the metablog

Posts tagged Evidence based medicine.

The importance of non-inferiority and equivalence

Three papers from the first BJA of the new decade highlight the importance of non-inferiority: protective ventilation strategies, dexamethasone for prolonging interscalene blocks, and high inspired oxygen and surgical site infections.

Although none investigated new questions, they all represent studies into areas of ongoing uncertainty. They are each a useful reminder that most perioperative interventions do not significantly improve outcomes, although the majority of these probably do not ever make it to publication.

Lung-protection and atelectasis

Généreux et al. investigated the atelectasis-preventing benefit of a common protective ventilation strategy (PEEP and regular recruitment manoeuvres). Notable not just because there was no difference in atelectasis after extubation, but because the use of ultrasound to measure atelectasis helped to better track the intraoperative and post-extubation changes between the intervention and control groups. [→ article summary]

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Small Changes & Protection: antihypertensives, cognitive decline and ischaemic preconditioning

Metajournal on Small Changes & Protection: antihypertensives, cognitive decline and ischaemic preconditioning

Three interesting articles that appeared in the past few months, all following a common theme of ‘protection with small changes’. Although only one is itself practice changing, together they challenge us to continue to look to how small practice changes may have significant protective and preventative effects in the lives of our patients.

Antihypertensives evening dosing

Hermida et al. (2019) published impressive results from the massive, 10-year Hygia Project, which randomised almost 20,000 patients to take anti-hypertensive medications at bedtime or awakening.

Not only did patients who took antihypertensives (of any class) in the evenings have better blood pressure control, they also received a 45% reduction in major cardiovascular outcomes, including CVD death, infarct, coronary revascularisation, heart failure and stroke!

Given that many critical care doctors briefly touch on the medications their patients are taking, a simple “you should ask your primary physician about when its best to take your blood pressure tablets” could have a disproportionately large impact on patient health.

Read on for protection with intravenous lidocaine and ischaemic conditioning...

Ketamine, Checklists and Social Media

Metajournal on Ketamine, Checklists and Social Media with ice-cream

As I read articles this week, three very different papers created a nexus of interest and push-back against mildly dogmatic thinking in the critical care specialities. Two challenge existing anaesthesia dogma, while the third highlights the potential for missteps when incorporating new media into our practice and education.

Although critical care specialties like anaesthesia and emergency medicine are often seen from the outside as embracing change and being unafraid of dipping our collective toes into the rivers of progress, there are still many strongly held views that persist even in the face of contrary evidence.

Ketamine and persistent pain

Chumbley, Thompson, Swatman and Urch report in the European Journal of Pain the results of their double-blind, randomised, placebo-controlled trial of a 96-hour perioperative ketamine infusion to reduce persistent post-surgical pain after thoracotomy. Notably they found that this significant-duration ketamine infusion did not reduce post-thoracotomy chronic pain.

This paper is the first quality RCT to follow thoracotomy patients for a year after surgery in the setting of perioperative ketamine. It adds to existing evidence suggesting a lack of effect of ketamine for mitigating persistent surgical pain – even though this has been a popular opinion (hope?) among anaesthetists and pain specialists in the past. The results of the ROCKet trial will provide us with more confidence in answering this question.1

Read on for anaesthesia checklists and FOAMed mistakes...


  1. A collection of related articles can be found here: Does ketamine reduce persistent post-surgical pain? 

The 4th Horseman: Research Fraud & Mountains of Fujii

The fourth and final horseman of the medical research apocalypse is the scourge of medical research fraud. Although certainly not a new problem, the scale and potential impact of research deceit is unlike anything faced previously.

Academic fabrication, falsification, and plagiarism (FFP) make up the breadth of academic fraud – and sadly, anesthesia is the number one specialty by volume. In 2012 our eyes were opened to the sheer scale of the problem as the largest medical research fraud in history was exposed.

Trust, responsibility and the Fujii fraud

Medical research involves a lot of trust. The trust of patients and the public, the trust of publishers and the trust of the research-consuming clinician. Unfortunately we often overlook our responsibility to ensure that our trust is not misused.

"...with increasing amazement, we notice that the results reported by Fuji et al. are incredibly nice ..." wrote Kranke, Apfel and Roewer in their April 2000 letter, politely challenging Yoshitaka Fujii's PONV research.1

And so began the very slow unravelling of the biggest academic fraud in the history of medicine. Despite a meaningless response from Fujii to that first challenging letter, there was no investigation or further questioning from the various anesthesia journals. In fact Anesthesia & Analgesia went on to publish another 11 articles by Fujii over the next decade.2,3

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  1. Kranke P, Apfel CC, Roewer N, Fujii Y. Reported data on granisetron and postoperative nausea and vomiting by Fujii et al. Are incredibly nice! Anesth Analg. 2000 Apr;90(4):1004-7. 

  2. To their credit A&A were instrumental in ultimately uncovering the fraud and have lead the charge in undoing the damage inflicted by Fujii. Shafer SL. Fujii Statement Of Concern. Anesth Analg. 2012 Mar 7. 

  3. Yentis SM. Lies, damn lies, and statistics. Anaesthesia. 2012 May;67(5):455-6. 

The 3rd Horseman: Significance & Relevance

Arguably the most important piece of the evidence-based-medicine puzzle is when we ask ourselves:
"Is this evidence significant? – Is this relevant to my patients and my practice?"

When we talk about the 'quality' of a published research work we largely mean what the epidemiologists refer to as 'internal validity' – the extent to which the study's conclusions are actually warranted given the methodology and results. Internal validity looks only at the study design, conduct and interpretation, and takes into account bias and confounders. While important, internal validity is not alone sufficient.

The significance of a piece of evidence to medicine in general, along with it's relevance to our own practice, is referred to as the external validity. I think that for your and my practice this is often what matters most.

Really, external validity just describes how well the results and conclusions can be generalized to situations and people beyond those in the study.

I think of significance as the cumulative generalizability of a piece of evidence for the specialty and for wider medicine, integrated with how well the evidence agrees with what is already known. Relevance describes how applicable the evidence is to my hospital, my practice – and my patients.

It has significance for you, and relevance for me.

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