Background MTX has gained wide acceptance of the most useful disease-modifying anti-rheumatic drugs. But, MTX cause serious toxicities including hepatic abnormalities, pneumonitis, and myelosuppression.
Objectives To assess the associated risk factors of methotrexate (MTX)-induced cytopenia in rheumatoid arthritis (RA).
Methods We followed 420 patients started on MTX for RA. We evaluated the frequency and clinical significance of patients with cytopenia related to MTX therapy.
Results The prevalence of patients remaining in the follow-up in the MTX treatment was 21% at 60 months. A total of 10 patients with cytopenia related to MTX therapy were identified among them. The prevalence of cytopenia, including leukopenia (n = 6), thrombocytopenia (n = 3) and pancytopenia (n = 1), estimated to be 2.4% in MTX treated RA patients.
Patients with cytopenia received 2.5‑8 mg/w over a mean duration of 60.0 months (10‑119 months). Nine of 10 patients received NSAIDs with MTX therapy. The presence of renal abnormality (Cr >1.2 mg/d) was in 3 cases, age over 70 years old in 4 patients, body weight under 50 kg in 8 patients, mean corpuscular volume (MCV) over 100 fl in 2 patients. High MCV value (over 94 fl) was in 7 patients, 6 of whom had some symptoms including fever (n = 3) and oral mucosa/lip abnormalities (n = 3). Low MCV value (under 84 fl) was in 3 patients, who had no symptoms but arthralgia and no renal abnormality. And they were younger and received MTX in shorter period than high MCV group.
Conclusion In patients with high MCV (over 94 fl), most haematological toxicities seen during the course of MTX therapy can be predictable. But, some patients may develop unpredictable haematological reaction.
American College of Rheumatology ad hoc Committee on Clinical Guidelines. Guidelines for monitoring drug therapy in rheumatoid arthritis. Arthritis Rheum 1996;39:723–31
Gutierrez-Urena S, Molina Cesar JF, Garcia O. Pancytopenia secondary to methotrexate therapy in rheumatoid arthritis. Arthritis Rheum. 1996;39:272–6
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