Health characteristics and aspirin use in participants at the baseline of the aspirin in reducing events in the elderly – eXTension (ASPREE-XT) observational study

Background: Aspirin as a primary preventative in healthy older adults did not prolong disability-free survival in the ASPREE randomized trial. Observational studies following randomized trials allow assessment of benefits and harms which may not appear during the trial. We describe health characteristics, physical function, and aspirin use in the ASPREE-eXTension (ASPREE-XT) observational study cohort. Methods: Descriptive statistics compared health characteristics of those consented to ASPREE-XT at their first post-trial baseline (XT01) to corresponding ASPREE baseline values, and to those not consented. Likelihood of an indication for aspirin was assessed in participants reporting aspirin use at XT01. Results: 16,317 (93%) of the remaining and eligible 17,546 ASPREE participants were consented into ASPREE-XT; 14,894 completed XT01. Mean participant age had increased from 74.9 to 80.6 years. Overall health and physical function declined from the original ASPREE baseline; more participants were living alone, there was higher prevalence of chronic kidney disease, diabetes, and frailty, grip strength was lower and gait speed slower. Those not consented into ASPREE-XT were slightly older, and had lower cognitive scores and higher prevalence of age-related conditions than those who continued. 1015/11,717 (8.7%) participants without an apparent indication for aspirin reported using aspirin at XT01. Conclusions: The ASPREE-XT cohort was slightly less healthy at the XT01 visit than at ASPREE trial initiation, and rates of aspirin use without indication were similar to ASPREE baseline. Participants will be followed long-term to investigate aspirin's potential legacy towards dementia and cancer prevention and explore determinants of healthy aging.