In this article we address whether studies of care rendered to patients
prior to their death (“studies of decedents”) produce an accurate
portrait of care provided to patients who are dying. Studies of decedents
typically analyze the care provided to patients over a defined interval antecedent
to death. Studies of dying patients analyze care provided to patients subsequent
to the time that their terminal status is perceived. We address whether 2
fundamental differences between studies of decedents and studies of the dying—the
ways that subjects are identified and the time periods that are examined—lead
to differences in interpretation of study results. Using examples from population-based
cohorts of individuals with cancer, we show that both the differences in subject
selection and time period introduce very substantial biases into studies of
decedents. We conclude that studying care received prior to death can lead
to invalid conclusions about the quality or type of care provided to dying
patients.