Evaluation of AMSTAR to assess the methodological quality of systematic reviews in overviews of reviews of healthcare interventions

Table 4 Distribution of result and conclusion assessments for Cochrane and non-Cochrane systematic reviews

Result and conclusion assessments	Distribution of responses n (%)		Difference between groups (p-value for Mann-Whitney U-test)
Result and conclusion assessments	Cochrane systematic reviews (n = 28^a)	Non-Cochrane systematic reviews (n = 43^a)	Difference between groups (p-value for Mann-Whitney U-test)
Results
Unfavourable	4 (14.3%)	0 (0.0%)	0.14
Neutral	14 (50.0%)	23 (53.5%)
Favourable	10 (35.7%)	20 (46.5%)
Conclusions
Negative-Strong	6 (21.4%)	1 (2.3%)	0.035^b
Negative-Weak	6 (21.4%)	7 (16.3%)
Neutral	3 (10.7%)	7 (16.3%)
Positive-Weak	7 (25.0%)	13 (30.2%)
Positive-Strong	6 (21.4%)	15 (34.9%)

^aTwenty-four systematic reviews (2 Cochrane, 22 non-Cochrane) were excluded from this analysis because they did not contain relevant outcome data; ^bConclusions of Cochrane systematic reviews were more likely to be “negative” and conclusions of non-Cochrane systematic reviews were more likely to be “positive”

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