Prolonged delays for research training in medical school are associated with poorer subsequent clinical knowledge.

Background: Complementary degree programs and research training are important alternative tracks in medical school that typically interrupt the traditional MD curriculum.

Objective: Examine effects of such a break on clinical knowledge after reentry into the MD curriculum.

Design: Retrospective cohort study.

Participants: Three hundred and two graduates of Mayo Medical School.

Main Measurements: Compared years of delay between the second and third years of medical school with third year clerkship grades, National Board of Medical Examiner's (NBME) Subject Examinations, and United States Medical License Exam (USMLE) Step 2.

Main Results: 258, 13, and 31 students spent 0, 1, or > or = 3 years pursuing research between the second and third year. Baseline measures of knowledge before matriculation and before the third year were similar between groups. Whereas a 1-year delay had no significant effect, a > or = 3-year delay was associated with fewer clerkship honors and lower NBME Medicine, Pediatrics, and Psychiatry percentiles compared to no delay (all p < .05). Students with a > or = 3-year delay had a 77% reduction in the odds of honors in Medicine. For each year of delay beyond 3, students' third-year NBME Medicine, Neurology, Obstetrics and Gynecology, and Psychiatry scores decreased as did USMLE Step 2 scores (r = -.38 to -.50, p < .05).

Conclusions: Delays of > or = 3 years between the second and third years of medical school are associated with lower grades and scores on clinical knowledge tests. Further research is needed to determine the optimal timing of research training and develop effective interventions to facilitate reentry into the medical school curriculum.