What is the Peto Odds Ratio due to zero events in one trial?
The Peto Odds Ratio is a measure of effect size that is used to compare treatments in clinical trials. It is calculated as the ratio of the odds of an event occurring in the treatment group to the odds of an event occurring in the control group. In cases where there are zero events in one of the trial groups, the Peto Odds Ratio may be downgraded by one increment due to heterogeneity, as indicated by the I2 statistic. This is referenced in the Chronic Heart Failure Treating Heart Failure NICE 2018 guideline, where it states that the Peto Odds Ratio was downgraded by one increment due to heterogeneity, I2=59%, which was unexplained by subgroup analysis.