1173. Increased risk of dementia in patients after Scrub typhus: a nationwide, population-based study in Korea

Abstract

Abstract Background Scrub typhus causes systemic vasculitis and can lead to complications ranging from pneumonia and acute renal injury to meningitis or encephalitis. In South Korea, it occurs not only in rural areas but also in urban areas, and especially high in older people. We hypothesized that patients with scrub typhus are predisposed to increased risks for developing dementia. Methods We performed a population-based cohort study, in which persons aged between 60∼89 years, used the Health Insurance Review and Assessment database of South Korea between 2009 and 2018. The case definition of scrub typhus was based on the ICD-10 diagnostic code and prescription of doxycycline more than three days. Dementia was defined as patients with the code in expending benefit coverage or patients with the ICD-10 codes, examination codes and drug codes. The control group was selected as stratifying by age and gender at a ratio of 1:5 to the number of the case group in study population. Results During the observational periods, Of 76,073 patients had diagnosed with scrub typhus, 5,026 excluded due to diagnosed with scrub typhus during window period, with dementia or died before index date, 71,047 patients were included as case group. 355,235 patients were included as controls. During a mean follow-up of 5.6±2.9 years, 14,089 (19.8%) patients with previous scrub typhus and 61,807 (15.2%) controls had been developed dementia. Scrub typhus was significantly associated with dementia (adjusted hazard ratio [aHR], 1.12; 95% confidential interval [CI], 1.10-1.15, P< 0.001). Of dementia classification, the risk of Alzheimer dementia was significantly higher in the case group (17.8% vs 15.2%; aHR, 1.15; 95%CI, 1.13-1.18, p< 0.001), however, there was no significant difference in the risk of vascular dementia (2.1% vs 2.2%; aHR, 0.98; 95%CI, 0.83-1.16, p=0.82). Cumulative incidence of dementia during the follow-up period by the history of scrub typhus It shows in both groups dementia incidence increased over time and the case group had higher incident dementia compared with control group. Conclusion History of scrub typhus infection in elderly was associated with increased risk for dementia, especially Alzheimer’s dementia. Our results suggest that prevent measures of dementia could be improved by preventing and treating scrub typhus. Disclosures All Authors: No reported disclosures.