Abstract: Objective The long-term effects of blood donation on health, especially concerning chronic diseases with delayed onset, are not well-studied. The Objective of this study was to investigate the health impacts of blood donation among elderly Chinese donors versus non-donors over an extensive follow-up period. Methods In January 2012, a cohort of adults with matched demographics (birth year, sex, residence) was selected from electronic health records in Shaanxi, China, including equal numbers of blood donors and non-donors. The cohort was followed up until December 31, 2018. Cox regression was used to calculate hazard ratios (HRs) for chronic disease hospitalizations. Multimorbidity network analysis was employed to assess hospitalization patterns. Results A total of 175 715 blood donors and an equivalent number of non-donors contributed to 1 246 130 person-years of follow-up, with a mean age of 50.0±4.4 years. Participants over 45-year-old with more than four and five donations had lower cancer hospitalization rates (adjusted HR 0.894 and 0.872, P<0.001). Those over 50-yaer-old showed lower cancer (adjusted HR 0.783 and 0.748, P<0.001) and respiratory disease rates (adjusted HR 0.883 and 0.845, P<0.001). Donors over 55-yaer-old with more than four and five donations had reduced disease risks (adjusted HR 0.915 and 0.890, P<0.001). Multimorbidity networks showed non-donors had 1.77 times more complex networks than male donors and 2.03 times more complex than female donors. Conclusion Blood donation may lead to better health outcomes in the elderly by reducing hospitalization risks for chronic diseases, suggesting potential health benefits of blood donation with age.

Key words: Blood donation, Health effects, Ageing population, Hospitalisation risk, Multi-morbidity, Electronic health records