Response to Anti D immunoglobulin in Adults with Chronic Immune Thrombocytopenic Purpura in a Minority Cohort with Long Term Follow up.

Immune Thrombocytopenic Purpura (ITP) is a common hematological disorder. We sort to characterize the risk profiles and efficacy of anti D immunoglobulin in chronic ITP in a largely minority cohort.

31 patients (pts) with chronic immune thrombocytopenic purpura treated 2003-2008 were studied as a retrospective cohort for clinical presentation, prognostic characteristics, time to next therapy and long term survival. Prognostic factors, time to relapse and overall survival was analyzed using fisher's exact test, logistic regression, Kaplan Meier survival analysis and Cox Proportional Hazards model.

31 pts 19(61.3%) female and 12(38.7%) male. 11 (35.5%) African Americans, 12(38.7%) Hispanic, 5 (16.2%) Asians and 3 (7.8%) Caucasians. Median age at diagnosis was 44 yrs (21-66). 25 (80.5%) were HIV negative and 6 (19.5%) had HIV. 16 (51.6%) had O positive blood group, 9 (29.6%) had A positive and 4 (12.9%) had B positive. The median number of co-morbidities at diagnosis was 1(0-6). Median age at which anti D immunoglobulin was initiated was 45 yrs. Pt had received a median of 3 (2-6) therapies prior to anti D therapy. All patients had received steroids, 17 (54.8%) had immunoglobulin therapy, 2 (6.5%) had vincristine and 6(19.3%) had splenectomy prior to anti D therapy. The median duration to anti D therapy was 6 months (0-228). Anti D therapy was given in the dose of 50-75mcg/kg IV weekly. Median number of doses given was 2 (1-7) doses.

The response rate was 64.5%. Response was defined as Complete response, platelet count of > 100 × 10⁹/L, Partial response >30 × 10⁹/L. 17 (54.8%) achieved complete response, 3 (9.7%) achieved partial response. 11(35.5%) did not respond. Median time to relapse was 4 months (0-79). 9 (29%) achieved a complete response for over a year.

Pt with HIV (p=0.013), O blood group (p=0.030) had a significant poor response to anti D therapy on univariate analysis. Pt with HIV (p=0.035) had poor response to therapy on multivariate analysis. O blood group (p=0.001), HIV (p=0.016), > 2 lines of therapy (p=0.007), one dose of anti D (0.037) were associated with shorter time to progression on univariate analysis. On multivariate analysis prior immunoglobulin administration (p=0.039), >2 lines of therapy (p=0.004) and single dose of anti D immunoglobulin (p=0.039) were associated with shorter time to progression.

Anti D immunoglobulin had a response rate of 64.5% which is similar to other studies. About 29% of patients had a complete response for over a year. Pts who not received anti D immunoglobulin, HIV negative and early anti D administration had the best response and longer time to progression.

No relevant conflicts of interest to declare.