A Terminal Decline Model for Quality of Life and Survival in Palliative Care Studies

• Activity Number: 510
• Type: Contributed
• Date/Time: Wednesday, August 1, 2012 : 10:30 AM to 12:20 PM
• Sponsor: Biometrics Section
• Author(s): Zhigang Li*+ and Tor Tosteson and Marie Bakitas
• Companies: Dartmouth Medical School and Dartmouth Medical School and Dartmouth Medical School
• Keywords: end of life ; joint modeling ; palliative care ; quality of life ; survival ; terminal decline

Abstract

Palliative care is a specialized area of healthcare that focuses on helping to relieve and prevent the suffering of patients facing life-threatening illness. It is known that quality of life (QOL) of patients with advanced cancer decreases as death approaches, this association is generally not taken into account when inferences of the effect of an intervention on quality of life or survival times are made in previous clinical trials. We develop a new joint modeling approach: terminal decline model to study the trajectory of repeated measurements for palliative care studies having cancer patients. This approach takes that association into account by modeling the QOL retrospectively from death. For those patients whose death times are censored, marginal likelihood is used to incorporate them into the analysis. Our approach has two submodels: a piecewise (two pieces) random intercept model with serially correlation and measurement error for the retrospective trajectory of QOL and a piecewise exponential model for the survival distribution. MLE of the parameters are obtained by maximizing the closed-form expression of log-likelihood function.