MDs seduced by technology

Coronary angiography used in ON before benefits proven, says study

By Giancarlo La Giorgia

Cardiologists in Ontario increased their use of coronary angiography following acute myocardial infarction (AMI) dramatically in late 1998 — 11 months before the first positive trial results appeared in the literature. That's the rather surprising finding of a new Canadian study published in the April 23 issue of the Archives of Internal Medicine. Interestingly, the use of cholesterol-lowering statins post-AMI, which peaked around the same time, occurred almost four years after the benefits of such treatment had been published.

"We looked at statins as a control comparison. Unlike with coronary angiography, the inflection point of their usage followed the establishment of clear scientific evidence showing their effectiveness," says Dr David Alter, the study's lead investigator and a cardiologist at Sunnybrook and Women's College Health Sciences Centre.

TECH ON TRIAL
Dr Alter and his colleagues considered the FRISC II trial, published in The Lancet in 1999, to be the first randomized controlled trial showing the benefit of post-AMI angiography. With regards to statins, they looked at the Scandinavian Simvastatin Survival Study (4S) that appeared in the same journal in 1994 as the first report favouring the use of statins for secondary prevention of coronary artery disease.

The spike in statin prescriptions came after a considerable delay, whereas coronary angiography was provided to both high- and low-risk AMI populations before FRISC II's publication — regardless of whether the admitting hospitals had on-site capacity to perform the procedure.

Dr Alter's study looked at AMI patients over 65 admitted to hospital in Ontario between 1992 and 2004, examining the use of in-hospital angiographies, as well as statin use within 30 days of post-hospital discharge. According to Dr Alter and his colleagues, the initial growth in capacity and subsequent use of angiography was likely driven by 'perceived' population needs, as well as the lure of a new technology.

"I find it alarming that physicians' perceptions of how well something works, rather than the best science, is driving medical practice," says Dr Alter, adding that while evidence of the benefits of coronary angiography post-AMI did eventually emerge, this was "a bit of good luck and clairvoyance." "There are several technologies that were thought to be good and utilized en masse. But ultimately, there's been a surprising lack of evidence supporting them and even a potential they may cause harm." He mentions drug-eluting stents as an example. The stents were initially considered good for the majority of people undergoing angioplasty, but recent studies have thrown this practice into question.

SONG OF EXPERIENCE
Dr Lyall A Higginson, president of the Canadian Cardiovascular Society and a cardiologist in Ottawa, could not disagree more. "There is often a gap of a year or longer between the time scientific evidence is known within the medical community and when it is published," he argued, adding that, "we knew several months before FRISC II that there were benefits to angiography and possible revascularization for people who had AMIs. In fact, the Thrombolysis in Myocardial Infarction IIIb trial, published in 1995, showed that there were shorter hospitalizations, fewer re-admissions, fewer recurrent symptoms and half the need for invasive assessment if cardiac catheterization was done early." In Dr Higginson's opinion, all FRISC II did was prove what Ontario cardiologists knew all along.

But both physicians agree invasive procedures like this shouldn't normally be used pre-emptively. "The problem is, when we have it wrong about a technology, it can be devastating to patients and subjects them to unnecessary tests and interventions, some of which can be harmful," says Dr Alter. "Also, enormous amounts of money are spent on these technologies, some of which might have been better spent elsewhere."

He admits that diagnostic and interventional technologies have an important place in medicine, but believes that most lack either rigourous scientific evidence showing their benefit or study into whether increasing investment has led to better patient outcomes. "Pouring money into angiography, MRI or other diagnostic procedures to shorten waiting lists is great for optics, but it isn't clear that the demand itself is justified," argues Dr Alter.

Dr Alter says that policymakers should raise the bar of approval for medical technologies and demand more clinical trials. Likewise, evaluative field studies should be conducted after approval to ensure that resources are being allocated appropriately and used effectively.