THROMBOCYTOPENIA IN PATIENTS WITH RHEUMATOID-ARTHRITIS ON LONG-TERM TREATMENT WITH LOW-DOSE METHOTREXATE

We reviewed the records of 315 patients with rheumatoid arthritis (RA) treated with low-dose methotrexate (MTX) and evaluated the conditions contributing to thrombocytopenia, Thirteen out of 315 patients with R A presented with low platelet counts (less than or equal to 100.000/mm (3)). The age of these patients (51 +/- 12.6 years) did not correlate with thrombocytopenia (r = 0.211, p > 0.05), Thrombocytopenia resulted from coadministration of MTX and NSAID or multiple drug interactions, We observed a significant (r = 0.48, p < 0.05) increase of discontinu ation of NSAID's but not of MTX therapy (r = 0.42, p > 0.05) with a mo unting weekly dosage of MTX (12.5 +/- 5 mg orally), There was a signif icant correlation between this weekly dosage of MTX coadministered on the same day with NSAID and thrombocytopenia (r = 0.6, p < 0.05), In m ost cases (9/13) MTX was not or just temporarily withdrawn, Three of t he remaining patients had multiple drug interactions, Reintroduction o f low dose MTX treatment in patients having had thrombocytopenia could be performed safely, if thrombocytopenia occurred as a result of conc omitant application of MTX and NSAID and no other multiple drug intera ctions, Preferably, MTX and NSAID should be given to these risk patien ts on separate days or intervals considering half time clearance of NS AIDs, This procedure has prevented the reoccurrence of thrombocytopeni a and controlled further drug interactions of NSAIDs and MTX in our pa tients.