STAT readers on diagnostic tests, marijuana regulation, and pediatric oncology

STAT now publishes selected Letters to the Editor received in response to First Opinion essays to encourage robust, good-faith discussion about difficult issues. Submit a Letter to the Editor here, or find the submission form at the end of any First Opinion essay.

“Diagnostic tests for rare conditions present a mathematical conundrum,” by Manil Suri and Daniel Morgan

I am a first-year medical student, and up until a few weeks ago, I would have made the same error Dr. Suri and Dr. Morgan highlighted and misinterpreted “a 1% false positive rate to mean that a positive result has a 99% chance of being correct.” Luckily, in my epidemiology and biostatistics course, we learned how even an exquisitely sensitive and specific test can have a low positive predictive value if the prevalence of a disease is low and therefore there are simply few true positives out there. It is a counterintuitive notion that a “good” test might not tell you very much definitively if it’s positive, but I have come to realize a lot of statistical concepts can be counterintuitive. My experience shows how important it is for medical students to be learn the basic principles underlying diagnostic and screening tests. As the authors note, more and more of these tests are becoming available every day both to physicians and the public. The costs both monetarily and of misinterpretation or misuse to patients is growing, too. Dr. Suri and Dr. Morgan have touched on a vital issue that cuts across regulation, medical education, and clinical practice.
— Caleb Rhodes, Perelman School of Medicine at the University of Pennsylvania

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How very sad, even tragic, that this information about the predictive value of tests for rare diseases is so little known even among physicians. I was taught it in medical school in 1968! And so many diseases and conditions are uncommon enough to be wary of a positive result of a screening test.
— James Gibson, South Carolina Dept of Health and Environment, ex-CDC

“Big Weed today is a whole lot like Big Tobacco in the 1950s,” by Thomas Farley

This article is almost out of date and shows the author doesn’t understand current regulations, doesn’t understand differences between tobacco, alcohol, and marijuana and is sensational.
— Peter Jackson

“A well-meaning FDA policy is a threat to pediatric cancer treatment,” by E. Anders Kolb

I appreciate this perspective from Dr. Anders and the identification of potential unintended consequences in the pediatric space. But I wish this article had included the potential financial conflicts of interest here. Dr. Anders’ organization, the Leukemia & Lymphoma Society, list more than 10 drug companies among their corporate sponsors (see annual report). Dr. Anders himself received about $40,000 from 2018-2022 in consulting fees from drug companies Novartis, Jannsen, and Sanofi, according to CMS Open Payments. This information provides important context for his view of “Let’s get these drugs to children as quickly as possible to see if they work and optimize the doses later.”
— Judith Garber, Lown Institute