Response and remission after first-line corticosteroid therapy in primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease characterised by an isolated thrombocytopenia of <100 × 109/L in the absence of identifiable secondary causes. Treatment is indicated when the platelet count is <20 - 30 × 109/L, but may be commenced at higher platelet counts when the risk of bleeding is high. Corticosteroids are the backbone of initial treatment of ITP. There is a paucity of data in South Africa (SA) on the outcomes of newly diagnosed ITP patients treated with corticosteroids.

To describe the response, remission and clinical outcomes of newly diagnosed primary ITP patients on first-line corticosteroids.

This was a retrospective cohort study of 68 patients with a new diagnosis of ITP, seen at the Clinical Haematology Unit at Groote Schuur Hospital, Cape Town, SA, over a 5-year period (2016 - 2020). Demographic and clinical data were obtained from paper and electronic record systems. All participants with secondary causes were excluded. The initial platelet responses to corticosteroids and the final outcomes at last follow-up were determined. Initial platelet responses were classified into no response (NR), partial response (PR) and complete response (CR) in accordance with consensus definitions. Remission was defined as maintenance of a CR after being off corticosteroids for ≤6 months. Categorical variables were described by frequencies and percentages, while numerical variables were described by medians and interquartile ranges (IQRs) as data were non-parametric.

The majority of patients were female (88.2%) and the median (IQR) age at diagnosis was 36 (23.0 - 55.5) years. The female to male ratio was 7.5:1. Most (92.4%) patients responded to corticosteroids, with 74.2% achieving a CR and 18.2% achieving a PR. Only five patients failed to respond (7.6%). The median (IQR) time to achieve CR was 15 (8 - 25) days, and the median (IQR) time to achieve PR was 10.5 (8 - 22) days. Half of the patients went into remission. Following remission, two patients (6.1%) subsequently relapsed at day 344 and day 777, respectively. Hypertension and/or diabetes mellitus were newly diagnosed in 10.6% of patients.

Corticosteroids are effective first-line therapy for ITP, but are not remission-inducing in all patients. For those patients progressing to chronic ITP, there is a need to investigate cost-effective treatment. Some patients are at high risk of developing new hypertension and diabetes mellitus on corticosteroids, and should be monitored.