P202 Monitoring of immunoglobulin levels in RA patients on anti CD20, rituximab

Abstract

Abstract Background Rituximab is an anti-CD-20 used in resistant RA. It functions by reducing the efficacy of B cells which participate in this pro-inflammatory process. The BSR recommend immunoglobulin monitoring when using rituximab to aid rapid detection of hypogammaglobinaemia and address its potential complications which have been suggested by a recent large study in 2018 in the UK. Our objectives included: Are we measuring immunoglobulin (Ig) levels prior to rituximab infusions in all RA patients? Are we measuring Ig levels ‘4-6 months post infusions’ as per BSR guidelines? Is the cumulative dose of rituximab associated with hypogammaglobinaemia? Methods We collected data from departmental records for all the RA patients who were initiated on rituximab between 30/1/15 and 30/1/19. We recorded their basic demographics, pre-infusion immunoglobulin levels and subsequent levels with repeated infusions. All data was anonymised, but some patients had to be excluded from the final analysis due to missing immunoglobulin levels. Results 42 patients were identified via the methodology. 88% of the 42 had Ig’s checked before starting rituximab. Only 38% of 37 patients included in this subsequent analysis had Ig’s checked within the recommended 6 months after their initial rituximab infusion. We also observed a notable average percentage drop in IgG levels after receiving approximately 6g of rituximab therapy, with 2 new patients developing new hypogammaglobinamia after 8g-10g of rituximab. After 10g of rituximab we noted an average percentage drop in rituximab of 26.8%. However, no statistical correlation between hypogammaglobinaemia and infection rates was found. Conclusion Although no correlation between hypogammaglobinaemia and infection rates were found, this study used small numbers from a single centre only. To improve UHW’s monitoring of Ig’s we introduced a performer which aims to help recording of pre and post IgG levels and recording of infections experienced between infusions. We hope this will increase identification of newly developed hypogammaglobinaemia and increase awareness of infection rates, ultimately leading to an improvement in patient care. Disclosures C. Rice None. D. Ghandi-Das None. A. Negi None.