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Missing information because of death in time-to-event analyses of clinical and epidemiological studies

Duration: 36 months

Principal Investigator: Prof. Dr. Martin Schumacher (IMBI)

Prof. Dr. Martin Schumacher (IMBI)
Dipl.-Math. Nadine Binder (IMBI)
Dr. Anette Blümle (German Cochrane Centre)
Edith Motschall (IMBI)


In most clinical and epidemiological studies information on disease status is usually collected at regular follow-up times. Often, this information can only be retrieved in those individuals, who are alive at follow-up and will be missing in those who died before follow-up. The arising complications are of particular relevance in long-term studies and/or when studying elderly populations. There is some indication in the biomedical literature that clinical and epidemiological studies have excluded individuals with missing information because of death and restricted the analysis to the surviving ones. These naive analyses can lead to serious bias in incidence estimates that is then transferred to bias in estimates of hazard ratios corresponding to potential risk or prognostic factors. Within the project we will investigate the prevalence of this bias in highly-cited medical and epidemiological journals. We will further elaborate on a formula for the resulting bias in order to estimate its direction and magnitude based on individual study characteristics. We will investigate several statistical approaches based on multi-state models and related regression methodology in order to allow for an adequate and unbiased analysis. This should lead to the development of a comprehensive analysis strategy for studies where missing information because of death constitutes a problem. This strategy will then be used for the reanalysis of some existing studies. Finally, we will work out recommendations for the design of studies in order to avoid this bias or to keep it in negligible magnitude.