The draft ICH E9 (R1) addendum by the International Conference on Harmonisation working group opens for the use of a principal stratum in the analysis of study data for regulatory purpose, if a relevant estimand can be justified. Inspired by the so-called complier average causal effect and work within this framework, I will propose a new estimator – Extrapolation based on propensity to comply – that estimates the treatment effect of an active treatment A relative to a comparator B (active or placebo), in the principal stratum of patients who would comply, if they were treated with treatment A. Sensitivity of the approach to the number of covariates and their ability to predict principal stratum membership will be shown based on data from a placebo-controlled study of brexpiprazole in schizophrenia. The performance of the estimator is compared with another estimator that is also based on principal stratification. A simulation study supports that the proposed estimator has a negligible bias even with a small sample size, except when the covariate predicting compliance is very weak. Not surprisingly, precision of the estimate increases substantially with stronger predictors of compliance.
You can find CSS next to the Botanical Garden, 5 minutes from Nørreport station.
Meeting room 5.2.46 is the library of the Biostatistics section, located in building 5, 2nd floor, room 46. See the map below for directions inside CSS.