It simply isn’t good enough to report on a new test being “more predictive” or “more sensitive” without giving actual data. How much more predictive? How much more sensitive? Why should readers care?
Diagnosing a heart attack in the emergency room is as much of an art form as it is a science. Only a minority of people suspected of having one are actually diagnosed using a combined approach of a medical history, an electrocardiogram, a physical examination and finally laboratory tests. As our understanding of various blood markers improves, our tests have become more specific and the ability to correctly diagnose patients in a shorter period of time has improved. The use of a more specific maker of heart muscle injury and heart attack is important. As independent physicians quoted in the story explain, a more sensitive test could save a lot of money, could help with many emergency decisions and treatment, and may result in improved outcomes. Because of significant gaps in important details, this story misrepresents what the authors of the study concluded.
There is no discussion of cost – not of the new troponin I test nor of any existing test.
Explaining sensitivity, specificity and negative predictive value is admittedly a task in and of itself. But the difficulty in explaining the concepts and applying them to the results of a study does not exempt a story from trying. The story only referred to the new test being “more predictive than other biomarkers” or “more sensitive than the existing one.” But even those relative references weren’t quantified. No sense of the scale of improvement of was provided. That’s not helpful.
Since the sensitivity and specificity of the new test was not quantified, the story provided only a glowing report of progress – of benefit. There was no discussion of potential harms.
Most physicians and most organizations would frown on making a diagnosis of a heart attack based simply on a blood test. Up To Date, an authoritative resource suggests that patients with a suspicion of having a heart attack have an electrocardiogram, undergo a brief medical history, have a physical examination and have blood drawn for biologic markers. The story suggests that this new blood test can be used alone to make the diagnosis or rule it out. Exaggerating the benefits of a test without placing it into the context provides the readers with a false impression of the test and its utility. Making decisions on the basis of a single blood test could lead to patient harm.
There was no critical analysis of the quality of the evidence. The story didn’t even include the following limitations provided by the researchers in the journal article:
Our study had several limitations. First, the final diagnosis of acute MI was based substantially on in-house troponin measurements, which might bias the biomarker evaluation toward troponin assays. Because both the index test and reference standard included a change in troponin levels over time, there is the potential for a type of incorporation bias, which may overestimate the measure of diagnostic accuracy of serial hsTnI levels. However, hsTnI appeared to facilitate identification of patients with non–ST-elevation ACS, a diagnosis independent of troponin values. Second, the number of patients with availability of biomarker values differed, which potentially could affect the results. Third, the proportion of patients with MI was rather high compared with that of other studies involving consecutive patients with chest pain, but the number is in line with different European cohorts.Still, this and the fact that only white European patients were enrolled might limit the generalizability of the findings to other populations.
There was no disease mongering.
The story mentioned that the study was funded by two pharma companies but it did not include any of the individual disclosures included in the journal article itself.
And, in terms of sourcing, while the story did include quotes from two independent physicians, neither of them directly addressed the quality of the evidence.
One said “we can rule out heart attacks more quickly with the new test” but it wasn’t clear if she had used the test or if she was commenting on the data reported. So we don’t know why she was used as a source.
The other spoke in only very general terms about the ultimate goal of such research and about the need for such a blood test – but nothing about the evidence itself.
The only comparisons are very broad and lack substantiation with actual data. The study compared the existing test for troponin l and a more specific test and examined the data using different break points and time. Here’s the authors conclusions, “Among patients with suspected acute coronary syndrome, hsTnl (the new test) or cTnl (the existing test) determination 3 hours after admission may facilitate early rule out of MI (heart attack). A serial change in hsTnl or cTnl levels form admission (using the 99th percentile cut off value) to 3 hours after admission may facilitate early diagnosis of AMI.” The story conclusions don’t seem to match those of the authors.
The availability of the new test is left as a mystery by this story.
Is it experimental?
Is it growing in use already?
Is it in widespread use?
We’re not told a thing about its availability or use.
We’ll give the story the benefit of the doubt on this one for trying to establish the relative novelty of this troponin I test but how it is novel or superior – as already outlined – is not adequately addressed.
There’s no evidence that the story relied solely or largely on a news release.