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Table 1 Comparisons of percent 'yes' and percent 'differences' using the enhanced Overview Quality Assessment Questionnaire (OQAQ).

From: Does updating improve the methodological and reporting quality of systematic reviews?

Questions OQAQ

Original Reviews yes, % reviews yes

[95% CI]

Updated Reviews yes, % reviews yes

[95% CI]

Difference % Yes

[95% CI] p-value

1. Were the search methods used to find evidence reported?

81% [68.9 to 93.4]

87% [75.7 to 97.9]

5.7% [-6.6 to 17.9] 0.43

2. Was the search strategy for evidence reasonably comprehensive?

68% [47.0 to 88.7]

70% [48.3 to 91.3]

1.9% [-19.0 to 22.8] 0.83

3. Were the criteria used for deciding which studies to include in the overview reported?

98% [94.4 to 100.0]

91% [80.5 to 100.0]

-7.6% [-11.2 to 3.9] 0.09

4. Was bias in the selection of studies avoided?

64% [45.4 to 82.8]

70% [52.0 to 87.6]

5.7% [-13.1 to 24.4] 0.53

5. Were criteria used for assessing validity of the included studies reported?

89% [73.7 to 100.0]

96% [85.9 to 100.0]

7.6% [-7.4 to 22.5] 0.14

6. Was the validity of all studies referred to in the text assessed using appropriate criteria (either in selecting studies for inclusion or in analyzing studies that are cited)?

85% [70.6 to 99.2]

93% [82.9 to 100.0]

7.6% [-0.68 to 21.9] 0.22

7. Were methods used to combine the findings of relevant studies (to reach a conclusion) reported?

89% [66.2 to 99.8]

83% [71.5 to 100.0]

-5.7% [-022.9 to 11.6] 0.40

8. Were findings of the relevant studies combined appropriately relative to the primary question addressed?

87% [68.4 to 100.0]

91% [78.7 to 100.0]

3.8% [-14.6 to 22.2] 0.54

9. Were the conclusions made by the author (s) supported by the data and/or analysis reported in the overview?

76% [63.8 to 87.2]

94% [88.1–100.0]

18.9% [7.2 to 30.6] 0.01

10. How would you rate the scientific quality of this overview?

4.70 [4.47 to 4.94]

4.81 [4.59 to 5.04]

0.11 [-.28 to .70] 0.52