Background/Purpose: Rapid identification of hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) coupled with a multidisciplinary approach to management is essential to improve patient outcomes. We describe our experience with a newly instituted Evidence Based Guideline (EBG) for HLH/MAS at Boston Children’s Hospital (BCH).

Methods: A diagnostic and therapeutic algorithm for HLH/MAS was developed at BCH based on literature review and expert opinion. The resulting EBG was activated at BCH in 1/2018 with the goal to review quality metrics after implementation. An electronic medical record (EMR) search algorithm (patients with an oncology and/or rheumatology note, fever ≥38.2C, and ferritin ≥500ng/mL) was developed to retrospectively identify all hospitalized patients in the EBG from 1/2018 to 4/2019. The selected medical records were then reviewed by an attending rheumatologist, and clinical data were entered into a REDCap database. Subjects with a previously known diagnosis of HLH/MAS before hospital admission were excluded.

Results: Twenty-seven patients (12 girls, 15 boys) with an average age of 8.8 years were identified by house staff as potential HLH/MAS patients and rheumatology was consulted for management per the EBG. After rheumatology consult, there was concern for HLH/MAS in 17 patients (63%), and a diagnostic evaluation was initiated.  Ultimately, 10 patients were diagnosed with HLH/MAS by the treating team. Of these, 6 met HLH 2004 criteria, and 9 met the 2016 MAS classification criteria for systemic juvenile idiopathic arthritis (sJIA). The following underlying diagnoses were identified in the patients with HLH/MAS:  sJIA (n=3), systemic lupus erythematosus (n=1), malignancy (n=1), familial HLH type 2 (n=1), STAT2 deficiency (n=1), and congenital disorder of glycosylation type 2 defect (n=1).

These 10 patients were treated for HLH/MAS according to EBG guidelines. The most common first line treatments were IVIG (n=4), glucocorticoids (n=3), and anakinra (n=3). One patient was treated per the HLH2004 protocol. For treated patients, the average hospital stay was 29.9 days with a mean time from admission to HLH/MAS directed therapy of 3.2 days. Management guided by the EBG led to a mean fever duration of 6.0 days. Ferritin levels decreased by 50% during admission in 6 subjects, and the mean time to this decrease was 5.3 days. Eight patients required higher level care, and mortality was reported in 1 patient during the hospital stay.

Conclusion: Implementation of EBG for HLH and MAS was associated with rapid initiation of HLH/MAS directed therapy (3.2 days after admission) and an overall survival rate of 90%, which compares favorably to historical reports. Further studies are needed to compare these outcomes to those from the pre-EBG implementation period to confirm improved quality of care.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/outcomes-of-an-evidence-based-guideline-for-the-treatment-of-hemophagocytic-lymphohistiocytosis-and-macrophage-activation-syndrome/