Effects of spaced learning on knowledge acquisition, knowledge retention, and learning-related anxiety in health professions education: A systematic review and meta-analysis of randomized controlled trials

The evolving demands of health education necessitate the integration of innovative approaches that enhance students' knowledge retention, support learning motivation, and improve pedagogical effectiveness. Spaced learning, defined as an instructional approach in which learning content is distributed across repeated sessions separated by predetermined time intervals, has received increasing attention because of its potential to enhance knowledge acquisition, promote long-term memory consolidation, and reduce learning-related anxiety.

This systematic review and meta-analysis aimed to quantitatively evaluate the effects of the spaced learning method on knowledge acquisition, knowledge retention, and learning-related anxiety among students in health professions education.

A systematic search of the Web of Science, Cochrane Library, SpringerLink, ScienceDirect, PubMed, Scopus, ProQuest, EBSCOhost/CINAHL Complete, and MEDLINE databases was conducted up to May 2025 without publication year restrictions. The literature screening and data extraction processes were carried out independently by two researchers. A total of nine randomized controlled trials (RCTs) met the eligibility criteria and were included in the systematic review and meta-analysis. The methodological quality of the included studies was assessed using the Cochrane Collaboration's Risk of Bias (RoB 2.0) tool. The study was reported in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, and the meta-analysis was conducted using Comprehensive Meta-Analysis (CMA) Version 3 software.

Nine RCTs met the eligibility criteria and were included in the systematic review and meta-analysis. The spaced learning intervention demonstrated statistically significant and positive effects on knowledge acquisition (Hedges' g = 0.69; 95% CI: 0.51-0.88), knowledge retention (Hedges' g = 0.62; 95% CI: 0.43-0.82), and learning-related anxiety (Hedges' g = 0.90; 95% CI: 0.44-1.36) (p < 0.001). Subgroup analyses identified statistically significant beneficial effects within the examined professional groups and intervention-duration categories; however, formal between-subgroup comparisons were not performed.

Spaced learning appears to be a promising educational strategy that positively influences knowledge acquisition, knowledge retention, and learning-related anxiety among students in health professions education. However, given that the included studies were assessed as having a high overall risk of bias, these findings should be interpreted with caution. Further high-quality, methodologically robust studies are needed to confirm the strength and consistency of these effects.