Health Care Utilization and Cost of Herpes Zoster Infection in Patients with Rheumatoid Arthritis, a Retrospective Cohort Study.

Objective: Rheumatoid arthritis (RA) patients have an increased risk of developing herpes zoster (HZ) compared to the general population. We aimed to measure health care utilization (HCU) and related costs of HZ from the public payer's perspective among RA patients.

Methods: Adult RA patients diagnosed with HZ between 2008 and 2020 were matched (sex, age, and HZ date) to: 1) RA patients without HZ, 2) non-RA population with HZ, and 3) non-RA population without HZ. Unadjusted gamma distribution models and generalized estimating equations (GEEs) were used to compare HCU costs and number of clinical events (CEs), including hospital admissions, emergency department and physician visits, in RA with HZ to each matched cohort.

Results: We identified 15,573 RA patients diagnosed with HZ and a similar number for each of the three matched cohorts. Mean total cost ranged from 13,507 CAD at year 1 to 17,120 CAD at year 10 for the RA with HZ cohort compared to 12,651 to 14,534 CAD in the RA without HZ cohort. Physician billing and inpatient hospital costs were the largest drivers for all cohorts. Compared to RA patients with HZ, each matched cohort experienced a significantly lower mean number of total CEs, with the highest difference in total CEs one year following a HZ infection.

Conclusion: HCU and related costs were higher in RA patients with HZ compared to RA patients without HZ and non-RA populations with and without HZ. Treatment strategies that minimize the risk of HZ and updating patients' vaccinations should be considered.