Related Experiment Video
Updated: May 6, 2026

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment
Published on: April 19, 2024
A model-based correction for outcome reporting bias in meta-analysis
John Copas1, Kerry Dwan, Jamie Kirkham
1Department of Statistics, University of Warwick, Coventry CV4 7AL, UK.
Abstract:
It is often suspected (or known) that outcomes published in medical trials are selectively reported. A systematic review for a particular outcome of interest can only include studies where that outcome was reported and so may omit, for example, a study that has considered several outcome measures but only reports those giving significant results. Using the methodology of the Outcome Reporting Bias (ORB) in Trials study of (Kirkham and others, 2010. The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews. British Medical Journal 340, c365), we suggest a likelihood-based model for estimating the effect of ORB on confidence intervals and p-values in meta-analysis. Correcting for bias has the effect of moving estimated treatment effects toward the null and hence more cautious assessments of significance. The bias can be very substantial, sometimes sufficient to completely overturn previous claims of significance. We re-analyze two contrasting examples, and derive a simple fixed effects approximation that can be used to give an initial estimate of the effect of ORB in practice.
Insights
Outcome reporting bias (ORB) in medical trials can significantly skew results. This study proposes a model to correct for ORB, showing that adjusted findings move towards the null, potentially overturning significance claims.
Area of Science:
- Medical Research Methodology
- Biostatistics
- Evidence Synthesis
Background:
- Selective outcome reporting is a known issue in medical trials.
- This bias can lead systematic reviews to omit studies with non-significant results for certain outcomes.
- Existing systematic reviews may overestimate treatment effects due to this bias.
Purpose of the Study:
- To develop a statistical model for estimating the impact of outcome reporting bias (ORB) on meta-analysis results.
- To quantify the effect of ORB on confidence intervals and p-values.
- To provide a method for correcting ORB in systematic reviews.
Main Methods:
- Utilized the methodology from the Outcome Reporting Bias (ORB) in Trials study.
- Developed a likelihood-based statistical model to estimate bias.
- Re-analyzed two contrasting examples of meta-analyses.
Main Results:
- Correcting for ORB shifts estimated treatment effects towards the null hypothesis.
- The bias can be substantial, potentially reversing conclusions of statistical significance.
- A simple fixed-effects approximation was derived for practical estimation of ORB effects.
Conclusions:
- Outcome reporting bias significantly impacts the reliability of meta-analyses.
- Adjusting for ORB leads to more conservative and accurate assessments of treatment efficacy.
- The proposed model and approximation offer tools to mitigate the effects of ORB in evidence synthesis.
More Related Videos
06:55Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index
Published on: January 8, 2020
04:35Development of an Individual-Tree Basal Area Increment Model using a Linear Mixed-Effects Approach
Published on: July 3, 2020
Related Concept Videos
Strategies for Assessing and Addressing Confounding
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
Mechanistic Models: Compartment Models in Individual and Population Analysis
Bias
In statistics, a sampling bias is created when a sample is collected from a population, and some members of the population are not as likely to be chosen as others (remember, each member...
Bias in Epidemiological Studies
Methods of Medium Optimization