Background: The time course of physicians' knowledge retention after learning activities has not been well characterized. Understanding the time course of retention is critical to optimizing the reinforcement of knowledge.
Design: Educational follow-up experiment with knowledge retention measured at 1 of 6 randomly assigned time intervals (0-55 days) after an online tutorial covering 2 American Diabetes Association guidelines.
Participants: Internal and family medicine residents.
Measurements: Multiple-choice knowledge tests, subject characteristics including critical appraisal skills, and learner satisfaction.
Results: Of 197 residents invited, 91 (46%) completed the tutorial and were randomized; of these, 87 (96%) provided complete follow-up data. Ninety-two percent of the subjects rated the tutorial as "very good" or "excellent." Mean knowledge scores increased from 50% before the tutorial to 76% among those tested immediately afterward. Score gains were only half as great at 3-8 days and no significant retention was measurable at 55 days. The shape of the retention curve corresponded with a 1/4-power transformation of the delay interval. In multivariate analyses, critical appraisal skills and participant age were associated with greater initial learning, but no participant characteristic significantly modified the rate of decline in retention.
Conclusions: Education that appears successful from immediate posttests and learner evaluations can result in knowledge that is mostly lost to recall over the ensuing days and weeks. To achieve longer-term retention, physicians should review or otherwise reinforce new learning after as little as 1 week.