Comparison of a traditional systematic review approach with review-of-reviews and semi-automation as strategies to update the evidence

Table 3 Characteristics of studies missed by the review of reviews approach

Sample size	Subtype	Studies missed by the ROR search*
Sample size	Subtype	N	%
Interventions studied in one or more arm	Surgery	15	60
	Radiation therapy	15	60
	Ablative therapy	10	40
Comparators	Active treatment comparator	15	60
	Conservative treatment comparator	8	32
	No comparator	8	32
Study design	Randomized and non-randomized trials	1	4
	Observational studies	24	88
	Single arm studies or within-treatment comparisons^†	2	8
Year of publication	2014	3	12
	2015	6	24
	2016	7	28
	2017	8	32
	2018	1	4
Total		25^‖	100.0

*Studies may have multiple arms; percentages do not sum to 100
^†Single-arm studies (or within-treatment comparisons) were eligible only for ablative therapies
^‖The ROR approach missed a total of 26 eligible citations, which one was a companion study and one was the Fenton et al. review. The analysis is limited to the 25 primary studies
Abbreviations: N number, NA not applicable, RCT randomized controlled trial, ROR review of reviews

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