Optimising Care for Haemophagocytic Lymphohistiocytosis in District General Hospitals: Best Practice Insights and Review of Literature.

Haemophagocytic lymphohistiocytosis (HLH) is a hyper-inflammatory syndrome characterised by widespread, uncontrolled T cell and histiocyte activation with accompanying cytokine storm. It can be inherited or acquired, with acquired forms triggered by infection, malignancy or autoimmune disease. There is high mortality, with patients commonly requiring critical care support. HLH is a relatively rare condition (though it is likely underdiagnosed), and there is an incomplete understanding of its pathogenesis, diagnosis and optimal management. As such, HLH presents a challenge to the critical care physician, particularly in a non-specialist centre. In our District General Hospital (DGH) intensive therapy unit, we experienced an unusually high volume of HLH cases in a short period. By presenting this case series and our improvement strategies, we aim to distil key lessons to other centres to improve the understanding of HLH for critical care physicians. There were seven confirmed cases of HLH between January 2022 and August 2024. We analysed each case, in turn, documenting the initial symptomatology, blood test results, including ferritin, and when specialist teams such as haematology and critical care became involved. We then noted when HLH treatment was started and the outcome of each case. We found that implementing a protocol to encourage early requests of an HLH blood test panel and, thereafter, early review and input by the local haematology teams, as well as critical care input for any patient with suspected HLH, improved patient outcomes: two patients died during admission pre-intervention. However, none of the patients died within their admission after our interventions. We also found that pharmacy input to ensure the emergency stock of medications used to treat HLH allowed more prompt administration of HLH treatment. Although the cornerstone of management for the critical care physician includes supportive care and organ support, HLH-specific treatments targeting the underpinning inflammation and the cytokine storm are also pivotal to controlling the disease process. Early escalation to the haematology team based on abnormally high ferritin levels and early critical care input was the cornerstone of the pathway we developed in our hospital. This system that has been developed will stand to be useful in other DGHs where HLH remains an unfamiliar condition that carries a high mortality rate.