OBJECTIVESImmune thrombocytopaenia (ITP) is a rare autoimmune disorder characterized by low platelet count and increased risk of bleeding. This study aimed to be the first publication to characterize the economic burden of bleeding events in patients with ITP in the UK.METHODSWe performed a microcosting analysis to estimate the costs associated with bleeding events in patients with ITP. Healthcare resources utilized in the management of bleeds of different severity were costed using well-established UK cost sources. The results were validated through semi-structured interviews with clinical experts.RESULTSThe severity of bleeding events was classified into four categories, ranging from bleeding managed at home, through mild bleeding managed in the outpatient or day case setting, to serious and life-threatening bleeding events requiring inpatient admission. Total medical costs per event ranged from £2,930 for managing a mild bleeding event, through £16,711 for a serious bleeding event to £32,461 for a life-threatening event. The major cost driver for mild and serious events were intravenous immunoglobulin (IVIg) costs, amounting to £1,614 and £8,071 for the two severity categories, respectively. For life-threatening events, the costs of intensive care unit stay (£9,089) exceeded those of IVIg (£8,071).CONCLUSIONReal-world costs of managing bleeding in patients with ITP in the UK are substantial and greater than costs set only based on the UK NHS Tariff. Mitigating the risk of bleeding in patients with ITP is likely to yield not only clinical advantages for patients but also offer substantial cost savings to the health system.