In keeping with my lazy habit of letting others write this blog for me, I will talk about a couple of commentaries included in the July, 2011 edition of Primary Care Medical Abstracts by my friends Rick Bukata and Jerry Hoffman. The first, I will argue, illustrates the concept previously blogged about by the anthropologist, Kalman Applbaum, on the idea of drug "channels" and how drug company marketing works to control these channels effectively. The take-home message in each case is how medical journals have been harnessed to the cause of selling drugs, despite lack of sound evidence, in ways that are usually opaque to the average reader.
Exhibit A for this commentary is a so-called expert consensus panel (McInnes et al., subscription required) on diabetic foot care, published in the British journal Diabetic Medicine. The panel appears to be what evidence-based gurus call BOGSAT, or "bunch of old guys sitting around talking," rather than a systematic evidence-based review with proper methods. The funding for the "old guys" came from a firm called SSL International, which has since been bought out by another firm, which makes a variety of health-related products, mostly for nonprescription home use. I don't see offhand that they make any diabetes drugs. Nothing is said in the article about conflicts of interest, or lack of same, among the authors.
The authors set out to answer the question of what kind of foot care should be provided for diabetics considered to be at relatively low risk. I was puzzled because the article does not say whether they are talking about Type 1 or Type 2 diabetes, so I have to imagine they mean both. It is therefore important to keep in mind that about 90 percent of patients seen by adult practitioners have Type 2 (adult onset) diabetes. As we have discussed in several previous posts, there is at present no compelling evidence that tight control of blood sugar levels (trying to get the hemoglobin A1c blood test within normal limits) effectively prevents the major complications of Type 2 diabetes, in particular diabetic neuropathy which is the cause of most foot problems.
So the "old guys" list four things that they think physicians should advise patients as part of good diabetic foot care. The second is: "maintaining adequate glycaemic control." They proceed to explain: "Numerous clinical studies have demonstrated the positive relationship between reductions in HbA1c and reduced risk of microvascular complications of diabetes, including neuropathy and foot ulcers." Now, this is sort of half right. Numerous studies have shown that if you have two groups of diabetics, one with high levels of A1c (poor control) and others with low A1c (good control), the first group will have many fewer complications. What has never been shown is that giving medicines in Type 2 diabetes to lower A1c reduces the incidence of complications.
So what evidence do these "old guys" cite to prove their point about better control leading to fewer complications, especially in the feet? They mention two references. The first, as Jerry pointed out in his commentary on the paper, was to the DCCT trial published in 1993, which showed that tight control reduced complications in Type 1 diabetics--that is, irrelevant to the vast majority of adult diabetics. The second reference is a paper by Boyko et al. in 2006. This paper has nothing to do with diabetes treatment or the prevention of complications. Rather it is the development of a prediction tool to show which diabetic patients are most likely to develop foot ulcers. Not surprisingly, one of the risk predictors is elevated HbA1c--though interestingly enough, this single factor increases one's risk of foot ulcers by only 10% above baseline, while other predictive facts double or triple the risk. But the Boyko et al. paper says nothing whatever about whether better glycemic control will prevent neuropathy or ulcers.
So what we have here in this journal is a supposed "expert consensus" on preventing foot complications in diabetics, claiming that better blood sugar control is a critical component of this prevention, but unable to cite a single clinical trial showing this to be true for the most common type of diabetes. So long as physicians think that the best way to prevent the complications of Type 2 diabetes is to lower HbA1c, they will write a lot of prescriptions for expensive medications, making the drug companies richer--but doing very little actually to prevent diabetes complications. In this way even an article that seems to be not at all about drug therapy manages to convey a drug-industry-friendly message--and the evidence be damned.
McInnes A, Jeffcote W, Vileikyte L, et al. Foot care education in patients with diabetes at low risk of complications: a consensus statement. Diabetic Medicine 28:162-167, 2011.
Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. New England Journal of Medicine 329:977-986, 1993.
Boyko EJ, Ahroni JH, Cohen V, et al. Prediction of diabetic foot ulcer occurrence using commonly available clinical information: the Seattle Diabetic Foot Study. Diabetes Care 29:1202-1207, 2006.