(C-032) Lyme Disease Reinfections: An analysis of US Health Insurance Claims Data

Background: Lyme disease (LD) is the most common tick-borne infection in the United States (US) and there is no human vaccine available. Based on prior studies, LD reinfections occur in approximately 1-3% of people annually; however, there is a paucity of data on reinfection rates and populations at higher risk. With the increasing incidence and geographic spread of LD, a better understanding of reinfections is important.

Objectives: To estimate the rate of reinfections among people with Lyme Disease in the US.

Methods: Patients with newly diagnosed LD were identified in the HealthVerity closed claims database from January 1, 2018 through December 31, 2023. LD was defined as the first recorded medical claim with 1+ ICD-10-CM diagnosis code A69.2x and a prescription claim for an antibiotic drug of >= 7 days duration filled within 30 days before or after the LD medical claim. Patients were required to have no prior LD diagnosis from the start of all available data (October 1, 2015) through the index date (date of first LD diagnosis). Patients were followed from the date of the first LD diagnosis until the end of the study period (June 30, 2024) or until they were disenrolled. LD reinfections were events meeting the LD case definition that occurred >12 months after the previous LD infection. Reinfection rates per 1,000 person-years (PYs) were calculated among individuals with incident LD.

Results: Among 220,331 incident LD cases identified from 2018-2023, we identified 7,744 (3.5%) who had at least one reinfection during follow-up through up to 5 years after the first LD diagnosis, for a reinfection rate of 16.5 per 1,000 PYs among persons with previous LD. The mean time between first infection and reinfection was 715 days (2 years) and the mean number of reinfections was 1 (range 1-5). The highest reinfection rate was in ages 40-49 years (21.7 per 1,000 PYs) and the lowest was in ages 5-9 years (6.2 per 1,000 PYs).

Conclusions: In a large database of patients in the US the LD reinfection rate was 16.5 per 1,000 PYs and was higher in adults than children. These may be overestimates of the true incidence because reinfections captured in this analysis could be cases of post-treatment Lyme disease syndrome and/or indicative of ongoing care for a first infection. In additional analyses, we will apply a washout period after each LD infection to exclude cases with ongoing medical encounters for LD to attempt to address this issue. Additional sensitivity analyses will also be conducted. These data can inform the understanding of the burden of LD reinfection and LD vaccine development.