Book review: The Doctor's Guide to Critical Appraisal

Title: The Doctor’s Guide to Critical Appraisal, 3^rd Ed (2012)

Authors: Narinder Gossall, Gurpal Gossall

Publisher: PasTest

This book is not an opinion piece and it holds no new information, but it is as important as any other book I have reviewed because it aims to narrow the gap between practice and evidence in medicine by teaching doctors the science of medical practice; in other words, how to recognise and weigh error, and objectively appraise the scientific evidence for clinical practice.

The map is not the territory

Another version of this saying is “Treat the patient, not the X-rays”, but try as we might, we still end up treating the X-rays, even when the evidence is to the contrary.

Clot filters

It seems I will never run out of examples of treatments that sound obviously effective in theory, fall into common use based on the strength of the biological mechanism, and yet they fail to show a significant benefit when put to the test. The story of the IVC filter is one of these.

Deep venous thrombosis (DVTs, clots) in the leg can dislodge, traveling up through the main vein in the pelvis and abdomen (inferior vena cava, IVC), through the heart and then embolise in the lungs (pulmonary embolus, PE), sometimes causing rapid death. An IVC filter is a wire cage placed in the IVC that snares clots that have broken free from the leg veins, before they can travel to the lungs. The device has been used for decades, but without much evidence of benefit, as this recent report tells us.