Autologous 111In-labelled platelet sequestration studies in patients with primary immune thrombocytopenia (ITP) prior to splenectomy: a report from the United Kingdom ITP Registry

P>While splenectomy is an effective therapy for primary immune thrombocytopenia (ITP), possible complications and observed non-complete response (CR) in one-third of patients demonstrate the need for further research into potential pre-surgical predictors of outcomes. Past investigations into platelet sequestration studies, a hypothesized predictive test, have adopted heterogeneous methods and varied widely with regard to power. By studying patients with primary ITP who underwent autologous 111In-labelled platelet sequestration studies at Barts and The London NHS Trust between 1994 and 2008, we evaluated the effectiveness of sequestration site in predicting short, medium, and long-term CR (platelet count > 100 x 109/l) to splenectomy through multivariate (gender, age at splenectomy, and mean platelet lifespan) logistic regression modelling. In total, 256 patients with primary ITP underwent scans; 91 (35 center dot 5%) proceeded to splenectomy. Logistic regression revealed significant adjusted odds ratios for CR of 7 center dot 47 (95% confidence interval [CI], 1 center dot 89-29 center dot 43) at 1-3 months post-splenectomy, 4 center dot 85 (95% CI, 1 center dot 04-22 center dot 54) at 6-12 months post-splenectomy, and 5 center dot 39 (95% CI, 1 center dot 34-21 center dot 65) at last follow-up (median: 3 center dot 8 years [range: 0 center dot 5-13 center dot 1 years]) in patients with purely or predominantly splenic versus mixed or hepatic sequestration. These findings demonstrate the utility of autologous 111In-labelled platelet sequestration studies as an adjunct predictive instrument prior to splenectomy.