Friday, February 28, 2014

Overediagnosis and Mitigated Overdiagnosis: Ongoing problems with Breast and Lung Cancer Screening

I got to thinking about cancer screening (again) in the last week after reading in BMJ about the Canadian National Breast Screening Study (CNBSS).  That article piqued my interest because I immediately recalled the brouhaha that ensued after the U.S. Preventative Services Task Force (USPSTF) recommended that women not get mammograms until  age 50 rather than age 40.  That uproar was similar to the outcry by urologists when the USPSTF recommended against screening for prostate cancer with PSA testing.  Meanwhile, changes in the cholesterol guidelines have incited intellectual swashbuckling among experts in that field.  Without getting into the details, observers of these events might generate the following hypotheses:
  1. People are comfortable with the status quo and uncomfortable with change
  2. People get emotionally connected to good causes and this makes the truth blurry, or invisible.  After you've participated in the Race for the Cure, it's hard to swallow the possibility that the linchpin of the Race might not be as useful as we thought; and is no longer recommended for a whole swath of women. 
  3. People are terrified of cancer
  4. Screening costs money.  Somebody pockets that money.  Urologists and radiologists and gastroenterologists LOVE screening programs.  So do Porche dealers.

Monday, February 10, 2014

Brief Updates on Hypothermia, Hyperglycemia, Cholesterol, Blood Pressure Lowering in Stroke and Testosterone

I've read a lot of interesting articles recently, but none that are sufficient fodder for a dedicated post.  So here I will update some themes from previous blog posts with recent articles from NEJM and JAMA that relate to them.

Prehospital Induction of Hypothermia After Cardiac Arrest
In this article in the January 1st issue of JAMA, investigators from King County Washington report the results of a trial which tested the hypothesis that earlier (prehospital) induction of hypothermia, by infusing cold saline, would augment the assumed benefit of hypothermia that is usually initiated in the hospital for patients with ventricular fibrillation.  Please guess what was the effect of this intervention on survival to hospital discharge and neurological outcomes.

You were right.  There was not even a signal, not a trend towards benefit, even though body temperature was lower by 1 degree Celcius and time to target hypothermia temperature in the hospital was one hour shorter.  However, the intervention group experienced re-arrest in the field significantly more often than the control group and had more pulmonary edema and diuretic use.  Readers interested in exploring this topic further are referred to this post on Homeopathic Hypothermia.

Hyperglycemic Control in Pediatric Intensive Care
In this article in the January 9th issue of NEJM, we are visited yet again by the zombie topic that refuses to die.  We keep looking for subgroups or populations that will benefit, and if we find one that appears to, it will be a Type I error, thinks the blogger with Bayesian inclinations.  In this trial, 1369 pediatric patients at 13 centers in England were randomized to tight versus conventional glycemic control.  Consistent with other trials in other populations, there was no benefit in the primary outcome, but tightly "controlled" children had much more and severe hypoglycemia.  The "cost effectiveness" analysis they report is irrelevant.  You can't have "cost effectiveness" of an ineffective therapy.  My, my, how we continue to grope.