Assessment of medical students' knowledge retention in a diagnostic radiology course: lecture attendees versus absentees.

INTRODUCTION To compare class attendees versus absentees in their ability to retain knowledge during a diagnostic radiology course. MATERIALS AND METHODS This study recruited 146 fourth-year medical students who attended a diagnostic radiology course from February 2004 to June 2004. Eight unit tests were conducted. Questions for each test covered content taught in the prior class. Another examination (which students were not aware of beforehand) was conducted in June, and the questions for this examination included content from all lectures in the course. The class attendance rates were measured separately 6 times during the course. Students who were present on the last of these dates were categorised as attendees (group A students) and those who were absent were categorised as absentees (group B). RESULTS The average class attendance was 76.8% and the lowest attendance was 56.8%. For the unit tests, the average score of group A students (80.7 +/- 7.3) was significantly higher than that of the group B students (76.2 +/- 8.8) (P = 0.001). However, in the unanticipated examination, there was no significant difference in the scores between group A (68.1 +/- 10.3; range, 36-92) and group B students (65.5 +/- 13.5; range, 28- 88) (P = 0.19). Self-learning time was related to the unit test scores (P = 0.001) but not to the unanticipated examination scores (P = 0.27). CONCLUSION Students who frequently attend classes or study for longer can retain their knowledge over a short period of time, but there is no difference in knowledge retention between class attendees and absentees at the end of a 4-month course.