EBM at the bedside-bicuspid aortic valves and familial screening
The original proponents of EBM have always argued for “evidence at the bedside” so that we can make the best decisions for patients nearest to the point “where the rubber hits the road”. How often do we clinicians actually look up the evidence in real time during or soon after a consultation to change the management or the advice we give to a patient?
I saw a lady in her 40s in our cardiology clinic this week. She has been followed up every 1-2 years in clinic for bicuspid aortic valve (BAV). Basically, the aortic valve is at the outflow of the left ventricle (the major pump of the heart) and usually has three cusps which open and close to ensure flow of blood in the right direction through and out of the heart. In bicuspid valves, people are born with only two cusps and over their lifetime, they are more prone to developing narrowing of the valve (“aortic stenosis”), with a significant probability of needing aortic valve replacement during their lifetime. The idea of screening and surveillance is that any narrowing or malfunction of the aortic valve can be picked up early, and the person can be referred for surgery more quickly and effectively than if their disease had progressed.
BAV is the most common abnormality of the heart valves, occurring in 1- 2% of the general population and is twice as common in males as in females. Reassuringly, a recent cohort study of patients with BAV found that they have similar survival rates to the normal population. However, “given that serious complications will develop in over a third of patients with BAV, the bicuspid valve may be responsible for more deaths and morbidity than the combined effects of all the other congenital heart defects”. The potential problems are narrowing or leaking of the aortic valve, infective endocarditis and enlargement or “dilatation” of the aorta. In other words, BAV is common, has serious complications and there is a treatment which improves survival (aortic valve replacement). Therefore, BAV is a condition which meets Wilson’s criteria for screening.
I was asked by the lady if her children were at risk of BAV and whether they should be screened. I did not know the exact answer so I looked online with the patient. There is a 30% risk of aortic dilatation or BAV in first degree relatives (parents, children or siblings) of people with BAV. A more recent study showed that 20% of first degree relatives of people with BAV may have undetected BAV themselves. It turns out there are no NICE guidelines or formal UK/European guidelines for whether we should be screening relatives or how we should be doing it.
Interestingly, across the pond, the Americans have guidelines for familial screening and the literature seems to suggest it. Therefore adult children of patients with BAV should have an echocardiogram to check that they do not have a BAV which would mean that they should also be followed up. Valvular heart disease is a bigger health issue than we imagine.
There are four take home messages for me. First, EBM can be done at the bedside-it is meant to be the most practical of clinical sciences. Second, there is no harm as a clinician in saying “I don’t know” and looking it up. Third, sometimes it is the obvious clinical questions which are still unanswered or debatable. Finally, practice can be changed.
Obesity: Inequalities in EBM, medical research and policy
Today’s main news story is that obesity is on the up and will continue to rise if coordinated action is not taken at local, national and international levels. A Lancet series of articles examines the evidence for the growing burden and cost of obesity globally and the policy steps needed to prevent 65 million more adults in the USA and 11 million more adults in the UK becoming obese by 2030. Successive governments have allowed the food industry to self-regulate and the evidence clearly suggests that this does not work, since the industry’s interest are profits.
What strikes me is that instructive lessons learned from a strikingly similar case-in-point over the last 60 years, namely the tobacco industry, are not being put into practice. There was good medical evidence for smoking and its detrimental effects of health since the work of Richard Doll and Austin Bradford Hill showed the link with lung cancer in the early 1950s, but it was not until 2005 that the World Health Organization adopted the Framework Convention for Tobacco Control, the world’s first and only public health treaty. Our policymakers smugly talk about tobacco as a tackled problem, but it was less than 10 years ago that UK policy started moving in the direction of smoke-free public places.
We have an obese body of evidence (pun intended) to show that the pathophysiology and epidemiology of obesity is bad for our health, and we have enough evidence to show that current methods of tackling industry problems are not working. Governments are quick to say that the food industry is different but what are the incentives for the food industry to behave differently? Is it going to be acceptable to wait 50-60 years before governments and global health policymakers put evidence into practice? Evidence-based medicine aims, at the end of the day, to institute changes which make the health of individuals better. It seems that there are inequalities in the way evidence is put into practice, based not just on societal interests, but on conflicts of interest, particularly multi-billion dollar industries. If we are serious about EBM and evidence-based policy, we should take lessons learned from other sectors and apply them accordingly.
EBM in critically unwell patients
Evidence based medicine (EBM) was undoubtedly one of the major medical advances of the last century. EBM is at its best when it changes daily clinical practice and challenges well-established norms, but this only really happens every now and then. Two recent New England Journal papers about management of critically unwell patients have done just that.
Since medical school, doctors learn that the optimal treatment of patients with severe infection (sepsis) and low blood pressure (shock) is to pour in intravenous fluids. Not something that is up for debate, you would think. There are much more pressing things like drug-eluting stents to take to clinical trials. Well, think again. A paper by Maitland and colleagues reports a trial in Africa where over 3000 children with severe sepsis and shock were randomised to receive either boluses of fluid (albumin and saline) or no bolus in the early stages of treatment. Children with malnutrition or gastroenteritis were excluded. Amazingly, any bolus treatment led to an increase of 45% in the risk of mortality at 48 hours (relative risk 1.45; 95% CI, 1.13 to 1.86; P=0.003). The results were consistent across all subgroups of patients, and now researchers and clinicians all over the world are scratching their heads to understand whether what they have been doing since they were medical students is actually wrong and too much fluid is a bad thing in septic patients.
Intensive care, like surgery, is often cited as a difficult area of medicine for EBM to infiltrate. The traditional mantra is to give ITU patients nutritional support as soon as possible. In a trial of nearly 5000 patients, the two arms were either early initiation of intravenous (also known as parenteral) nutrition on days 1 and 2 of ITU admission, or late initiation of parenteral nutrition after day 7. Late initiation was associated with reduced complications and faster recovery. So EBM is possible in the ITU and it does change practice. What other areas of treatment of the critically unwell do we need to test?