Healthcare Utilization and Cost of Herpes Zoster Infection in Patients With Rheumatoid Arthritis: A Retrospective Cohort Study.

OBJECTIVE: Patients with rheumatoid arthritis (RA) have an increased risk of developing herpes zoster (HZ) compared to the general population. We aimed to measure healthcare utilization (HCU) and related costs of HZ among patients with RA, from the public payer's perspective. METHODS: Adult patients with RA diagnosed with HZ between 2008 and 2020 were matched by sex, age, and date of HZ infection to (1) patients with RA without HZ, (2) the non-RA population with HZ, and (3) the non-RA population without HZ. Unadjusted gamma distribution models and generalized estimating equations were used to compare HCU costs and the number of clinical events (CEs), including hospital admissions and emergency department and physician visits, in patients with RA with HZ to each matched cohort. RESULTS: We identified 15,573 patients with RA diagnosed with HZ and a similar number for each of the 3 matched cohorts. From year 1 to year 10, mean total cost ranged from CAD $13,507 to CAD $17,120 for the RA with HZ cohort compared to CAD $12,651 to CAD $14,534 in the RA without HZ cohort. Physician billing and inpatient hospital costs were the largest drivers of increased costs for all cohorts. Compared to patients with RA with HZ, each matched cohort experienced a significantly lower mean number of total CEs, with the highest difference in total CEs 1 year following an HZ infection. CONCLUSION: HCU and related costs were higher in patients with RA with HZ compared to patients with RA without HZ and non-RA populations with and without HZ. Treatment strategies that minimize the risk of HZ and encourage patients to keep up to date with vaccinations should be considered.