Background: Biologic agents were initially introduced as treatment for rheumatoid arthritis (RA) but have since been used for other medical conditions. As new biologics become increasingly widespread in treatment regimens, it is important to understand their safety and utilization in the post-marketing context.

Purpose: The aim of this study was to investigate long-term prescribing patterns and the safety of biologics in real clinical settings in Hong Kong.

Methods: This was a population-based drug utilization study in Hong Kong using a territory-wide electronic medical database Clinical Data Analysis and Reporting System (CDARS). Patients who received biologic treatments from 2001 to 2015 were identified and their corresponding demographic and clinical details retrieved from CDARS. The annual prevalence of biologic prescriptions, the long-term retention rates and incidence rates of infections associated with biologic treatments were evaluated.

Results: A total of 30,298 patients (male: 44%) prescribed biologic treatments were identified from CDARS from 2001 to 2015. The annual prevalence of biologic prescriptions increased from 0.1 to 16.1 per 100 persons for both sexes. Infliximab had the highest first-year retention rate of 95.6% among all biologics and continuously attained the highest retention rate from second to fifth year. The overall incidence rate of serious infections was less than five per 100 person-years. Specifically, the incidence rates of tuberculosis, upper and lower respiratory infections and herpes zoster were 0.52, 3.24, 4.99 and 1.01 per 100 person-years, respectively.

Conclusion: This population-based study revealed an increasing prevalence of biologic prescribing. Results from the study described the long-term retention rates and incidence rates of serious infections of biologic treatments for all indications, and confirmed the safety of biologic treatments. Since this study provides an overview of all biologic utilization, further studies on cost effectiveness, safety and compliance of treatment in different patient groups are still warranted.