The choice of summary statistics for meta-analyses of rare events caused controversy (about whether the Peto odds ratio should be reported instead of risk differences) when it led to conflicting findings from two systematic reviews examining the risk of cardiovascular side effects associated with varenicline use.71 72 We present results using both measures: a relative measure (Peto odds ratio and sensitivity analyses with fixed and random effects odds ratios) as well as an absolute measure (risk difference). Findings were consistent for all examined outcomes.
