Consensus recommendations for the diagnosis and management of hemophagocytic lymphohistiocytosis in the Gulf Cooperation Council: a modified Delphi approach.

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening hyperinflammatory syndrome associated with high mortality. Although international recommendations largely guide clinical practice in the Gulf Cooperation Council (GCC) region, the region faces distinct challenges. Therefore, this first GCC-specific consensus study was conducted to develop practical recommendations for the diagnosis and management of HLH in both adult and pediatric patients. Methods: A modified Delphi methodology was used. A multidisciplinary panel of 15 experts from all GCC countries, comprising 5 steering committee members and 10 extended panel members, was recruited through purposive sampling. A targeted literature review was conducted, and the evidence was graded using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework. Based on the literature review and expert clinical perspectives, 8 clinical domains were selected and 40 gap statements were developed. Following review and revision by the steering committee, the final statements were disseminated to all panel members. Agreement was assessed using a five-point Likert scale, with ≥80% agreement or disagreement prespecified as the threshold for consensus. Results: All 15 panel members completed the voting process. All 40 statements achieved consensus in round 1, with 80-100% agreement. The recommendations emphasize that HLH assessment should begin as soon as clinical suspicion arises, and that HLH-2004 criteria and HScore should support, rather than replace, clinical judgment. Evaluation should proceed in parallel with investigation for infectious, malignant, rheumatological, and genetic triggers, while treatment should not be delayed in patients with severe or progressive disease. The panel highlighted the importance of early genetic assessment in infants, young children, patients without clear secondary triggers, and families with consanguinity or a suggestive family history. Treatment should be individualized according to age, disease severity, trigger, organ dysfunction, and treatment tolerance, with consideration of targeted and salvage therapies in refractory, relapsed, or treatment-intolerant HLH. Early referral to centers with intensive care, advanced diagnostics, and transplant capability should be prioritized. Conclusions: These consensus recommendations provide a framework to harmonize HLH recognition, risk-adapted treatment, referral, transplant planning, and regional coordination in GCC countries. Future studies are needed to define regional epidemiology, genetic landscape, treatment responses, and outcomes.