This story about the risk of blood clots linked to the cancer drug Avastin does a decent job of conveying the key findings. But it suffers from at least one significant flaw.
On the positive side, the story explains the findings in a clear and fair way, with adequate detail, sourcing and context. The story is based on a credible study on a topic relevant to many readers. The reporter follows several practices of good medical reporting, as the ratings show.
Having said that, reporting the increased risk as 30 percent rather than 33 percent is an inexplicable, fundamental error.
There are two additional problems, however.
1. Some reporting at the end of the story takes up the question of total benefit and total risk for patients who take Avastin, but this could have been explored further. The bottom line most patients and physicians care about isn’t the risk of one side effect. It’s whether taking the drug improves survival.
It’s true the meta-analysis did not take up that question. But the story could have explored this matter more thoroughly on the readers’ behalf, and would have put that reporting more at the core of the story, not as going-away thoughts at the end.
2. The report fails to distinguish the differences in risk among the different types of cancer for which Avastin is used. The study itself included this information, and it is important for the reader to know. This is a significant omission.
The article reports that Avastin costs up to $55,000 per year.
The reporter does a decent job of describing the results, reporting that 12 percent of Avastin patients in the study developed blood clots, a "30" percent higher risk than those who did not take Avastin. This formulation, which appears in the abstract of the study, provides both absolute and relative risks.
But ideally the report would have provided a more apples-to-apples comparison of absolute risk, stating that 12 percent of Avastin patients developed blood clots, compared to 8 percent of controls.
The story earns an unsatisfactory rating, though, because it reports the findings incorrectly. The study shows the risk linked to Avastin to be 33 percent greater, not 30 percent.
Further, the story fails to indicate the differences in risk for different types of cancers, which vary considerably. This is a significant omission.
The story exaggerates the risks associated with the use of Avastin. The opening lines note the seriousness of the clots. The study notes a 12% incidence of venous clots in patients treated with Avastin–yet fails to note that only about half required treatment.
This leaves the reader with an incorrect belief about the true risk. By overstating the risks of serious blood clot, the story could leave patients who may benefit from treatment with an inaccurate impression of risk vs. benefit.
The article is based on an analysis of previous research published in The Journal of the American Medical Association.
The study author is quoted saying the results are more powerful than individual studies because it takes into account the results of 15 high-quality papers involving almost 8,000 patients.
The story might have added that results of meta-analyses are often criticized, and rarely considered definitive, because they combine data from studies that used different methologies. This failure is significant in that it may add an undue degree of importance to the analysis.
The article doesn’t exaggerate the severity or prevalence of the cancers Avastin treats.
The story cites the study itself, the lead author, a company spokesperson, and one independent clinician.
This is adequate sourcing for a story of this length.
The story mentions, at least briefly, that Avastin treats cancer via a different mechanism from traditional chemotherapies.
But the story falls short of a satisfactory rating by mentioning, only at the end and very briefly, that most Avastin patients also use conventional chemotherapy–and are therefore exposed to all of those side effects as well.
This raises, but doesn’t answer, the fundamental question of the overall benefit and overall risk of adding Avastin to treatment. A reader exits the story with an unsettling piece of information that should have been put in context earlier.
The article makes clear that Avastin is widely available to and used by cancer patients.
The story explained the relative new-ness of the drug.
With several sources used, it’s a safe bet this story didn’t rely largely on a news release.
Systematic, Criteria-Driven
The tale of two “negative” studies. Or, how spin is applied to make research findings look more impressive. A must read. https://johnmandrola.substack.com/p/the-tale-of-two-negative-studies
The @nytimes chose to interview one of the editors of the @AnnalsofIM (publisher of this paper) who "gushed with extraordinary glee: It’s huge! There are very few things that reduce your mortality by 30%."
Turns out coffee is not one of those few things despite all that glee. https://twitter.com/garyschwitzer/status/1533202075928215558
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