E018 Prophylactic co-trimoxazole prescribing practice in patients who received rituximab therapy: comparison across indications and specialties
Authors: Tio Sherdya Worthy , Morrow Juliette , Cowley Sharon , Clarkson Michael , Murphy Grainne 
Published: April 2024

Abstract

Background/Aims
Rituximab is a chimeric anti-CD20 monoclonal antibody targeting B-cells used as part of treatment algorithms for malignancy and autoimmune diseases. As is the case of other immunosuppressive agents, rituximab increases the risk of infections. Primary prophylaxis with co-trimoxazole may be considered in high-risk cohort of patients to prevent opportunistic infection, particuarly Pneumocystis jerovecii pneumonia (PJP).
To investigate the prescribing practice for prophylactic co-trimoxazole in patients who received rituximab infusion in a large tertiary referral centre. To compare practices between rheumatology and nephrology department. To compare the incidence of hospitalisation for infection (particularly PJP) between those prescribed prophylactic co-trimoxazole and those who did not.

Methods
This was a single centre retrospective observational study over a 3 year period assessing prophylactic co-trimoxazole prescribing practice in 185 patients attending rheumatology or renal services in Cork University Hospital (CUH) and receiving rituximab. Co-trimoxazole prophylactic treatment was defined as prophylaxis dose of co-trimoxazole (either 480mg daily or 960mg three times per week) received during rituximab treatment and at least 6 months post completion of treatment.

Results
185 patients’ medical charts were reviewed. Only 28 patients received prophylaxis with co-trimoxazole. The majority of patients (n = 24, 85%) who received prophylaxis with co-trimoxazole had an underlying diagnosis of small vessel vasculitis (SVV). Co-trimoxazole was more commonly prescribed by nephrologists (n = 17, 71% primarily for SVV) as compared to rheumatologist (n = 7, 29% primarily for SVV).
156 patients were not prescribed prophylactic co-trimoxazole. The primary indication for rituximab in these patients was inflammatory arthropathy (IA) (n = 72,46%), SVV (n = 26, 16%), systemic lupus erythematosus (n = 19, 12%), with the remainder accounted for by scleroderma, undifferentiated connective tissue disease, membranous nephropathy (MN), myositis, focal segmental glomerulosclerosis and amyloid renal disease.
No patient was admitted over the course of the study period with PJP.
59 patients required hospital admissions due to other infections, most commonly patients with SVV. The most common infections were respiratory tract and urinary tract infections. Overall infections requiring hospitalization were more common in the group receiving prophylaxis, perhaps highlighting the vulnerable nature and greater prednisolone prescribing in the SVV cohort. No difference was seen between groups in the prevalence of UTIs.

Conclusion
In this cohort co-trimoxazole prophylaxis was more commonly prescribed for patient with small vessel vasculitis and differences in prescribing patterns were seen between nephrologists and rheumatologists. With greater awareness of the heightened risk of PJP in patents receiving rituximab consideration should be given to use of antibiotic prophylaxis for other indications.

Disclosure
S. Tio: None. J. Morrow: None. S. Cowley: None. M. Clarkson: None. G. Murphy: None.