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[Selective reporting of positive outcomes in randomised trials--secondary publication.. A comparison of protocols
Asbjørn Hróbjartsson1, An-Wen Chan, Mette T Haahr
1H:S Rigshopitalet, Det Nordiske Cochrane Center, University Health Network Toronto, Department of Medicine. a.hrobjartsson@cochrane.dk
Introduction:
Selective reporting of positive outcomes is associated with bias.
Materials And Methods:
We conducted a cohort study of 102 protocols of randomised trials approved by the Scientific Ethics Committees for Copenhagen and Frederiksberg in 1994-1995 and the corresponding 122 reports.
Results:
The median proportion of incompletely reported outcomes per trial was 50%. Statistically significant outcomes were more often fully reported, odds ratio 2.4. In 62% of trials, at least one primary outcome was changed.
Discussion:
Outcomes in randomised trials are often reported selectively.
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