Four Things No One Tells You About Biomedicine
Confused about the latest news in medicine? You should be.
Posted May 31, 2018
Eating fruits and vegetables can help prevent colon cancer. Getting regular mammograms helps detect breast cancer. Taking Nexium can help your reflux.
Well, not really. Or, more accurately—yes, but no. The public feels whipsawed by dietary advice that changes every decade, as well as by healthcare recommendations that make the news cycles but leave us more puzzled than informed. But, if you understand how biomedicine works, and the way we report discoveries in biomedicine, these wild shifts in the opinions of experts that seem to dart about as unpredictably as schools of minnows suddenly seem explicable.
First, biomedicine is remarkably complex, and our net knowledge of its workings is akin to taking a pocket flashlight into Yankee Stadium at midnight during a blackout and trying to identify things that lie outside your modest cone of light. Would that diet and exercise were the only variables involved in maintaining a healthy weight, instead of the roles also played by inflammation, the makeup of your microbiome, and changes to mitochondria caused by even modest gains in weight.
Second, controlled, longitudinal studies of diet and exercise are all but impossible. For starters, a study with the kind of rigor reserved for randomized, controlled trials of drugs would require participants to remain in an environment that completely restricts participants’ diets and dictates exercise over the course of years, not weeks—an impossibility as few patients could afford to stay completely within a clinical environment and no Institutional Review Board would even approve the protocol due to its potentially deleterious effects on participants’ lives. (A tightly controlled study would supervise even participants’ visits with family members who might smuggle in forbidden foods.) Studies thus rely on participants’ own food diaries, notoriously unreliable, as most of us underestimate the amount we eat while overestimating the exercise we get. A food diary of a participant on, say, the notoriously spartan Pritikin-style diet, limiting fats, sugars, carbohydrates, and sodium, is hardly going to cop to scarfing down a Big Mac in a moment of weakness during Month 19.
Third, the medications you’re taking have what we might think of as an X-factor to them, otherwise known to clinicians as Number Needed to Treat (NNT). An ideal NNT would be 1. However, for some treatments like using Nexium or one of the other commonly-prescribed proton pump inhibitors (PPIs) to treat gastroesophageal reflux disease (GERD), the NNT is 25. Tellingly, a meta-analysis of eight studies of PPI therapies for the treatment of GERD found no statistical benefit from using them over a placebo—which might make you think twice about paying a buck a pill for the over-the-counter versions.
And that screening for cancer that’s supposed to save lives? Some of it does more harm than good, including the highly sensitive digital mammograms that initially led to a spike in the number of surgeries to remove what turned out to be harmless fatty blips in patients’ breast tissue. Moreover, the standard prostate cancer screening men schedule with their doctors after age 45 has its own X-factor, the Number Needed to Screen (NNS), which is 1410, a far cry from the ideal of 1. Put simply, nearly one and a half thousand men need to get screened for prostate cancer to prevent a single death. In the meantime, men told they have prostate cancer—usually indolent, the equivalent of those fatty blips in breast tissue that will only turn up on autopsy, after something else kills you—receive a staggering $1.5 billion in needless prostate biopsies (never a picnic, as procedures go) and $58.7 million in unnecessary surgeries or radiation that can lead to urinary incontinence and erectile dysfunction. Put simply, we believe most tests are more reliable than they are, and American doctors err on the side of giving patients too much treatment to avoid lawsuits rather than advising a wait-and-see approach.
So what can the public do, faced with these four glaring shortcomings of the health advice we receive at the doctor’s office or hear about in the news? Treat announcements with skepticism. If you can, read a bit more about related studies. And ask questions at your doctor’s office. The digital world we now live in makes becoming better informed easier than ever before. We just need to make the effort.
Andriole GL, Crawford ED, Grubb RL, et al. (2012) Prostate cancer screening in the randomized Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial: mortality results after 13 years of follow-up. Journal of the National Cancer Institute 104: 125-132.
Crawford, E., Black, L., and Eaddy, M. et al. (2010). A retrospective analysis illustrating the substantial clinical and economic burden of prostate cancer. Prostate Cancer and Prostatic Diseases 13: 162-167.
Etzioni R, Penson DF, Legler JM, et al. (2002) Overdiagnosis due to prostate-specific antigen screening: lessons from US prostate cancer incidence trends. Journal of the National Cancer Institute 94: 981-990.
Gralnek, I. M. Dulai, G. S. Fennerty, M. B. et al. (2006) Esomeprazole versus other proton pump inhibitors in erosive esophagitis: a meta-analysis of randomized clinical trials. Clinical Gastroenterology and Hepatology 4: 1452-1458.
Loeb S, Vellekoop A, Ahmed HU, et al. (2013). Systematic review of complications of prostate biopsy. European Urology 64: 876-892.
Loeb S, Vonesh EF, Metter EJ, et al. (2011) What is the true Number Needed to Screen and treat to save a life with Prostate-Specific Antigen testing? Journal of Clinical Oncology 29: 464-467.
Qadeer MA, Phillips CO, Lopez AR, et al. (2006) Proton pump inhibitor therapy for suspected GERD-related chronic laryngitis: A meta-analysis of randomized controlled trials. The American Journal of Gastroenterology 101: 2646.