The choice of second-line therapy in steroid-resistant immune thrombocytopenia: role of platelet kinetics in a single-centre long-term study.

Splenectomy is a time-honoured well established approach for patients with steroid-resistant immune thrombocytopenia (ITP). However, due to the more recent availability of therapeutic options alternative to splenectomy, such as rituximab and agonists of the thrombopoietin-receptor, the choice of second-line therapy is challenging. Platelet kinetics has been widely used to predict response to splenectomy. We describe the outcome of 70 chronic ITP patients who performed a platelet kinetic study after failure of front-line corticosteroids and subsequently underwent open splenectomy. After a median follow-up from surgery of 20 years, 62 (88.5%) patients responded to splenectomy and 9 patients (13%) relapsed. Achieving a complete response (CR) significantly predicted a higher probability long-term stable response. The pattern of platelet sequestration was predominantly splenic in 52 patients (74%), predominantly hepatic in 12 patients (17%), and diffuse in 6 (9%). Patients with nonsplenic (diffuse and hepatic) sequestration showed significantly lower overall responses compared to patients with splenic captation (P = 0.002). A nonsplenic sequestration significantly correlated with lower CR rate and, among CR patients, predicted an increased risk of relapse. Also, the probability of stable responses in nonsplenic uptake patients was substantially lower than in patients with splenic uptake (85% vs. 50%, P = 0.0083). Platelet life span and platelet turnover did not correlate with response and relapse rate. Overall, splenic sequestration was able to predict not only a better quality, but also a higher durability of the responses. However, it should be enphasized that the response rate and duration of response even in patients with nonsplenic uptake were similar or even superior to those reported in patients treated with rituximab as first option.