LAUSR

Our unit currently follows the 2019 British Society of Rheumatology Guidelines in the prescribing and monitoring of bDMARDs which advocates 3-6 monthly monitoring blood tests in patients prescribed a biologic without a concomitant csDMARD. The guideline acknowledges “there is no evidence on the optimal monitoring requirements for patients receiving biologics”. In particular there is lack of evidence on the extent to which routine blood monitoring in such patients results in the discontinuation of the biologic. Given the costs associated with complying with this aspect of the guideline we devised this project to describe at-home biologic prescribing trends at our unit over the previous 5 years and to identify the rate of biologic discontinuation due to dyscrasias. We retrospectively analysed all at-home biologic prescriptions issued at our unit between 2017 and 2021 to describe temporal trends in biologic prescribing habits. We used this data to identify patients that discontinued biological therapies and then performed a detailed retrospective analysis of electronic case records of patients who discontinued an at-home anti-TNF biologic (adalimumab, etanercept, golimumab, and certolizumab) between 01/01/2017 and 31/12/2018 to describe the reasons for discontinuation of anti-TNF biologics. Blood dyscrasia was defined as: white cell count <3.5 × 109/l; neutrophils <1.6 × 109/l; creatinine increase >30% over 12 months and/or calculated GFR <60 ml/min; unexplained eosinophilia >0.5 × 109/l; ALT and/or AST >100 U/l; platelet count <140 × 109/l; unexplained reduction in albumin <30 g/l. Between 2017 and 2021 our unit issued a total of 39,298 prescriptions for at-home biologics. During this timeframe the total number of annual prescriptions at our unit increased by 76.6% (2017: 5240, 2021: 9265) and the number of unique patients prescribed a biological therapy increased by 72.4% (2017: 1018, 2021: 1755). The total number of anti-TNF biologic prescriptions increased by 49.8%, and the number of adalimumab prescriptions increased by 89.8%. Between 1/1/2017 and 31/12/2018 295 patients discontinued an anti-TNF biologic. Reasons for discontinuation included: drug inefficacy: n = 156 (52.9%), treatment de-escalation: n = 15 (5.1%), adverse event (e.g. infection, side effect, intolerance): n = 36 (12.2%), blood dyscrasia: n = 4 (1.4%), patient lost to follow up: n = 43 (14.6%), pregnancy: n = 8 (2.7%), other (e.g. malignancy, heart failure, interstitial lung disease): n = 33 (11.2%). Our data suggests that prescription of at-home biological therapies has increased significantly between 2017-2021. Amongst patients taking anti-TNF therapies the number of patients discontinuing therapy due to blood dyscrasia was very low. In view of the increasing number of biologic prescriptions and the associated costs of 3-6 monthly blood monitoring, further data to determine the optimal monitoring requirements for patients on biological therapies is needed. Disclosure M.D.J. Gibson: None. J. Wells: None. S. Subesinghe: None.