Platelet production rate predicts the response to prednisone therapy in patients with idiopathic thrombocytopenic purpura.
The predictive value of clinical and platelet kinetic parameters for treatment outcome in idiopathic thrombocytopenic purpura (ITP) was investigated in 75 patients with platelets<or=20x10(9)/L. The platelet kinetic studies showed that the platelet production rate (PPR) was decreased (<100x10(9)/day), normal, or increased (>355x10(9)/day) in 33%, 48%, and 19% of patients, respectively. All patients started with prednisone at diagnosis (1 mg/kg/day). Initial complete and partial response (CR/PR) rate was 84% and a durable CR/PR (>or=6 months without treatment) was attained in 44% of the patients. Durable CR/PR was noticed in 64% of the patients with decreased PPR during a median follow-up time without treatment of 81 (range 18-92) months, compared to 34% of the patients with normal or increased PPR during a median follow-up time without treatment of 141 (range 10-284) months (p=0.03). Splenectomy was performed in 32% of patients with decreased PPR and in 62% of patients with normal or increased PPR (p=0.03). In conclusion, ITP patients with suppressed PPR have a significant higher durable CR/PR rate to prednisone therapy and are less frequently exposed to splenectomy than those with a normal or increased PPR.