A large retrospective observational study was conducted to see if encouraging patients to elect tranexamic acid (TXA) therapy in joint replacement surgery was associated with a reduction in costly blood transfusions. Based on this observational study, the story has unfortunately drawn certain conclusions as if the study were a prospective randomized trial and able to prove cause and effect — namely the conclusion that TXA therapy “reduces” blood transfusions. Though we commend the article for exploring the lower-cost alternative of TXA therapy and for consulting several independent sources, the coverage would’ve greatly benefited from a better understanding of the limitations underlying the study. While TXA was “associated with” a reduction in blood transfusions, it is inappropriate to state that the drug “reduced” blood transfusions. There are also some head-scratching links given in the article. For instance, a link on the use of TXA in slowing blood loss among soldiers injured in combat directs to a webpage on the mental health of soldiers.
Blood transfusions, though generally safe, are quite expensive when they are required in joint replacement surgery. TXA could be a low-cost alternative for eligible patients undergoing the procedure.
The piece does a good job of highlighting the low-cost advantage of TXA over blood transfusions. An expert independent from the original study, Dr. Donald Jenkins, is seen providing estimates of the respective costs.
The article breaks our rule of citing only relative, rather than absolute, risk reduction numbers. An idea of the baseline transfusion rate, which is given in the study, could have been juxtaposed with these numbers. While the reported 40% drop in the rate of blood transfusion (incorrectly attributed to the administration of TXA, see comment below under the Quality of Evidence criterion) sounds impressive, the two numbers constituting this calculation are 8.8% and 5.2%, the change in rate of blood transfusions pre and post protocol, or a 3.6% absolute change.
The story mentions that there are risks associated with the drug, including “the formation of a blood clot in a vein deep in the body, or deep vein thrombosis, to heart attack,” so we’ll rate the story Satisfactory. It also refers to the existence of a previous research study on the low complication rate of TXA used during joint replacement procedures. But this reference is vague, and the story doesn’t provide quantitative estimates of the supposedly low complication rate. There is also no discussion from doctors who don’t use TXA as to their reservations with its use or general discussion about risks of the drug. The patient population that generally receives total joint replacements is elderly, so many patients can have many cardiovascular risk factors.
The article has missed the critical point that the underlying study being reported on is observational in nature and can’t prove cause and effect. Therefore, claiming that TXA “reduced the rate of blood transfusion” is inappropriate. The researchers studied what happened before and after the introduction of a protocol that encouraged the use of TXA for hip or knee arthroplasty in eligible patients, i.e. those deemed to be at low risk of certain conditions. The primary outcome of the study is the proportion of patients receiving a blood transfusion before, during, or after surgery. A significant difference was found between a group of patients before the protocol was implemented and another group after it was implemented. But the key thing to realize is that even in the pre-protocol group, there were patients who elected to receive TXA. In other words, the study does not compare TXA versus lack of TXA. Instead, the study compares a protocol that advocates the use of TXA and one that did not encourage (nor discourage) the adoption of TXA. In either case, the patients ultimately decide if they want TXA or not. Naturally, if the subjects themselves are allowed to choose if they receive a treatment, the conclusions that can be drawn on treatment effect need to be made with extra caution.
We’re concerned that the article’s leading paragraph suggests that the use or lack of use of TXA could almost amount to a quality indicator that patients should use when selecting their doctor or hospital. This is despite the fact that the drug is not made for every patient, and also has a serious risk profile in the wrong patients. But that’s more treatment-mongering than disease-mongering, so we’ll award a Satisfactory here.
Nice job here. Two independent sources are interviewed, Dr. Donald Jenkins and Dr. Bush-Joseph.
The article makes a reasonable effort to compare TXA therapy to the alternative of not receiving TXA during joint replacement surgery. We wish the story had gone further with its discussion of which approach is riskier–TXA or blood transfusion.
The story correctly advises patients interested in TXA to broach the subject with clinicians handling their care, who can assess whether the drug is appropriate for their individual situation.
The original study points out that many randomized trials, 33 specifically (of which 24 were double-blinded), have been conducted to examine the utilization of TXA therapy in hip or knee surgery. Thus the study reported in this article is certainly not novel in terms of studying the efficacy of TXA in joint replacement surgery. The novelty lies more in the size of this retrospective observational study compared to the limited sample size, and thus power, of previous randomized controlled trials.
The study does not seem to be solely based on a news release.
Systematic, Criteria-Driven
Monday at #ADA2021, an infectious disease epidemiologist, a journalist, and a researcher shared perspectives on communication of risk in the era of COVID-19: http://ow.ly/ROfR30rMeE7 @AstleyCM @garyschwitzer @berthahidalgo @ADA_DiabetesPro
Shoutouts to @susan_bewley @drkevinknopf @MichaelBaum11 in this call for more than fawning coverage from press releases for these kinds of stories.
Also, linked history inside goes back 5 years just on Grail apparently trying to become Holy Grail. https://twitter.com/garyschwitzer/status/1408849696416841731
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