Low prevalence of methotrexate intolerance in rheumatoid arthritis: a South African study

Methotrexate (MTX) is the first line therapy for rheumatoid arthritis (RA), and despite its widespread use, there is very little information about MTX intolerance in sub-Saharan Africa. The aim of this study was to assess the prevalence of MTX intolerance and other reasons for stopping MTX in RA in South Africa.

A retrospective chart review of all RA patients seen at Inkosi Albert Luthuli Hospital in Durban from 2009 to 2019 was undertaken. We included patients who received MTX for at least three months. All patients received folic acid supplements. Patients who discontinued MTX were categorized as having either MTX related toxicity or other reasons.

A total of 695 patients were identified with a female to male ratio of 7:1. The mean age was 57.9 (± 13.3) years, and median duration of MTX use was 67.0 (39.0-106.0) months. Most of the patients were African Blacks (61.2%), and Indians (32.8%). There were 83 (11.9%) patients who stopped MTX, and it was successfully reintroduced in 25 of them. Thus, 58 (8.3%) patients discontinued therapy, 33 (4.7%) due to intolerance and 25 (3.6%) due to factors other than adverse effects. The commonest causes of MTX intolerance were respiratory, gastrointestinal and haematological. The other reasons for discontinuation included co-morbidities and pregnancy related concerns.

The low prevalence of MTX intolerance in a multiethnic population in this single centre study, confirms the value of MTX as anchor therapy, especially in resource constrained settings. Key Points • We report a low and similar prevalence of methotrexate intolerance in a large population of African Blacks and Indians with RA in sub-Saharan Africa. • Even though there was heterogeneity among other studies, our review indicates that MTX was tolerated better in our patients compared to patients in Europe and the United States of America.