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Archive for July, 2011

EBM (the practice and the journal) takes a ribbing

11 Jul, 11 | by EBM

A writer at the Boston Globe is annoyed by the terms “evidence-based medicine” (and “reality-based community” and “fact-based presidency,” among others that he calls verbal tics).  Surely these terms have become overused. But they have become overused because people want to base decisions in evidence.  But the reporter scoffs at the BMJ (and the journal EBM) by quoting the long-accepted (since around 1992) definition of EBM and mocking it.

About “evidence-based medicine” he asks, “As opposed to what?”, making the same mistake many learners make when they first hear about EBM. He believes the practice of medicine must all be evidence-based and is unaware that anything else could go on, or that it might be complicated to identify and apply evidence. Clearly EBM (the practice and the journal) is about using the best evidence.

Anyway, the reporter’s piece and my response can be seen here…as per my tweet earlier today “EBM and BMJ taunted by Boston Globe writer last week. EBM responds…See it in the Globe today ” and follow me @EvidBaseMed_BMJ

Universal screening with computed tomography for lung cancer? Finally a randomized trial…but what to do??

11 Jul, 11 | by EBM

Expert opinion and observational studies have favored lung cancer screening but trials (of plain xrays) have not shown benefit, until now. For years, many have been asking for a randomized trial. Now that the results of the (US) National Lung Screening Trial (NSLT) have been published, it reminds me of the admonition to “be careful what you ask for, you just might get it.”

The randomized trial compared three screenings, either low dose CT scans or plain chest radiographs and adherence to the screening protocol was >90%.  How to address a positive test was left to clinicians outside the trial. It enrolled 53 454 participants age 55-74, who smoked at least 30 pack-years currently or who had quit in the past 15 years, and had not had lung cancer or a recent chest CT scan, hemoptysis or unexplained weight loss. The authors estimate only 7% of US current or former smokers would meet these criteria. So the study results do NOT apply to 93% of smokers. One wonders though, to whom they will be applied (paying customers?).

What were the results? Amazingly, despite the publication source (New England Journal of Medicine, and widely agreed upon reporting guidelines, the main results are presented as relative reductions, making them seem large (a 20% decrease in death from lung cancer). I don’t mean to minimize though, just to be clear—it is important that there was a reduction, and more lung cancers were diagnosed in the (low dose) CT group, which had fewer lung cancer deaths. The absolute reduction was the difference between 356 lung cancer deaths in 144,103 person-years in the CT group and 443/143,368 in the plain x-ray group. The absolute risk of lung cancer death among those screened at least once was 1.3% in the CT group, 1.6% in the x-ray group, an absolute risk reduction of 0.312%, for a number needed to screen with 3 tests of 320 to prevent 1 lung cancer death over 7 years. Overall mortality was also reduced (by 0.5%). Complications of evaluation of a positive test were 1.4% in the CT group, 1.6% in the x-ray group.
The vast majority of positive tests were false positives (96% in the CT group, 95% in the x-ray group).

None of this addresses long term cumulative population harms from radiation exposure or any impact on likelihood of quitting smoking.

What to do? Many may reach different conclusions depending on the presentation of the results. Others will take these results and then add patient values and preferences. Others still may wish to wait to see the cost effectiveness analyses.

What will you do? You now have the evidence…

Actually Accessible Evidence for Patients re: Prescription Drugs?

5 Jul, 11 | by EBM

Pharmaceutical company advertisements (at least in the US) dutifully list a litany of side effects and other risks after presenting their benefits. Package inserts and many drug reference materials for health professionals do the same. The written lists are exhaustive and the print small, and in audiovisual ads the lists are read aloud faster than a seasoned auctioneer can run through bids. The drug makers are doing what is required of them by regulatory agencies. But the information is not usable by patients or even clinicians. Wouldn’t it be nice if patients and doctors could find the information they want and need easily? For example, how well does the drug work? What are the main side effects and risks and how often do they occur?

Woloshin & Schwartz propose a simple solution. Information boxes on medications similar to those on bags of potato chips or cereal boxes. But these boxes would clearly state outcomes of randomized trials quantifying results in medication versus placebo groups (e.g. absolute risks). Patients (and doctors) would then have information they can use when making decisions. A simple idea, with evidence in the literature already to support it. Their advice to the US Food and Drug Administration appears in today’s New York Times Here at Evidence-Based Medicine, I would welcome papers on other innovations in communicating evidence to patients, and clinicians.

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