itself may confer any benefits seen from coffee drinking. On balance, however, there wasn’t quite enough here to earn a “satisfactory” rating.
As noted earlier, the CNN piece should and could have noted the slightly increased risk of death is those participants in the current study who drank very high amounts of coffee, something the STAT article covering the same research did mention to good effect and in context.
The CNN story could have been much stronger and more credible if it had noted — as the STAT story did — that the data used in the new analysis came from three major, continuing, federally funded studies of nurses, physicians and other health professionals. Such information is not incidental, given that these large-scale epidemiological research projects have had their successes and failures, but mostly because health care professionals may have particular lifestyles and knowledge that the general population does not, differences that may have an impact on the findings. The story also stumbles when it says that “drinking coffee, whether regular or decaf, could reduce the risk of death.” Since this was an observational study incapable of proving cause and effect, this overstates the findings. The CNN story did a good job of qualifying the findings but these missteps, along with the absence of outside commentary, are significant weaknesses.
Not a one, and too bad, really, because such stories — of they are going to reduce or limit confusion — need expert sources for context and consumer guidance, something the STAT story gave readers tied up in red ribbon.
We thought that a comparison of alternatives to coffee was beyond the scope of the story.
Coffee is widely available, and that’s obvious from the story.
The CNN story did a good job of pointing out what was new in this observational study and why it mattered. The STAT story noted how “clever” the researchers were in approaching the analysis of the non-smoking sub-set, which also emphasized the novelty of this study.
There was a news release issued by the American Heart Association, which quoted both the doctoral candidate in the CNN story and the senior author. The CNN story appears to have been based at least in part on an interview with the former.