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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”
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Systematic Reviews

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