delanceyplace.com 11/2/12 - contradictory medical tests
In today's selection - the bedrock of measuring medical advances is controlled scientific tests, especially the randomized controlled tests (RCTs) that have become prevalent within the medical industry. However, all too often, the complexity and difficulty of this type of testing yields varied and contradictory results:
"Flip-flops: All of us are familiar with and frustrated by the radical shifts in opinion that come from clashing RCTs and dueling meta-analyses. ... The ... flip-flops are not course corrections. They are neck-snapping 180-degree hairpin turns that morph today's truths into tomorrow's taboos and yesterday's wisdom into today's witchcraft. Is it any wonder that compliance suffers and recommendations go unheeded? Who can really blame parents who refuse to vaccinate their children, however much we disagree? Doctors lose the credibility and trust that is our sole currency.
"Echinacea for colds? Thumbs down in 2002 and again in 2005. But a big thumbs up in 2007. The year 2010, however, brought another study and more confusion. The effects of echinacea did not reach significance but 'the trends were in the direction of benefit. . . data are also insufficient to exclude the possibility of a clinically significant effect.' The direction of benefit? Insufficient to exclude the possibility? This isn't science. It certainly isn't medicine. My homeowner's policy has clearer language than this. I hope that answers the question for you. It doesn't for me.
"Okay, thanks! Two things can be learned from this. There is no scientific design that will ever answer this question. And second, the press reported this study as definitive. The evening national network news hailed it as the last word. Think so?
"Seven hundred thousand coronary artery bypass grafts (CABG) are performed each year. In 2008 the use of an ACE inhibitor (an anti-hypertensive agent) preoperatively was strongly recommended to improve CABG survival rates. In 2009, not only was it a bad idea, it increased deaths after CABG surgery.
"That aspirin you took to prevent heart attacks? You took them for years. Many of you still do. Well, they're not on the menu any longer. We've been advised to abandon their use -- they're too dangerous. Similarly, all of us urged our patients to take folic acid for primary prevention against coronary artery disease. In 2009 it turns out that folic acid offers a 38 percent greater chance of dying from cancer.
"Do oral bisphosphonates for osteoporosis cause esophageal cancer? 'No!' say the authors of an August 2010 JAMA article. 'Yes' say the authors of a September 2010 BMJ study. What a difference a month makes.
"Mammogram anyone? If you're between forty and forty-nine years old there is not a single practitioner who will be able to make sense of the last twenty years of conflicting advice in making a recommendation. For those over eighty we thought we finally had sound advice -- no mammograms. Yet the majority of physicians order them anyway, awaiting the next RCT and avoiding the next lawsuit. In 2009, decades of evidence was turned on its head as women ran for the exits in confusion and in anger. It's still best to ask your doctor. ...
"Speaking about breasts, I bet a lot of you still perform self-examinations. You remember you were told it was important. Well, now we tell you 'Don't touch them, for God's sake. You're forcing us to do too many unnecessary biopsies!'
"Decades of evidence told diabetics to keep tight control of their blood sugars to avoid heart attacks, strokes, blindness, kidney failure, and amputations. Millions of lives were made miserable trying to balance blood sugar levels on the head of a pin. All in vain. A 2010 review of thousands of diabetics showed that this practice was not helpful for most clinical endpoints and, in fact, caused more complications than 'usual care.' Please don't get me started on PSAs (prostate-specific antigen tests). ...
" 'On Second Thought': Not only do RCTs clash with each other, sometimes there are multiple interpretations of one RCT. These 'on second thought' analyses can occur years after the facts were assumed to be in. The Women's Health Initiative (WHI), one of the largest RCTs ever performed, found that hormone replacement therapy (HRT) increased morbidity and mortality for heart attacks, strokes, Alzheimer's disease, breast and ovarian cancer, and deep vein thrombosis. The investigation was carried out by the most respected physicians, statisticians, and epidemiologists. The findings appeared in the most rigorous scientific medical journals. So compelling were the findings and the dangers of therapy, two WHI trials were halted midway out of ethical considerations (although a bit grudgingly). The use of HRT for cancer prevention and postmenopausal symptoms plummeted. Here we are seven years later and it turns out the findings were weak and not statistically significant. The conclusions were described as 'distorted,' 'oversimplified,' and just plain wrong. It was all just a 'false alarm.' "
|Steven Z. Kussin, M.D.|
|Doctor, Your Patient Will See You Now|
|Rowman & Littlefield|
|Copyright 2011 by Rowman & Littlefield Publishers. Inc.|