June 6th, 2012
Selections from Richard Lehman’s Literature Review: June 6th
CardioExchange is pleased to reprint selections from Dr. Richard Lehman’s weekly journal review blog at BMJ.com. Selected summaries are relevant to our audience, but we encourage members to engage with the entire blog.
Lancet 2 Jun 2012 Vol 379
Meta-analysis of cIMT and Clinical Outcome (pg. 2053): The massacre of the surrogates continues, and it is tempting to stand by and gloat, like King Herod or Genghis Khan. But there was a time when I really wanted to believe in these things, as the short cuts that medicine needed to move faster. This wishful thinking was widespread, and much encouraged by the pharmaceutical industry – which is busy inventing new surrogates to this day, hoping to avoid the lengthy trials needed to achieve true knowledge based on hard outcomes. How nice it would be if all that we needed to predict cardiovascular outcomes was the progression of carotid intima-media thickness. But contrary to popular belief, this measurement has no useful predictive value. The conclusion of this meta-analysis of individual patient data is unusually clear: “The association between cIMT progression assessed from two ultrasound scans and cardiovascular risk in the general population remains unproven. No conclusion can be derived for the use of cIMT progression as a surrogate in clinical trials.” So how come the entire medical community fell under this delusion?
BMJ 2 Jun 2012 Vol 344
Scoring the Risk Scores: John Ioannidis leads his Stanford team in an exploration of 20 different articles on cardiovascular risk scores. So which scores as the Score of Scores in this score of scores? Impossible to say, he concludes, as they are all derived in different ways and have only one characteristic in common: “authors always reported better area under the receiver operating characteristic curves for models that they themselves developed.” If someone as sharp as John can’t pick a favourite, what hope for the rest of us? I guess my own for UK use is QRISK2, but don’t all pelt me with tomatoes. I will do whatever you say.
Door- vs. Onset-to-Balloon Times: An observational study from 26 tertiary hospitals in Japan confirms common sense and previous evidence: the thing that matters in ST elevation myocardial infarction is not door-to-balloon time but onset-to-balloon time – and that beyond 2 hours, there is little difference in outcomes of death and heart failure at 3 years.
Sundry Reviews: As there is so little original research in the journals this week, forgive me for puffing two superb pieces by friends in this week’s print BMJ: Preventing overdiagnosis: How to stop harming the healthy by Ray Moynihan, Jenny Doust, and David Henry; and The drug industry is a barrier to diabetes care in poor countries by John Yudkin. Putting these pieces behind a paywall is also a barrier to care in poor countries.
CVD Death by Chocolate: Finally, in response to a specific plea, I am travelling to the BMJ website to comment on the already famous paper about chocolate consumption in people with high cardiovascular risk. Ever since delicious solid chocolate was invented in Britain in the late 1840s, people have used it for modelling. This has given rise to the highly inventive Yorkshire term of derision, “Ee, th’art as much use as a chocolate fireguard.” This paper takes the process a step forward. It uses a Markov model to predict the effects of dark chocolate on cardiovascular outcomes over 10 years in high-risk individuals, based on the known effects of chocolate on blood pressure and lipids over a period of 2 to18 months. Now at least you can eat a chocolate fireguard, as my wife was quick to point out. But it’s impossible to swallow this Markov model, however hard you try. Henceforth we will be able to call all modelling studies that make wild extrapolations “as much use as a chocolate Markov model.” And although this is written up as a serious study, I wonder if the Australians who wrote it didn’t have their tongues firmly in their cheeks. Maybe they are now all laughing into their Fosters at pulling one over so many credulous Poms and Yanks.