Tag Archives: medical science

Image result for stethoscope Dr. John Mandrola (physician and medical writer) has once again written thought provoking posts about medicine and the need for people to question tests, procedures, screening, and to look at the harms and benefits. Because YES - all of the above have harms and benefits, even something as "minor" as taking an antibiotic for a week or two (for example, effects on the gut microbes).

Excerpts from his April 20 post at drjohnm.orgTrust and Medical Science

I first addressed the lack of skepticism among my colleagues. I argue that doctors have become a rapturous audience for medical news. We too easily accept flawed evidence. Our embrace of a flawed dissolving coronary stent and a left atrial appendage closure device serve as good examples of misplaced optimism.

In the second section of the essay, I explore the problem with overselling science. Here’s an except: Science does not do itself. Humans—bent on having a successful academic career—do science. This means positive results can become the goal rather than the pursuit of scientific truth.

I spent three paragraphs on evangelism over screening healthy people. It crushes the public trust to say “screening saves lives” when the evidence doesn’t support the claim. This is not a typo. I cite numerous studies that show common screening tests, mammography, PSA tests, colonoscopy, when put to the test of a randomized controlled trial, do not lower overall death rates.

The obfuscation comes when screening advocates tout lower disease-specific death rates. Viz, mammography may (slightly) lower the chance of dying from breast cancer but it has no significant effect on all-cause death. Through a colleague [Dr. B. Mazer] on Twitter, I found a wonderful quote on the folly of trying to reduce your risk of dying from one sort of disease. “If you are a patient contemplating some screening test, and the result of that test or treatment is no measurable reduction in the rate of death at some clinically relevant later point in time, then why have the test or treatment—unless the patient, for some reason, has a desire to die from condition A instead of condition B.”

And excerpts from his commentary on this topic at Medscape: Want More Trust in Medical Science? Embrace Uncertainty and Cut the Hype

I see a lot of overconfidence in medical science. At the bedside, clinicians—myself included—underestimate harms and overestimate benefits of medical intervention. These inaccuracies have many causes. One is a lack of skepticism. It was 10 years into practice before I learned that most of a study's bias comes in its planning, in the questions it asks.

Rarely do I hear a practicing colleague or speaker at a medical meeting cite Dr John Ioannidis's famous 2005 paper "Why most published research findings are false." Ioannidis, a Stanford epidemiologist, argues that small sample sizes, tiny treatment effects, "flexible" study designs (which can transform "negative" into "positive" results), prestudy biases, and conflicts of interest are the root causes of false research findings. Research findings, he argues, may simply be an accurate measure of the prevailing bias.....Richard Horton, the editor of the Lancet, agrees with Ioannidis. In 2015, he wrote that "much of the scientific literature, perhaps half, may simply be untrue." One of the (many) reasons for this crisis, Horton adds, is that "in their quest for telling a compelling story, scientists too often sculpt data to fit their preferred theory of the world." 

Another group of academics that threaten the public trust are screening evangelists. Screening is precarious because it puts doctors close to breaking the golden rule—first, do no harm. Doing things to people-without-complaints and promoting the slogan "screening saves lives" should require clearing the highest bar of evidence. The truth, though, is that the evidence does not support such zealous advocacy.

A systematic review of meta-analyses and randomized clinical trials that studied screening of asymptomatic adults for 19 diseases (39 tests, including mammography) found reductions in disease-specific mortality were uncommon and reductions in all-cause mortality were very rare or nonexistent. Prasad and colleagues explain how screening advocates conflate disease-specific death rates with overall mortality. "Using disease-specific mortality as a proxy for overall mortality," they wrote in the BMJ, "deprives people of information about their chief concern: reducing the risk of dying."

Another good Dr. John Mandrola post: Four Crucial Questions To Ask Your Doctor