Beware of Expert Panels

 

Ioannidis has written an interesting article (1) about biomarker failures, but I don’t agree with his first example of a failure. He says that PSA is a failure and “largely useless— or even harmful—and therefore needs to be abandoned.” He offers as evidence the recent USPSTF recommendation, which recommends against PSA screening altogether (2). 

But there are several reasons to question abandoning PSA. For one, the USPSTF data analysis has been challenged (3). Secondly, an update (4) from the ERSPC Trial showed that PSA screening does significantly reduce death from prostate cancer whereby a man who undergoes PSA testing will have his risk of dying from prostate cancer reduced by 29%. And thirdly, one can question whether cost played a role in the USPSTF conclusion. The USPSTF is empowered by the Affordable Care Act. Ezekiel Emmanuel, President Obama’s special health care advisor suggested  (5) that “the complete lives system produces a priority curve on which individuals aged between roughly 15 and 40 years get the most substantial chance [of healthcare resources], whereas the youngest and oldest people get chances that are attenuated.” PSA screening has been recommended to start at age 50.

There would be considerable cost savings for: 

  • the population of men over 50 in the US (or between 50 and 75) that would no longer receive a PSA test
  • the number of men that would have had an elevated PSA that would not receive a biopsy
  • the number men that would have been diagnosed with early prostate cancer via a PSA test / biopsy (~ 200,000 per year) that would not receive treatment (surgery or radiation) 

So in spite of the fact that PSA has many false positives (and some false negatives) and that there is overtreatment of prostate cancer, just because an expert panel concluded to abandon PSA, this does not mean it is the right conclusion. 

References 

  1. Ioannidis JP, Biomarker Failures Clin Chem 59 in press.
  2. Moyer VA, on behalf of the U.S. Preventive Services Task Force. Screening for prostate cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2012;157:120–34.
  3. Schröder, FH, Stratifying Risk — The U.S. Preventive Services Task Force and Prostate-Cancer Screening N Engl J Med 2011; 365:1953-1955.
  4. Schröder, FH, Hugosson, J, Roobol, MJ, et. al. Prostate-Cancer Mortality at 11 Years of Follow-up N Engl J Med 2012;366:981-90.
  5. Persad G, Wertheimer A, Emanuel EJ, Principles for allocation of scarce medical interventions. Lancet 2009; 373: 423–31.
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