Friday, 28 September 2012

What kind of Evidence do we need in Surgery?

In percutaneous coronary intervention, the key to stent patency and therefore prevention of clinical events is inhibition of platelet function. Aspirin is the best know inhibitor of platelet function & has been around forever. Over the past 10 years, we have had many more - clopidogrel, abciximab, ticlopidine, pasugrel and now ticagrelor - each one shown to be superior to the last in good quality randomised controlled studies.



Yet in coronary surgery, the latest guidelines for antiplatelet therapy post CABG date back to 2004/2005 - here (page e481) and here Both of these recommend aspirin monotherapy post CABG. In the 8 years since those guidelines were published, new antiplatelet drugs have been developed, brought to market and even come off patent with cheap generics being used. I just cannot believe that these new drugs, in combination with aspirin would not be superior to plain old Bayer aspirin monotherapy after a surgical coronary artery intervention - it would not make biological sense if that was the case. Why have the trials not taken place and why have the guidelines remain unchanged?
What are the reasons for what is clearly an anachronism?
The main one is the well documented logistical difficulties and expense of carrying out large multicentre surgical trials. Trials of medicines involve comparing patients taking a blue pill to those taking a red pill - the variable wherever the patient is, in a multi centre study, is the pill.. In surgery, there are an infinite number of additional variables associated with a trial of a surgical or post surgical intervention - the surgeon, the anaethesiologist, the ICU, the hospital etc etc. Most trials of interventions that are expected to produce a modest change require large number of participants. As the number of surgical procedures carried out in any individual centre is generally smaller than the number of patients taking pills or undergoing a percutaneous procedure, than the number of centres required in a surgical trial is paradoxically larger - making the trial even more complex and expensive. These difficulties have led grant giving bodies to avoid supporting surgical trials.
Things are changing slowly. The National Institute of Health Research (NIHR), which is a research grant awarding branch of the National Health Service in the UK has in recent months given a welcome prioirty to surgical trials. In the United States, a cardiothoracic surgical trials network has been created with the help of the NIH in the US and the Canadian Institute of Health Research. The Royal College of Surgeons of England is planning to make award grants available to Speciality Research leads to promote trials in the different surgical specialities.
This increased support will in this age of austerity never be enough to overcome the huge expense and logistical headaches outlined above. The bureaucracy often associated with organising research in the UK is both off putting to potential researchers but also drains scarce resources.
We need a new approach. One thing that cardiac and other surgeons do well is record patient and operative details in surgical databases. There is a large amount of valuable data out there. We need a lowering of the bar so that evidence from strong observational studies should be sufficient for speciality or commissioning bodies to make recommendations on treatment. If this does not happen, there is a risk that surgical procedures will become even less evidence based providing those who pay for healthcare with reasons & excuses to shun surgical treatments altogether.