Skip to main content

Table 2 Impact of the full and restricted inclusion scenarios on the comprehensiveness and results of overviews

From: The impact of different inclusion decisions on the comprehensiveness and complexity of overviews of reviews of healthcare interventions

Overviews and inclusion scenariosa Number of included SRs (% data loss) Number of intervention comparisons (% data loss) Number of primary studies included (% data loss) Number of subjects included (% data loss) Number of outcomes (L: % outcomes lost; C: % outcomes changed)
Primary Secondary Adverse effects Supplemental Overall
Overviews for which Cochrane SRs examined all relevant intervention comparisons
 Bronchiolitis
  Full scenario 7 (0%) 8 (0%) 29 (0%) 3526 (0%) 13 (0%) 15 (0%) 20 (0%) 48 (0%)
  Restricted scenario 1 4 (43%) 8 (0%) 26 (10%) 3294 (7%) L: 1 (8%)
C: 0 (0%)
L: 2 (13%)
C: 1 (7%)c
L: 2 (10%)
C: 0 (0%)
L + C: 6 (13%)
  Restricted scenario 2 Same as restricted scenario 1
  Restricted scenario 3 Same as restricted scenario 1
  Restricted scenario 4 Same as restricted scenario 1
 Croup
  Full scenario 6 (0%) 16 (0%) 53 (0%) 5181 (0%) 31 (0%) 19 (0%) 0 (0%) 50 (0%)
  Restricted scenario 1 4 (33%) 16 (0%) 50 (6%) 4717 (9%) L: 0 (0%)
C: 0 (0%)
L: 0 (0%)
C: 0 (0%)
L: 0 (0%)
C: 0 (0%)
L + C: 0 (0%)
  Restricted scenario 2 Same as restricted scenario 1
  Restricted scenario 3 Same as restricted scenario 1
  Restricted scenario 4 Same as restricted scenario 1
 Gastroenteritis
  Full scenario 15 (0%) 9 (0%) 114 (0%) 14,801 (0%) 6 (0%) 7 (0%) 22 (0%) 35 (0%)
  Restricted scenario 1 3 (80%) 9 (0%) 88 (23%) 11,147 (25%) L: 0 (0%)
C: 1 (17%)d
L: 1 (14%)
C: 1 (14%)c
L: 5 (23%)
C: 3 (14%)c
L + C: 11 (31%)
  Restricted scenario 2 Same as restricted scenario 1
  Restricted scenario 3 3 (80%) 9 (0%) 46 (60%) 6070 (59%) L: 0 (0%)
C: 1 (17%)d
L: 0 (0%)
C: 2 (29%)c
L: 6 (27%)
C: 3 (14%)c
L + C: 12 (34%)
  Restricted scenario 4 Same as restricted scenario 1
Overviews for which Cochrane SRs did not examine all relevant intervention comparisons
 Acute asthma
  Full scenario 13 (0%) 11 (0%) 56 (0%) 5527 (0%) 12 (0%) 29 (0%) 19 (0%) 16 (0%) 76 (0%)
  Restricted scenario 1 7 (46%) 9 (18%) 45 (20%) 4521 (18%) L: 2 (17%)
C: 1 (8%)b
L: 10 (35%)
C: 0 (0%)
L: 5 (26%)
C: 1 (5%)c
L: 2 (13%)
C: 0 (0%)
L + C: 21 (28%)
  Restricted scenario 2 9 (30.8%) 11 (0%) 50 (11%) 5023 (9%) L: 0 (0%)
C: 1 (8%)b
L: 1
C: 0 (0%)
L: 0 (0%)
C: 1 (5%)c
L: 0 (0%)
C: 0 (0%)
L + C: 3 (4%)
  Restricted scenario 3 9 (30.8%) 11 (0%) 49 (13%) 5006 (9%) L: 0 (0%)
C: 1 (8%)b
L: 1
C: 0 (0%)
L: 6 (32%)
C: 1 (5%)c
L: 0 (0%)
C: 0 (0%)
L + C: 9 (12%)
  Restricted scenario 4 Same as restricted scenario 2
 Acute otitis media
  Full scenario 15 (0%) 18 (0%) 135 (0%) 28,323 (0%) 6 (0%) 22 (0%) 13 (0%) 41 (0%)
  Restricted scenario 1 6 (60%) 10 (44%) 84 (62%) 21,907 (32%) L: 0 (0%)
C: 0 (0%)
L: 14 (64%)
C: 1 (5%)c
L: 4 (31%)
C: 3 (23%)cd
L + C: 22 (54%)
  Restricted scenario 2 8 (47%) 15 (17%) 117 (13%) 26,261 (7%) L: 0 (0%)
C: 0 (0%)
L: 9 (41%)
C: 1 (5%)c
L: 3 (23%)
C: 3 (23%)cd
L + C: 16 (39%)
  Restricted scenario 3 5 (67%) 18 (0%) 106 (21%) 23,122 (18%) L: 2 (33%)
C: 0 (0%)
L: 6 (27%)
C: 3 (14%)bc
L: 2 (15%)
C: 3 (23%)cd
L + C: 16 (39%)
  Restricted scenario 4 Unable to calculatee
 Eczema
  Full scenario 19 (0%) 27 (0%) 136 (0%) 794,014 (0%) 27 (0%) 25 (0%) 52 (0%)
  Restricted scenario 1 6 (68%) 7 (75%) 29 (79%) 11,418 (99%) L: 20 (74%)
C: 2 (7%)bc
L: 13 (52%)
C: 0 (0%)
L + C: 35 (67%)
  Restricted scenario 2 11 (42%) 22 (19%) 115 (17%) 697,014 (15%) L: 5 (19%)
C: 2 (7%)bc
L: 13 (52%)
C: 0 (0%)
L + C: 20 (39%)
  Restricted scenario 3 12 (42%) 27 (0%) 133 (15%) 792,721 (4%) L: 0 (0%)
C: 3 (11%)bcd
L: 22 (88%)
C: 0 (0%)
L + C: 25 (48%)
  Restricted scenario 4 Unable to calculatee
 Procedural sedation
  Full scenario 13 85 149,088
  Restricted scenario 1 0 (100%) 0 (100%) 0 (100%)
  Restricted scenario 2
  Restricted scenario 3
  Restricted scenario 4
  1. C outcome changed, L outcome lost, L+C outcome lost or changed, SR systematic review
  2. a Full scenario: include all Cochrane and non-Cochrane SRs; restricted scenario 1: include only Cochrane SRs; restricted scenarios 2–4: include all non-overlapping SRs, and in the case of overlapping SRs include the Cochrane SR (restricted scenario 2), the most recent SR (restricted scenario 3), or the highest quality SR (restricted scenario 4)
  3. bResult assessment changed from “favorable” or “unfavorable” to “neutral”
  4. cResult assessment changed from “unknown” to something else
  5. dResult assessment changed from “neutral” to “favorable” or “unfavorable”
  6. eTwo systematic reviews were tied for “highest quality”