Methods of Converting Effect Measures Used in Meta-analysis: A Narrative Review and A Practical Guide.


effect measures
author’s guide

How to Cite

Toubasi, A., Al-Sayegh, T., & Rayyan, R. (2023). Methods of Converting Effect Measures Used in Meta-analysis: A Narrative Review and A Practical Guide. High Yield Medical Reviews, 1(1).


The publication of meta-analyses has grown exponentially over the past 20 years. Well-designed and reported meta-analyses provide valuable information to clinicians and policymakers. However, researchers face several hurdles in the process of conducting meta-analyses. The analysis process is one of these obstacles, particularly when the included studies report their outcomes using different outcome measures. This study aims to provide authors and researchers with a guide that can help them overcome the struggle of incorporating different outcome measures into the analysis. This article also intends to serve as an author’s guide to the key methods used to convert effect measures, the assumptions required for that, and the hierarchy for using these methods.


Hozo SP, Djulbegovic B, Hozo I. Estimating the mean and variance from the median, range, and the size of a sample. BMC Med Res Methodol. 2005;5(1):1-10.

Wan X, Wang W, Liu J, Tong T. Estimating the sample mean and standard deviation from the sample size, median, range and/or interquartile range. BMC Med Res Methodol. 2014;14:1-13.

Luo D, Wan X, Liu J, Tong T. Optimally estimating the sample mean from the sample size, median, mid-range, and/or mid-quartile range. Stat Methods Med Res. 2018;27(6):1785-1805.

Higgins JPT, Deeks JJ. Selecting Studies and Collecting Data. In: Cochrane Handbook for Systematic Reviews of Interventions. ; 2008:151-185. doi:

Altman DG, Deeks JJ, Sackett DL. Odds ratios should be avoided when events are common. Bmj. 1998;317(7168):1318.

Pagano M, Gauvreau K. Principles of biostatistics. Brooks/Cole. In: Belmont. ; 2000.

Deeks JJ, Higgins JPT. Statistical algorithms in review manager 5. Statistical Methods Group of The Cochrane Collaboration. 2010;1(11).

Egger M, Smith GD. Principles of and Procedures for Systematic Reviews. In: Systematic Reviews in Health Care. John Wiley & Sons, Ltd; 2001:23-42. doi:

Woodward M. Epidemiology: Study Design and Data Analysis. Chapman & Hall/CRC; 1999.

Rothman KJ. Analysis of crude data. Modern epidemiology. Published online 1986.

Prasad K, Jaeschke R, Wyer P, Keitz S, Guyatt G, Group EBMTTW. Tips for teachers of evidence-based medicine: understanding odds ratios and their relationship to risk ratios. J Gen Intern Med. 2008;23:635-640.

Sinclair JC, Bracken MB. Clinically useful measures of effect in binary analyses of randomized trials. J Clin Epidemiol. 1994;47(8):881-889.

Shrier I, Steele R. Understanding the relationship between risks and odds ratios. Clinical Journal of Sport Medicine. 2006;16(2):107-110.

Zhang J, Kai FY. What’s the relative risk?: A method of correcting the odds ratio in cohort studies of common outcomes. JAMA. 1998;280(19):1690-1691.

Greenland S. Model-based estimation of relative risks and other epidemiologic measures in studies of common outcomes and in case-control studies. Am J Epidemiol. 2004;160(4):301-305.

McNutt LA, Wu C, Xue X, Hafner JP. Estimating the relative risk in cohort studies and clinical trials of common outcomes. Am J Epidemiol. 2003;157(10):940-943.

Parmar MKB, Torri V, Stewart L. Extracting summary statistics to perform meta‐analyses of the published literature for survival endpoints. Stat Med. 1998;17(24):2815-2834.

Williamson PR, Smith CT, Hutton JL, Marson AG. Aggregate data meta‐analysis with time‐to‐event outcomes. Stat Med. 2002;21(22):3337-3351.

Tierney JF, Stewart LA, Ghersi D, Burdett S, Sydes MR. Practical methods for incorporating summary time-to-event data into meta-analysis. Trials. 2007;8(1):1-16.

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Copyright (c) 2023 High Yield Medical Reviews