Background: Health care professionals worldwide attend courses and workshops to learn evidence-based medicine (EBM), but evidence regarding the impact of these educational interventions is conflicting and of low methodologic quality and lacks generalizability. Furthermore, little is known about determinants of success. We sought to measure the effect of EBM short courses and workshops on knowledge and to identify course and learner characteristics associated with knowledge acquisition.

Methods: Health care professionals with varying expertise in EBM participated in an international, multicentre before–after study. The intervention consisted of short courses and workshops on EBM offered in diverse settings, formats and intensities. The primary outcome measure was the score on the Berlin Questionnaire, a validated instrument measuring EBM knowledge that the participants completed before and after the course.

Results: A total of 15 centres participated in the study and 420 learners from North America and Europe completed the study. The baseline score across courses was 7.49 points (range 3.97–10.42 points) out of a possible 15 points. The average increase in score was 1.40 points (95% confidence interval 0.48–2.31 points), which corresponded with an effect size of 0.44 standard deviation units. Greater improvement in scores was associated (in order of greatest to least magnitude) with active participation required of the learners, a separate statistics session, fewer topics, less teaching time, fewer learners per tutor, larger overall course size and smaller group size. Clinicians and learners involved in medical publishing improved their score more than other types of learners; administrators and public health professionals improved their score less. Learners who perceived themselves to have an advanced knowledge of EBM and had prior experience as an EBM tutor also showed greater improvement than those who did not.

Interpretation: EBM course organizers who wish to optimize knowledge gain should require learners to actively participate in the course and should consider focusing on a small number of topics, giving particular attention to statistical concepts.