Effect of family medicine residents on use of diagnostic investigations: in a rural community emergency department

To determine the effect of the presence of family medicine residents on the use of laboratory and imaging investigations in a rural emergency department (ED). A retrospective cross-sectional electronic chart audit was completed. Background characteristics, as well as type and number of ordered investigations, were compared between study groups. Strathroy Middlesex General Hospital in Strathroy, Ont, a rural community hospital that sees approximately 20 000 ED visits per year. A total of 2000 sequential ED visits, including adult and pediatric patients. The test group consisted of patients seen while a resident was present in the ED. The control group consisted of patients seen while no residents were present in the ED. Twenty-two distinct categories of common ED investigations were studied. There was no statistically significant difference between study groups for 19 of the 22 categories of investigations. There were significant differences in 3 categories: an increased number of D-dimer assays for patients seen while there were no residents in the ED (1.7% of patients vs 0.5% of patients, P = .03) and increased computed tomography and ultrasound imaging for patients seen while a resident was in the ED (4.8% vs 1.8%, P = .0012, and 5.3% and 1.7%, P < .001, respectively). These differences are likely not owing to resident involvement but are explained by a difference in test availability between groups. The study was underpowered for most categories of studied investigations. However, the trends demonstrated in this study suggest that the presence of family medicine residents in a rural community ED does not substantially affect the overall use of diagnostic investigations.