Pancytopenia induced by low‐dose methotrexate. A study of the cases reported to the Finnish Adverse Drug Reaction Register from 1991 to 1999

Abstract

OBJECTIVE: To study cases of low-dose methotrexate-induced pancytopenia with special reference to clinical outcome and factors predisposing to bone marrow suppression. METHODS: Patient files of 14 cases of methotrexate-induced pancytopenia reported to the National Agency for Medicines in Finland from 1991 to 1999 were reviewed. A review of four additional cases was included. RESULTS: Of the 18 patients (median age 72 years), 12 had rheumatoid arthritis, one psoriatic arthritis, five psoriasis without arthritis, and one pemphigus erythematosus. Major co-morbidity was recorded in 12 patients, and 16 patients used significant concomitant drugs. Eight patients had a mildly or moderately elevated serum creatinine concentration. In every patient the occurrence of cytopenia was abrupt. Eight patients (44%) died, and the most frequent cause of death was infection. CONCLUSIONS: Our data show that methotrexate-induced pancytopenia is associated with high mortality especially in cases with significant co-morbidity and concomitant medications.