44-55-66-PM, a mnemonic that improves retention of the Ottawa Ankle and Foot Rules: a randomized controlled trial

Studies have suggested that poor knowledge of the Ottawa Ankle Rules (OAR) limits its clinical impact. This study evaluated the ability of a mnemonic to improve knowledge of the OAR.

This was a single-blind randomized controlled trial performed among residents and medical students doing a pediatric emergency medicine rotation. At baseline, all participants were tested for their baseline knowledge of the OAR. The intervention was a standardized information sheet providing a mnemonic of the OAR (44-55-66-PM), while control subjects received its classic description. Block randomization (medical student vs. type of resident) was used. Each participant answered the same questionnaire at the end of rotation (3 weeks later) and via a Web-based survey 5 to 9 months postrandomization. Main outcome measures were knowledge of the components of the ankle rule based on a 13-item criterion grid and the foot rule based on a 10-item criterion grid. All questionnaires were marked at the end of the study by two reviewers blinded to the randomization. Discrepancies in final scores were resolved by consensus. Student's t-test was performed to compare mean scores on the evaluation between groups using an intention-to-treat approach.

Among the 206 eligible participants, 96 medical students and 94 residents were recruited and agreed to participate. Primary outcomes were measured in 95% of the participants at 3 weeks postrandomization and in 72% on the long-term follow-up. Participants in both groups were similar with regard to baseline characteristics and prior knowledge of the OAR. Both groups showed improvement in their knowledge of the rule during the study period. At mid-term, knowledge of the OAR was similar for the ankle components (score for mnemonic 10.9; control 10.2; 95% confidence interval [CI] for difference = -0.3 to 1.7) and for the foot (mnemonic 7.6 vs. control 7.5; 95% CI for difference = -0.7 to 0.9). On the long term, randomization to the mnemonic was associated with a better knowledge of the OAR as demonstrated by a higher score for the ankle component (mnemonic 10.1 vs. control 8.9; 95% CI for difference = 0.6 to 1.8) and for the foot (mnemonic 7.8 vs. control 6.5; 95% CI for difference = 0.8 to 1.9).

Mid-term knowledge of the OAR drastically improved for all participants of the study. The use of the mnemonic 44-55-66-PM was associated with a better long-term knowledge of the OAR among medical students and residents. The improvement in knowledge of the OAR among the control group highlights the importance of using controlled trials for studies evaluating knowledge transfer.