Predictive Factors of Relapse for Primary Immune Thrombocytopenia in Adults: A Single-Center Retrospective Cohort Analysis

Background: Predicting relapse after achieving response for adult immune thrombocytopenia(ITP) is an unsolved problem. Our study aimed to identify robust and simple pre-treatment clinical factors that can predict relapse in adult patients with ITP.

Methods: We censored all medical records of adult patients with primary newly diagnosed ITP hospitalized in our center from 2011 to 2021. Treatments were administered as clinically indicated.Clinical follow-up data were obtained from telephone interviews and electronic medical records. Only patients who achieved response were included in the study. Relapse referred to the first relapse event after achieving response. Statistical analyses were performed using SAS, version 9.4 (SAS Institute). Univariate Cox and Multi-adjusted Cox regression with stepwise selection were performed to identify risk factors associated with relapse.

Results: A total of 281 patients were enrolled in our cohort study. During hospitalization, 254 (90.4%) received first-line therapy (glucocorticoid, intravenous immunoglobulin), 121 (43.1%) received second-line therapy (rituximab, thrombopoietic drugs). Patients were followed up for a median period of 61(9-162) months. There were 145 (54.3%) achieved sustained response for at least one year and 63 (43.8%) for at least five year. During the follow-up period, 145 (51.6%) developed a relapse event, of whom the median time between response to relapse was 1.16(0.03-96) months. The median follow-up time for relapse-free patients at the end of the analysis was 57(10-136) months. Multivariate analysis revealed that drinking (hazard ratio [HR], 2.027, 95%CI, 1.316-3.121), insidious onset (HR, 1.966, 95%CI, 1.315-2.939), lower platelets count before treatment (HR, 1.041, 95%CI, 1.012-1.071), ALT＞35U/L (HR, 1.803, 95%CI, 1.197-2.716) and CD3⁺CD8⁺T cell/lymphocyte＞39% (HR, 1.919, 95%CI, 1.144-3.218) were independently associated with relapse.

Conclusion: Adult ITP patients have a low sustained response rate and high relapse rate. In this study, we found that drinking, insidious onset, lower platelets count before treatment, ALT＞35U/L and CD3⁺CD8⁺T cell/lymphocyte＞39% were independent predictors for ITP relapse. Next, we will apply these metrics to build a relapse prediction model, which allows clinicians to estimate individual relapse risk as well as sheds new light on ITP treatment.

Keywords: immune thrombocytopenia, relapse, predictive factors

No relevant conflicts of interest to declare.