Evidence based healthcare has taken root as one of the central pillars of modern medicine. Arguably, the delivery of healthcare based on evidence has never been more important as we grapple with unexplained variations in practice and spiralling healthcare costs. But despite its widespread acceptance as a mechanism for rational decision making, evidence based healthcare remains in many ways an ideal rather than a fully fledged reality. On top of its well rehearsed limitations,1 new challenges are undermining its potential to improve healthcare outcomes.

First though, let us acknowledge the progress that has been made since evidence based medicine was first articulated in the early 1990s.2 Systematic review was then in its infancy, and methods for searching, selecting, and meta-analysing data have advanced almost beyond recognition. Our expectations of the quality of reporting for clinical trials and other study designs have risen sharply thanks to the widespread adoption of checklists, such as those created …