June 10th, 2013
Selections from Richard Lehman’s Literature Review: June 10th
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.
JAMA 5 June 2013 Vol 309
Roux-en-Y Gastric Bypass vs. Intensive Medical Management for the Control of Type 2 Diabetes, Hypertension, and Hyperlipidemia (pg. 2240): Last week, Edwin Gale’s brilliant Lancet essay reminded us that type 2 diabetes is a category error. It can be treated with glucose-lowering agents and “cured” by bariatric surgery, but in the end only one thing matters: do these treatments improve life for patients? Measurements like fasting blood sugar, HbA1c, body mass index, and blood pressure are after all just surrogates. Age also comes into the equation: if, in retirement, my enjoyment of food causes me to get fatter and develop “type 2 diabetes,” I really won’t care very much. But if I were a Bangladeshi woman aged 40 with a BMI of 38 and diabetic neuropathy, expected to stay at home and look after five children and a couple of elderly relatives, I might take a quite different view. It is long term quality of life which counts. Quantity of life is also a factor. And for bariatric surgery, as for every other diabetes treatment, we know too little about these to make a clear judgement. The results of this trial are nonetheless very useful, because the comparator was the most intensive lifestyle modification possible, and the population from the US and Taiwan had a mean age of 49 and BMIs ranging from 30 to 40. The patients randomized to Roux-en-Y gastric bypass lost 26% of their body weight and ended up requiring much less medication for glucose, blood pressure, or lipids. But there were some unpleasant surgical complications, including one case of brain and limb damage. This was a smallish trial (n=120) with a huge number of exclusions: further individual patient follow-up data, hopefully available to all, will go into the great evidence pool which will eventually give us some clear answers about how to treat diabetes.
Bariatric Surgery for Weight Loss and Glycemic Control in Nonmorbidly Obese Adults With Diabetes (pg. 2250): Here is the same thing, expressed in the words of systematic reviewers who went through as many articles as they could in this fast-developing field (32 surgical studies, 11 systematic reviews on nonsurgical treatments, and 11 large nonsurgical studies published after those reviews). “Current evidence suggests that, when compared with nonsurgical treatments, bariatric surgical procedures in patients with a BMI of 30 to 35 and diabetes are associated with greater short-term weight loss and better intermediate glucose outcomes. Evidence is insufficient to reach conclusions about the appropriate use of bariatric surgery in this population until more data are available about long-term outcomes and complications of surgery.” In fact only three medium sized randomised trials really met the original criteria for this systematic review, and individual patient data were only available for one of them. The science of medicine really cannot advance while so much data that should inform decision making remains beyond reach.
Treating Diabetes With Surgery (pg. 2274): And there is a very good editorial on the subject as well. It ponders this very question—how can you do a systematic review that is both rigorous and clinically useful? “Too limited inclusion criteria result in no guidance for clinicians caring for certain patients and criteria that are too broad lead to recommendations that represent expert opinion. Expert opinion cannot be viewed as evidence or serve as the basis for practice guidelines.” Amen. Is anyone at NICE listening?
BMJ 8 June 2013 Vol 346
Risk of Incident Diabetes Among Patients Treated with Statins: Statins lower plasma HDL-cholesterol markedly in everybody and raise plasma glucose a little in some. These measurements mean nothing in themselves: the only important fact is that statins lower cardiovascular risk in everybody, irrespective of its absolute starting point. The choice of whether to use a statin should be left to the patient on the basis of a calculation of individual risk reduction. “Diabetes” is just a glucose threshold: we have no idea what “diabetes” implies when it used to designate a person who has moved from having a fasting glucose of 6.7 to 7.2 because they are taking a statin. The population study from Canada in this week’s BMJ simply grades the various statins according to their likelihood of raising blood glucose, and shows that this corresponds to their degree of HMG-CoA reductase inhibition. That’s still quite an achievement, and this paper continues the marked improvement in quality of the research section in the BMJ.
Ann Intern Med 4 Jun 2013 Vol 158
Aspirin vs. Low-Molecular-Weight Heparin for Extended VTE Prophylaxis After Total Hip Arthroplasty: Aspirin of course began life as an analgesic, but today if you stopped any doctor in the corridor and asked what the action of aspirin is, you would be told “platelet inhibitor” 19 times out of 20. Aspirin’s mode of action makes it a much weaker anticoagulant for preventing thromboembolism than low molecular weight heparin, but there seems to be one situation where the two are equivalent: in extended prophylaxis for patients who have had total hip replacement. A large Canadian trial randomized patients to receive either dalteparin or aspirin for thromboprophylaxis after ten days on dalteparin following hip arthroplasty. There was no significant difference in either venous thromboembolism or major bleeding.