A decision tool to help researchers make decisions about including systematic reviews in overviews of reviews of healthcare interventions

Table 1 Comprehensiveness of different inclusion scenarios

Inclusion scenario	Amount of outcome data lost of changed per overview (%)
Inclusion scenario	Acute asthma	Acute otitis media	Bronchiolitis	Croup	Eczema	Gastroenteritis	Procedural sedation
Full inclusion scenario (include all Cochrane and non-Cochrane SRs)	0	0	0	0	0	0	0
First restricted scenario (include only Cochrane SRs)	28	54	13	0	67	31	0
Second restricted scenario (include all non-overlapping SRs and select the Cochrane SR for groups of overlapping SRs)	4	39	13	0	39	31	Unknown^a
Third restricted scenario (include all non-overlapping SRs and select the most recent SR for groups of overlapping SRs)	12	39	13	0	48	34	Unknown^a
Fourth restricted scenario (include all non-overlapping SRs and select the highest quality SR for groups of overlapping SRs)	4	Unknown^a	13	0	Unknown^a	31	Unknown^a

^aUnable to calculate amount of outcome data loss and change because data for the comparator groups were often not available (procedural sedation overview) or because multiple systematic reviews were tied for “highest quality” (fourth restricted scenario)
Modified from Pollock et al. [9]

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