Differences between students in problem-based and lecture-based curricula measured by clerkship performance ratings at the beginning of the third year

Background: Problem-based learning (PBL) is being incorporated into more medical curricula, but its influence on subsequent clinical performance remains unclear Purpose: To determine if PBL leads to better scores for fund of knowledge or clinical problem-solving skills in required clerkships taken early in the 3rd year at Penn State College of Medicine. Methods: Data were collected from 6 class years, for clinical clerkship subscores completed during the first 4 months of the 3rd year, of students completing 1 or 2 years in a PBL or traditional track. Clerkship scores were analyzed as individual clerkships and as the average across clerkships for each student. Statistical analysis included a comparison of clerkship scores between the 2 tracks, using a 2-sample t test, and calculation of effect sizes. A multiple regression model was also employed to adjust for age, gender, race, preadmission grade point average, and Medical College Admission Test (MCAT). Results: Mean scores of individual clerkships taken by problem-based or lecture-based students differed significantly in some clerkships, but the effect size was small. The effect sizes for fund of knowledge for the 6 clerkships ranged from 0.20 to 0.41;for clinical problem-solving skills, they ranged from 0.26 to 0.39. These differences between the problem-based and lecture-based students were of the same magnitude as the difference at the start of medical school on the MCAT, namely d = 0.31. There was a trend toward higher effect sizes in students having 2 rather than 1 year of PBL, and in later iterations of the track. Conclusion: PBL effect size on students' scores for fund of knowledge and clinical problem-solving skills was small to moderate in various years.