Meta-Analyze Dichotomous Data: Do the Calculations with Log Odds Ratios and Report Risk Ratios or Risk Differences

Easy SAS calculations for risk or prevalence ratios and differences.

We would like to make the readership aware that risk or prevalence ratios and differences, when they are the parameter of interest, can be directly calculated by using SAS software (SAS Institute, Inc., Cary, North Carolina). There is no longer any good justification for fitting logistic regression models and estimating odds ratios when the odds ratio is not a good approximation of the risk or ...

The relative merits of risk ratios and odds ratios.

When a study outcome is rare in all strata used for an analysis, the odds ratio estimate of causal effects will approximate the risk ratio; therefore, odds ratios from most case-control studies can be interpreted as risk ratios. However, if a study outcome is common, the odds ratio will be further from 1 than the risk ratio. There is debate regarding the merits of risk ratios compared with odds...

Noninferiority trial designs for odds ratios and risk differences.

This study presents constrained maximum likelihood derivations of the design parameters of noninferiority trials for binary outcomes with the margin defined on the odds ratio (ψ) or risk-difference (δ) scale. The derivations show that, for trials in which the group-specific response rates are equal under the point-alternative hypothesis, the common response rate, π(N), is a fixed design paramet...

Risk ratios and odds ratios--what are they?

A risk ratio (sometimes called relative risk, both abbreviated to RR) and an odds ratio (OR) are ways of expressing a comparison between two proportions. For example, in this paper, there are two randomised groups in the trial, women in the lateral position and women in the supported sitting position in the passive second stage of labour. The authors wanted to compare the proportions of instrum...

Relative Risk and Odds Ratios Examples