Methotrexate-induced pancytopenia: a case series of 46 patients.

AIM: Methotrexate (MTX) has the potential to cause serious adverse reactions and even mortality. We analyzed the predisposing factors and outcome in patients with MTX-induced pancytopenia admitted into our unit from 1996 to 2015.

METHODS: Patients were identified by departmental database search. Pancytopenia was defined as white blood cell count (WBC) < 3500 cells/mm3 , hemoglobin (Hb) < 11 g/dL and platelet count < 150 000 cells/mm3 . Severe pancytopenia was defined as WBC < 2000 cells/mm3 , Hb < 10 g/dL and platelet count < 50 000 cells/mm3 .

RESULTS: Forty-six patients were included in the study (female = 35). Twenty-four had been under the care of either primary care physicians or orthopedic surgeons and presented to us with pancytopenia. Sixteen patients had severe pancytopenia. Disease distribution was as follows: rheumatoid arthritis 33, psoriasis eight, systemic sclerosis two and others three. The median dose of MTX was 10 mg/week and median duration of treatment was 11 months. The median cumulative dose was 750 mg. Symptoms at presentation included: oral mucositis (n = 37); fever (n = 24); diarrhea (n = 12), bleeding gums (n = 5) and purpura (n = 3). The potential risk factors were: hypoalbuminemia (n = 23), renal insufficiency (n = 14), dosing errors (n = 13) and non-supplementation of folates (n = 7). Thirteen patients died. WBC at admission was found to determine survival (P < 0.05).

CONCLUSION: In patients on MTX, oral mucositis and fever can herald pancytopenia. MTX-induced pancytopenia is associated with high mortality. WBC at admission is the most important prognostic factor. There is need for increased awareness among physicians to minimize prescribing errors. A national guideline on monitoring of patients on MTX is desirable.