EVALUATION OF THE EFFECTIVENESS AND SAFETY OF SWITCHING FROM INTRAVENOUS TO SUBCUTANEOUS TOCILIZUMAB

ABSTRACT

Background and importance In the context of the COVID-19 pandemic, one of the strategies implemented to minimise patient visits to health centres was switching the administration of tocilizumab (TCZ) from intravenous (IV) to subcutaneous (SC). Aim and objectives To evaluate the effectiveness and safety of switching from IV to SC TCZ. Material and methods Retrospective observational study conducted in a tertiary hospital including patients receiving active treatment of IV TCZ during the period March-April 2020. Data were collected on the following variables age, sex, pathology, switching to SC TCZ, switching back to IV administration, physician assessment or patient self-assessment, as well as adverse reactions. The follow-up period was 1 year. Results A total of 45 patients were included, with a median age of 54 (40-62) years. Women represented 85%. Patients included were diagnosed with rheumatoid arthritis (49%), juvenile idiopathic arthritis (18%), Graves disease (13%), lupus (2%), spondylarthritis (2%) and other diagnoses (16%). The prescribing physicians were rheumatologists (62%), internists (24%) and paediatricians (13%). Of 45 patients, 71% (n=32) switched to SC TCZ during the study period. 86% of rheumatology, 83% of paediatrics and 27% of internal medicine patients changed to SC TCZ. Aggravation after switching to SC TCZ was reported in 7/ 32 (22%) cases (5 with rheumatoid arthritis and 2 with juvenile idiopathic arthritis). All of these switched back to IV administration, plus 4 additional patients for undetermined reasons. Of those who switched back to IV administration due to clinical worsening, 4 reported improvement afterwards. Regarding safety, only 2 patients suffered adverse reactions after switching to SC (injection site reaction, palpitations, tremor and oedema). Neither of them switched back to IV administration. Conclusion and relevance One-fifth of the patients reported loss of effectiveness when changing from IV to SC form, and one-third switched back to IV administration. Regarding safety, the toxicity profile of both forms was similar to other studies. The effectiveness results observed are in contrast with the MUSASHI study, which did not report loss of efficacy after switching from IV to SC. However, effectiveness was not measured using the internationally validated ordinary objective scales (DAS28, CDAI), but physician subjective assessments or patient self-assessments, which represents a significative limitation for our study.