title: Teaching of evidence-based medicine to medical students in Mexico: a randomized controlled trial.
abstract: BACKGROUND
  Evidence-Based Medicine (EBM) is an important competency for the healthcare professional. Experimental evidence of EBM educational interventions from rigorous research studies is limited. The main objective of this study was to assess EBM learning (knowledge, attitudes and self-reported skills) in undergraduate medical students with a randomized controlled trial.
  
  
  METHODS
  The educational intervention was a one-semester EBM course in the 5th year of a public medical school in Mexico. The study design was an experimental parallel group randomized controlled trial for the main outcome measures in the 5th year class (M5 EBM vs. M5 non-EBM groups), and quasi-experimental with static-groups comparisons for the 4th year (M4, not yet exposed) and 6th year (M6, exposed 6 months to a year earlier) groups. EBM attitudes, knowledge and self-reported skills were measured using Taylor's questionnaire and a summative exam which comprised of a 100-item multiple-choice question (MCQ) test.
  
  
  RESULTS
  289 Medical students were assessed: M5 EBM=48, M5 non-EBM=47, M4=87, and M6=107. There was a higher reported use of the Cochrane Library and secondary journals in the intervention group (M5 vs. M5 non-EBM). Critical appraisal skills and attitude scores were higher in the intervention group (M5) and in the group of students exposed to EBM instruction during the previous year (M6). The knowledge level was higher after the intervention in the M5 EBM group compared to the M5 non-EBM group (p<0.001, Cohen's d=0.88 with Taylor's instrument and 3.54 with the 100-item MCQ test). M6 Students that received the intervention in the previous year had a knowledge score higher than the M4 and M5 non-EBM groups, but lower than the M5 EBM group.
  
  
  CONCLUSIONS
  Formal medical student training in EBM produced higher scores in attitudes, knowledge and self-reported critical appraisal skills compared with a randomized control group. Data from the concurrent groups add validity evidence to the study, but rigorous follow-up needs to be done to document retention of EBM abilities.
authors.affiliation: Department of Medical Education, UNAM Faculty of Medicine, Mexico City, Mexico. melchorsm@gmail.com
authors.forename: Melchor
authors.initials: M
authors.lastname: Sánchez-Mendiola
authors.forename: Luis F
authors.initials: LF
authors.lastname: Kieffer-Escobar
authors.forename: Salvador
authors.initials: S
authors.lastname: Marín-Beltrán
authors.forename: Steven M
authors.initials: SM
authors.lastname: Downing
authors.forename: Alan
authors.initials: A
authors.lastname: Schwartz
mesh_terms: D000337:Aerospace Medicine / Q000193:education; D002983:Clinical Competence; D018592:Cross-Over Studies; D003479:Curriculum; D003906:Developing Countries; D004504:Education, Medical, Undergraduate; D004521:Educational Measurement; D019317:Evidence-Based Medicine / Q000193:education*; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007396:Internship and Residency; D008297:Male; D008800:Mexico; D008887:Military Medicine / Q000193:education; D012577:Schools, Medical; D011795:Surveys and Questionnaires; D055815:Young Adult