Objective: The hepatitis B virus (HBV) testing rates and patterns in rheumatoid arthritis (RA) patients starting disease-modifying antirheumatic drugs (DMARDs) have not been well studied. We describe and compare the practice patterns of HBV testing among RA patients in the US and Taiwan. Methods: We conducted a retrospective cohort study, including RA patients starting a first DMARD in the US or Taiwan. The first date patients newly received any DMARD was defined as the index date, and the 1-year period before the index date was the baseline period. HBV testing was defined as any of the following tests 1 year before or after the index date: hepatitis B surface antigen, hepatitis B surface antibody, hepatitis B core antibody, hepatitis B envelope antigen, hepatitis B envelope antibody, or HBV DNA. We calculated the HBV testing rate by year and used Poisson regression to calculate the testing rate ratio. Results: We identified 14,568 RA patients in the US and 46,265 in Taiwan. The overall testing rate was 20.3% in the US and 24.5% in Taiwan, and gradually increased over the study period from 13.1–23.0% in the US and 16.8–30.0% in Taiwan. More than one type of HBV test was used in 43.4% of patients in the US and 16.3% of patients in Taiwan receiving tests. Results of Poisson regression found Taiwan had a 17% higher testing rate over the US during the followup period (crude rate ratio 1.17 [95% confidence interval 1.12–1.22]). Conclusion: We found small differences in the HBV testing rates across the US and Taiwan. Although the rate gradually increased in the past decade, it remained low in both countries.
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