MONITORING OF METHOTREXATE BLOOD TOXICITY DURING THE COVID-19 PANDEMIC FOR PATIENTS WITH RHEUMATOID ARTHRITIS: DATA FROM THE GREATER MANCHESTER CARE RECORD

ABSTRACT

Background/Aims Current British Society for Rheumatology guidance suggests 3- monthly blood monitoring for patients prescribed methotrexate whose disease, drug dosage and blood results are stable, although evidence for this recommendation is limited. Anecdotal reports suggest monitoring may have reduced during the pandemic. The study aims were, in patients with rheumatoid arthritis (RA) prescribed methotrexate, to determine 1) interval length between blood tests during the pandemic, and 2) whether prolonged intervals were associated with abnormal blood test results. Methods Data came from the Greater Manchester Care Record, a database containing electronic health records from both primary and secondary care for people across Greater Manchester. Inclusion criteria were a diagnosis of RA;regular blood monitoring (<=91 days between blood tests) and regular methotrexate prescriptions in the year prior to the pandemic (01/03/2019-01/03/2020). Blood test intervals during the pandemic were determined, a prolonged interval was defined as>91 days. Cytopenia and transaminitis events were identified between March-December 2020 and March-December 2019 (as a comparator). Proportions of events are presented for each time-period and stratified by whether the interval was prolonged. Results 1011 patients met the inclusion criteria, with a median of 5 blood tests (interquartile range (IQR) 3-7) during the pandemic and a median interval of 57 days (IQR 34-84). 612 (61%) patients had at least one prolonged interval, with 241 (23.8%) having multiple. Prolonged intervals had a median length of 112 days (IQR 99-135). 115 (11.4%) people had a prolonged interval but no subsequent blood test before the study end date (median 120 days [IQR 104-150]). The proportion of cytopenia and transaminitis events was low and similar across time-periods and when stratified by interval length (Table 1). Conclusion Nearly two-thirds of patients on stable methotrexate had at least one prolonged interval and 1 in 10 had a prolonged interval with no subsequent blood test. Initial analyses of test results do not indicate increased occurrence of methotrexate blood toxicity in those with prolonged blood test intervals during the pandemic. Further work is required to determine whether those with prolonged intervals represent a group at lower risk where less frequent blood tests would be appropriate.