Statistical methods used for secondary and additional outcomes
Fracture, Gustilo-Anderson fracture
REGRESSION
These analyses are designed to provide additional insight and support for the primary analysis and to assess whether the methodological choices we made had an undue effect on the results. In reporting, they will be sharply distinguished from the primary outcome. Additional sensitivity analyses will be conducted based on the following variables as baseline covariates: Gustilo-Anderson fracture type, OTA Open Fracture Classification for contamination, time from injury to first debridement, and method of fixation. We will make available the results of Fisher’s exact test on the 2 × 2 cross-tabulation of the reoperation binary outcome and the treatment assignment. This does not consider the observation time and thus is an independent statistical procedure and may yield different decisions than the primary prespecified analysis. We will also report the 95% confidence interval for the risk difference between the groups. Because this will be conducted by an independent regression (binomial regression with the identity link), these new findings may be statistically inconsistent with the main analysis. Thus, we will only report 95% confidence intervals, omitting The risk difference is interpretively important and may be useful in future meta-analytic studies. Intent-to-treat analysis is recommended but impossible when the primary outcome is missing. We will conduct exploratory regression of missingness and observation time, using the following predictors when appropriate: gender, severity of injury, cost of travel to clinic, and age.