Figure 3. Subgroup Analyses and Evaluation for Effect Modification.

Subgroup analyses were conducted by patient, procedure, and operator-specific variables. Odds ratios and 95% confidence intervals for the outcome of intubation on first attempt using video laryngoscopy are displayed for the overall study at the top of the figure followed by all subgroups. * Adjusted Device Experience represents the primary outcome for reference. The right justified columns are P-values for interaction terms entered into the logistic regression model to test for effect modification of any of the subgroup variables. There were no patient- or procedure-specific subgroups that benefitted from intubation with video laryngoscopy nor were there any statistically significant interactions detected. Regarding the operator specific variables of previous experience with the assigned intubating device, previous total intubating experience, and previous fellowship training experience, operators less experienced with the assigned device (< 30 previous uses of the device, median) and the intubation procedure (< 50 total intubations, lowest quartile of experience) had a higher odds of intubation on first attempt with video laryngoscopy. However, only previous total intubating experience (< 50 total intubations) modified the effect of video laryngoscopy on intubation on first attempt (p = 0.031).