Practice Pattern of Hepatitis B Testing in Rheumatoid Arthritis Patients: A Cross-National Comparison Between the US and Taiwan

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.