Survival of Captive Chimpanzees: Impact of Location and Transfers

To inform the retirement of NIH-owned chimpanzees, we analyzed the outcomes of 764 NIH-owned chimpanzees that were located at various points in time in at least one of 4 specific locations. All chimpanzees considered were alive and at least 10 years of age on January 1, 2005; transfers to a federal sanctuary began a few months later. During a median follow-up of just over 7 years, there were 314 deaths. In a Cox proportional hazards model that accounted for age, sex, and location (which was treated as a time-dependent covariate), age and sex were strong predictors of mortality, but location was only marginally predictive. Among 273 chimpanzees who were transferred to the federal sanctuary, w