Imputing missing quality of life data as covariate in survival analysis of the International Breast Cancer Study Group Trials VI and VII

Marion Procter, Charles Robertson

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Quality of life (QoL) was an important endpoint in the adjuvant breast cancer trials International Breast Cancer Study Group (IBCSG) Trial VI and VII. Here, QoL was considered as a time-dependent effect. The hypothesis explored is that poorer QoL throughout the trial is associated with poorer disease-free survival (DFS) and vice-versa. Potential bias in the parameter estimates is an important concern associated with missing observations. Standard simple and multiple imputation methods were applied to missing QoL assessments before analysis in a time-dependent Cox model. There was no evidence that the patient's QoL is related to the patient's DFS.
Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalCommunications in Statistics - Simulation and Computation
Early online date30 Oct 2017
Publication statusPublished - 15 Dec 2017


  • informative missing data
  • multiple imputation
  • potential bias
  • qualify of life
  • simple imputation
  • time-dependent Cox model

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