Michael Joyce is a writer-producer with HealthNewsReview.org and tweets as @mlmjoyce
Study abstracts presented at these meetings are often pitched as urgent or a ‘breakthrough’, when actually they’re usually preliminary and yet to be rigorously scrutinized by others.
Headlines like these popping up in the coverage of this week’s Alzheimer’s Association International Conference (AAIC) in Chicago are a striking case in point:
The research that generated these headlines comes from an extension of the SPRINT study — called Sprint MIND — that looked into whether more aggressive lowering of blood pressure affects “Mild Cognitive Impairment” (MCI) which is defined in small/italic print at the end of the AAIC news release as:
MCI causes a slight but noticeable and measurable decline in cognitive abilities, including memory and thinking skills, but the changes are not severe enough to interfere with daily life or independent function. A person with MCI is at an increased risk of developing Alzheimer’s or another dementia. However, MCI does not always lead to dementia. In some people, MCI reverts to normal cognition or remains stable.
None of the news stories we reviewed told readers how MCI was measured or defined in the study. Richard Hoffman MD, MPH, director of the Division of General Internal Medicine for the University of Iowa Carver College of Medicine, considers this important information.
“It’s mentioned that subjects completed ‘at least one follow-up cognitive assessment.’ But I’d want to know what was the protocol for following cognitive impairment — not just the type and timing of the assessments, but was the follow-up comparable for both groups.”
Any disparity in how those assessments were carried out could imbalance the study outcomes. But that’s not the kind of detailed information that readers can glean from a study abstract presented at a meeting.
Another major deficiency with many news stories is that they erroneously equate MCI with dementia (see Bloomberg and TIME headlines above).
In fact, the study authors looked for, but didn’t find, a statistically significant reduction in the rate of dementia among those treated with more aggressive blood pressure lowering. While it’s possible that such a benefit could emerge as the participants continue to be followed, it’s entirely speculative and misleading to suggest that this outcome has already been documented.
Kenny Lin MD, MPH, is a professor of family medicine at Georgetown University. Like Hoffman, he wanted to know more about the cognitive assessments. But he also expressed another concern.
“There’s no mention of previous trials (here and here) on the effect of lowering blood pressure on dementia prevention which showed mixed results or no benefit of antihypertensive medication on the development of dementia.”
Most of the news coverage reported the study’s major finding as this: Of the over 9,000 adults with increased cardiovascular risk (but no known diabetes, dementia, or stroke), those randomized to receive more intensive blood pressure treatment (blood pressure goal ≤ 120 mm mercury) were ‘19% less likely to develop MCI’ than those with more relaxed blood pressure goals (≤140 mm mercury).
That’s a relative risk reduction, which often serves to exaggerate the size of the actual benefit.
The absolute risk reduction was not reported in the study abstract, but the Wall Street Journal — which apparently dug deeper than anyone else for those numbers — reported it as just over one percentage point:
“Researchers found that 285 participants receiving intensive blood-pressure treatment, or 6.1% of the group, developed mild cognitive impairment, versus 348, or 7.4%, in the standard treatment group.”
We’re left wondering what the difference is between a 19% improvement and an improvement of 1 percentage point, and that’s something the news release from the Alzheimer’s Association should have made clear.
Also very troubling is the fact that, although the Alzheimer’s Association news release DID provide detailed information about adverse consequences from aggressively lowering blood pressure, none of the news coverage we came across did so. We’ve encountered omissions like this before in our extensive coverage of the SPRINT study, whose findings were initially reported as a slam dunk that would immediately change practice. Only later did details emerge that would make many clinicians question the validity of the findings and their relevance to broad swaths of patients.
“The original SPRINT trial generated a robust discussion amongst clinicians regarding how low is too low, especially for older patients,” said Preeti Malani, MD, a professor of medicine at the University of Michigan.
“The decisions regarding a blood pressure goal are very nuanced and individualized. While appropriate treatment of high blood pressure is one of the most important clinical interventions that can be made for patients, decreasing dementia risk is probably not what drives the calculus around lower blood pressure goals. So although the MCI data from this study may be encouraging, I’d like to see something more definitive before calling this an effective means to ‘stave off dementia.’ That’s overstated based on this abstract.”
Right now we’re about 24 hours into the coverage of this meeting abstract that has yet to be published in a peer-reviewed journal. Dozens of news stories have already been circulated but crucial details are missing. We recommend, at the very least, paying attention to the following.
Go beyond a single source — much of the coverage only quotes the lead author. Most often the quotes are glowing and not balanced by independent sources that ought to be used to confirm or refute findings.
Check the hyperbole — glowing quotes by lead authors are often major sources of unjustified or hyperbolic language. The lead author of this research was quoted by Bloomberg (above link) as saying this about aggressive blood pressure treatment: “It may give another five or 10 years with a healthy brain.” That’s based on speculation, not data.
“Preliminary & Unpublished” — kudos to the Associated Press who had this to say about the study results: “They’re considered preliminary until published, expected later this year.”
Look beyond the meeting — as mentioned by Dr. Lin above, there are often existing published studies available that address the same topic. Not infrequently, the findings may be quite different. Giving readers that information empowers them to better weigh harms and benefits.
There is something about embargoed news releases coming from medical meetings that triggers an unhelpful sense of urgency amongst healthcare reporters.
Very, very rarely do such abstracts contain breakthroughs, paradigm shifts, or unassailable information that will immediately change patient care. And even if they did, isn’t that exactly the kind of information reporters would want to take more time with?
Here’s more of our coverage of the 2018 Alzheimer’s Association International Conference:
We also appreciated this coverage of the Sprint MIND trial by Larry Husten of Cardiobrief: