January 12th, 2012

Selections from Richard Lehman’s Weekly Review: Week of January 9th

Richard Lehman, MDCardioExchange is pleased to be able to reprint selections from Dr. Richard Lehman’s journal review: a weekly blog at BMJ.org offering commentary on the latest literature.  Dr. Lehman is a British general practitioner who started these reviews 14 years ago as brief notes to encourage further reading discussion among friends and colleagues. In his own words, they are still written in a style that tries to provoke and engage the reader while conveying the message of the articles from the point of view of a generalist trying to work out what matters for patients.

Each week, we’ll pull out a couple of his summaries that are relevant to this audience, but we encourage members to engage with the entire blog.

Week of January 9th

(click here to read the full review at the BMJ)

JAMA  4 Jan 2012  Vol 307

56    If you look at obesity measured by BMI, and then adjust for insulin resistance, hyperlipidaemia and high blood pressure, weight as such is actually a weak predictor of cardiovascular risk. Which may explain why the absolute benefit of bariatric surgery is not enormous, and is probably non-existent for obese individuals without other risk factors. This is a report from the Swedish Obese Subjects (SOS) study at a median of 14.7 years, and it shows a halving of cardiovascular events in the group treated with bariatric surgery. That sounds impressive, but absolute mortality difference actually amounts to 1.3% in favour of surgery. And the benefit was not related to baseline BMI in this study. Even longer term data are needed.

66     I have spent several afternoons over the last few months listening to presentations on readmission rates in US hospitals, wondering all the while how these compare with other health systems. For myocardial infarction, they are very high compared with other developed countries. “However,” say the authors, “this difference was greatly attenuated after adjustment for length of stay.” In other words, the facts that the US has the shortest stays for MI, and the highest readmission rates, are not unconnected.

NEJM  5 Jan 2012  Vol 366

9     A new era in secondary prevention after acute coronary syndrome is the headline of one birthday editorial, celebrating the success of low-dose rivaroxaban in reducing a composite end-point of death from cardiovascular causes, myocardial infarction, or stroke in 15,526 patients with recent ACS. And to be fair, this amounted to an actual (small) tally of lives saved: total mortality was reduced from 4.5% to 2.9%. It would take any competitor a comparable amount of effort to show benefit from its own fixed-dose anticoagulant, and two have already tried and failed (apixaban and dabigatran), perhaps because the dosing was wrong. Rivaroxaban also failed at a dose of 5mg b.d., but by halving this it was changed from an agent that caused too many bleeds to one which prevented more events than it caused. Good news for Johnson & Johnson and Bayer shareholders, then: but for post-ACS patients and health systems struggling to contain costs? For these, the “new era” is a mixed blessing: someone will need to interrogate the individual patient data from this vast 766-centre trial, and then we will have to wait at least a decade for evidence from trials of equal size to find out the optimal anticoagulant/antiplatelet cocktail for post-ACS patients.

20    But at least we can cross vorapaxar off the list right away: this new oral protease-activated–receptor 1 (PAR-1) antagonist that inhibits thrombin-induced platelet activation simply caused more bleeds in post-ACS patients, without any countervailing benefit. That’s a pity: I rather like the name. (I took a shine to vorapaxar: What a shame we had to axe her).

2 Responses to “Selections from Richard Lehman’s Weekly Review: Week of January 9th”

  1. Robin Motz, M.D., Ph.D. says:

    Now why didn’t some editor point out the inverse relationship between length-of-stay and number of re-admissions?

  2. Dan Hackam, MD PhD says:

    Adjusting for cholesterol, BP, insulin resistance, triglycerides etc, in the association of obesity with CV risk, is a classic example of overadjustment in explanatory epidemiology (it may be acceptable in predictive models, but not explanatory ones). These are all intermediate steps interposed between weight gain, especially visceral weight gain, and CV risk. In addition, most patients need carbohydrate restriction to lose weight. The established causal pathway is: CHO excess –> hyperinsulinemia –> weight gain –> downstream CV surrogates –> CV risk.