PANCYTOPENIA ASSOCIATED WITH LOW-DOSE METHOTREXATE THERAPY - A REGIONAL SURVEY

Objective. To determine which risk factors are associated with serious pancytopenia associated with low dose methotrexate (MTX) therapy. Met hods. All Ottawa area rheumatologists, hematologists and dermatologist s were surveyed to obtain cases of pancytopenia associated with low do se MTX therapy between 1981 and 1991. Pancytopenia was defined as whit e blood cells < 3.5 x 10(9)/l and platelets < 140 x 10(9)/l and hemogl obin < 100 g/l. A case control method was used to evaluate risk factor s. Results. Fifteen cases of pancytopenia were identified from returne d questionnaires (93% response rate) and from reviewing the medical re cords of 2 major teaching hospitals. All patients were hospitalized, h ad MTX therapy discontinued and were treated: 12 patients received tra nsfusions, 8 leukovorin therapy, and 4 folic acid. Two patients died, only 1 directly due to MTX therapy. Identified risk factors were (1) e levated BUN or creatinine levels, (2) increasing mean corpuscular volu me values, (3) increased age and (4) concomitant trimethoprim-sulfamet hoxazole therapy. Conclusions. Pancytopenia associated with low dose M TX therapy is a life threatening adverse effect often associated with known risk factors. A change in monitoring guidelines and patient educ ation are suggested as means of risk reduction.