Evidence trumps opinion - again

If you're not regularly reading the blog Junk Food Science, you're missing some good stuff.  Today's post is another gem:  "Seeing the evidence: tighter control of blood sugars in type 2 diabetics." It's an important insight into a critical flaw in how we process medical evidence.  As poet-philosopher George Santayana famously observed:  "Those who cannot learn from history are doomed to repeat it."  There's an important lesson here.

In this case, blogger Sandy Szwarc reviews a recent meta-analysis of the health outcomes of high quality trials of interventions more tightly controlling blood sugars.  Forget for a moment the literature showing that low-salt diets increase insulin resistance, the point is the process of substituting well-publicized, lower quality studies as summarized by expert "consensus" for reliance on the available quality data.  That is a pattern we've seen in the salt and health controversy as well.  The blog's well worth reading, but, bottom line, Szwarc summarizes:

To this day, no sound clinical study has ever shown that treating type 2 diabetics to achieve even lower blood glucose levels provides added benefits that outweigh the harms. Treating a number that is a symptom of a disease doesn't mean the disease process has been changed. Lowering health indices in elderly patients to match those of healthy 20 year olds doesn't mean their risks will be lowered to those of 20-year olds again. And minimizing the risks associated with extremely high lab values doesn't mean that "how low can you go" is better for patients.

Busy medical practitioners rely heavily on experts' assessments of research findings, but those assessments are fraught with biases. As Dr. John P. Ioannidis, M.D., at the University of Ioannina School of Medicine in Ioannina, Greece, and with the Institute for Clinical Research and Health Policy Studies at Tufts-New England Medical Center, Tufts University School of Medicine in Boston, cautioned: "Empirical evidence on expert opinion shows that it is extremely unreliable." As we also see time and again, the analyses and conclusions made by study authors and industry experts often differ from what the data actually shows. Bias doesn't always come from financial conflicts, but can come simply from a belief in a popular scientific theory. It can lead even medical professionals to see only what supports a theory: confirmation bias.

Myths can take on lives of their own even in medicine unless we look objectively and carefully at the evidence. Only with unbiased discussions can we ever hope to turn evidence-based medicine into evidence-based medicine.

Pray for poetic philosophy -- and hard data.