| Ref ID | 471 |
| First Author | J. J. Kirkham |
| Journal | BMJ |
| Year Of Publishing | 2010 |
| URL | https://www.bmj.com/content/bmj/340/bmj.c365.full.pdf |
| Keywords |
• Cochrane • Multiplicity • Missing data • General medical |
| Problem(s) |
• Multiplicity of outcomes and lack of pre-specification for outcome reporting • Failure to address missing outcome data in analyses • Weaknesses identified in some Cochrane reviews |
| Article Type | Empirical |
| Article Subtype | Meta-epidemiological analysis |
| First Author Country | United Kingdom |
| Aim | To assess the prevalence of outcome reporting bias (the selection for publication of a subset of the original recorded outcome variables on the basis of the results) and its impact on Cochrane reviews published between 2006-2007. A sensitivity analysis was undertaken to assess the impact of outcome reporting bias on reviews that included a single meta-analysis of the review primary outcome. |
| Level of Investigation | Analytical |
| Summary of Findings | 55% of the included reviews did not include full data for the review primary outcome of interest from all eligible trials. 34% of included reviews contained at least one trial with high suspicion of outcome reporting bias for the review primary outcome. In a sensitivity analysis of the primary outcome of interest, the treatment effect estimate was reduced by 20% or more in 23% of reviews. Of the meta-analyses with a statistically significant result 19% became non-significant after adjustment for outcome reporting bias and 26% would have overestimated the treatment effect by 20% or more. |
| Number of systematic reviews included | 283 |
| Number of eligible systematic reviews assessed | 309 |
| Treatment impacted | Yes |
| Treatment impacted description | |
| Interpretation impacted | Yes |
| Interpretation impacted description | Nearly a fifth of statistically significant meta-analyses of the review primary outcome were affected by outcome reporting bias and a quarter would have overestimated the treatment effect by 20% or more |