Kieran Walsh: Cardiac arrests, catholic priests, and evidence-based clinical decision support

I used to work in a hospital that was run by nuns. Priests also had a role but they were very much in second place. The main job of the priest was to give last rites at cardiac arrests. Catholic priests give last rites to people who are dying—to cleanse them of their sins. Some of the priests were good runners and would arrive at the arrest before the doctors. I always worried about giving electric shocks when holy oils were close at hand but never had the courage to ask the priest if the oils were flammable.

On the plus side, it was often a great comfort to relatives that their loved one had received the last rites before they died. I was always glad to see the priest—I knew it would make for a less painful conversation later. But some of my colleagues were unconvinced. In the doctor’s mess afterwards, one of my registrars said that he thought that the last rites were all a bit of a waste of time. In turn I wondered about our efforts as doctors and the evidence base for cardiopulmonary resuscitation. But I didn’t say it out loud as I thought it might be blasphemy.

I still wonder about the evidence base for cardiopulmonary resuscitation. And it turns out that much of what we used to do and still do during cardiac arrests is based on shaky evidence. For example there is little evidence that giving drugs during a cardiac arrest improves survival. [1] There is also weak evidence on the effectiveness of advanced airway management. [1] But we still keep giving these treatments, and guidelines continue to recommend them—at least until better evidence comes along.

And how will we know when we have better evidence? The GRADE system (Grading of Recommendations, Assessment, Development and Evaluations) is our best hope at the moment. [2] GRADE is a widely adopted tool for grading the quality of evidence. GRADE looks at a number of criteria including risk of bias, imprecision, inconsistency, indirectness and publication bias to judge quality.

To look at one aspect, knowing whether or not there is publication bias has always puzzled me. How can you tell if there is publication bias if you don’t know of all the papers that have not been published?

According to GRADE, if you find lots of small studies that have been funded by industry and that all have positive results and that have been published in the early phase of interest in a field, then publication bias is screaming at you. This is because positive studies are associated with industry funding and both are associated with publication bias. Also negative studies are harder to get published and so tend to be published later.

This is just one aspect of GRADE—you can find out more here on our new evidence based medicine toolkit on BMJ Best Practice.

Good evidence will emerge in the end—we have just got to be patient and “keep the faith”. This might not be evidence based but the priests would like it.

Kieran Walsh is clinical director of BMJ Learning and BMJ Best Practice. He is responsible for the editorial quality of both products. He has worked in the past as a hospital doctor—specialising in care of the elderly medicine and neurology.

Competing interests: Kieran Walsh works for BMJ, which produces the online clinical decision support tool BMJ Best Practice.


  1. AHA MF. 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2015;132:S1.
  2. Guyatt GH, Oxman AD, Vist GE, Kunz R, Falck-Ytter Y, Alonso-Coello P, Schünemann HJ. Rating quality of evidence and strength of recommendations: GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ: British Medical Journal. 2008 Apr 26;336(7650):924.