Multiple imputation for time to event data under Kaplan-Meier, Cox or piecewise-exponential frameworks – SAS macros

Multiple imputation (MI) and analysis of imputed time-to-event data is implemented in a collection of SAS macros based on the methodology described in the following publications:

[1] Lipkovich I, Ratitch B, O’Kelly M (2016) Sensitivity to censored-at-random assumption in the analysis of time-to-event endpoints. Pharmaceutical Statistics 15(3):216-229

[2] Moscovici JL, Ratitch B (2017) Combining Survival Analysis Results after Multiple Imputation of Censored Event Times. PharmaSUG-2017 (available on-line

Briefly, the methods estimate multiple imputations via draws from the Bayesian posterior distribution of parameters of a model (piecewise exponential); or via bootstrapped versions of the input data with a standard inverse method translating estimated probability into time to event (Cox and Kaplan-Meier). Hazards can be subjected to increase/decrease via user-specified amount delta; reference-based imputed survival can be implemented by estimating the imputation model based on a user-specified subset of observed subjects (piecewise exponential and Kaplan-Meier); or by user specification of the treatment group parameter to be used when calculating the imputed time to event (Cox).

The macros can be downloaded here: Package_Release_V3 final.

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