Table 4.

Summary of articles focused on frequency

Citation	Study design	Participants	Intervention	Key findings
Kerfoot BP et al. 2007	RCT to determine if spacing principles can improve acquisition and retention of medical knowledge	Five cohorts with 76 to 80 urology residents in each cohort	Frequency: multiple vs single	Conclusive evidence to support repetitive, spaced education in online learning, since residents in the spaced education cohort demonstrated significantly greater online test scores than those in the bolus cohort. The scores for the spaced cohort remained stable with no overtime, while test scores in the bolus cohort demonstrated a significant linear decrease.
		Of 537 participants, 400 (74%) completed the online staggered tests and 515 (96%) completed the In-Service Examination	Technique: self-directed
		Cohort 1 = bolus, single intervention; Cohort 2 = multiple, spaced intervention	Media: Internet-based
		Country: USA and Canada	Cohort 1 received bolus education of 96 study questions (June 2005); Cohort 2 received daily emails over 27 weeks (June to December 2005), each with one to two questions in spaced pattern. In November 2005, all participants completed the urology exam. Participants were randomized to five cohorts and completed a 32-item online test at staggered time points (1 to 14 weeks) after completion of Spaced Education.
Kerfoot BP et al. 2009	RCT to determine if Spaced Education is an effective form of CME	Urologists and urology residents	Frequency: multiple vs single	Conclusive evidence to support the use of ISE programmes. Knowledge scores of ISE intervention were statistically significantly higher than those of the control bolus method.
		Completed by 71% of urologists and 83% of residents	Technique: self-directed
		Cohort 1 = 80 urologists, 160 residents, completed by 196; Cohort 2 = 80 urologists, 160 residents, completed by 182	Media: Internet-based
		Country: USA (March to July 2007)	A total of 160 urologists and 320 urology residents were randomized to one of two cohorts. Participants were stratified by training level (urologist in practice vs resident) and urology training year (residents only) and were block randomized (block size = 8) to one of two cohorts. Participants in Cohort 1 received the 3-cycle ISE course on the HP CPGs, with 24 control items on the SIA CPGs in cycle 3. Participants in Cohort 2 received the 3-cycle ISE course on SIA CPGs, with 24 control items on HP CPGs in cycle 3. The trial was structured in this manner to allow the topic-specific learning gains from the ISE courses to be identified in cycle 3. Since the 24 items are presented simultaneously to both cohorts in cycle 3, the learning gains of physicians who had completed two cycles of the ISE programme could be directly compared with those physicians who were presented with the material for the first time (controls).
Kerfoot BP et al. 2010	RCT to determine if Spaced Education can effect knowledge transfer and the ability to make diagnostic decisions	Urology residents	Frequency: multiple vs single	Conclusive evidence to support spaced, web-based education compared to WBT. Spaced education demonstrated a statically significant increase in knowledge and long-term retention of knowledge compared with bolus web-based modules that delivered the same content of histopathology diagnostic skills.
		Cohort 1 = 164; Cohort 2 = 194	Technique: self-directed
		Country: USA (June 2007 to June 2008)	Media: Internet-based
			Transfer and retention of diagnostic skills between Spaced Education vs bolus, WBT
			All residents were sent both spaced education and WBT, but the set of topics delivered by each method varied by cohort. Residents in Cohort 1 received three cycles of spaced education on prostate-testis (weeks 1 to 4, 5 to 8, and 13 to 16) and three WBT modules on bladder-kidney (weeks 14 to 16). Residents in Cohort 2 received three cycles of spaced education on bladder-kidney (weeks 1 to 4, 5 to 8, and 13 to 16) and three WBT modules on prostate-testis (weeks 14 to 16). The spaced education items were delivered each weekday through emails containing one question/answer, and the spaced education material was distributed in three cycles or repetitions to take advantage of the spacing effect. The WBT used the identical content and delivery system, with the questions aggregated into three 20-question modules delivered through separate emails in week 14. The trial was specifically structured to ensure that within a given set of topics (bladder-kidney or prostate-testis) the only difference between intervention cohorts was the spacing of content.

CME Continuing medical education, CPG Clinical practice guideline, HP Haematuria and priapism, ISE Interactive spaced education, RCT Randomized controlled trial, SIA Staghorn calculi, infertility, and antibiotic use, WBT Web-based teaching.