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Accounting for bias due to a non-ignorable tracing mechanism in a retrospective breast cancer cohort study.

Research output: Contribution to journalJournal article


<mark>Journal publication date</mark>20/02/2011
<mark>Journal</mark>Statistics in Medicine
Number of pages11
<mark>Original language</mark>English


We consider the analysis of competing risks in a retrospective breast cancer cohort study where tracing of patients is dependent on survival to a pre-specified truncation time. We demonstrate that if ignored the observed cause-specific hazards will become distorted before the truncation time. Two approaches to account for the tracing bias are considered. Firstly, a likelihood based method using piecewise constant transition intensities under a Markov assumption. Secondly, a pseudo-likelihood method using inverse probability of tracing weights. For the breast cancer example, both methods improve the precision of estimates compared to a conventional approach based on excluding patients.