POS1187 CATASTROPHIC ADULT ONSET STILL DISEASE: FREQUENCY, PHENOTYPE, AND VALUE OF HLH/MAS VS SOFA SCORE: INSIGHT FROM AN INTERDISCIPLINARY SINGLE CENTER STUDY
Authors: T. Dietrich, C. Bretonniere, C. Darrieutort Laffite, N. Piriou, S. Pattier, J. Graveleau, A. Espitia-Thibault, P. Pottier, C. Agard, E. Canet, A. Neel
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Adult Onset Still's Disease (AOSD) is an autoinflammatory condition characterized by a clinical triad including fever, arthralgia and evanescent rash. Most cases are not life-threatening (mortality ~ 1-3%). However, many complications are reported (shock, respiratory failure, myocarditis, tamponade, coagulopathy, hepatitis and macrophage activation syndrome [MAS]…). Despite their possible co-occurrence, these have mostly been studied separately. We recently reported the spectrum of AOSD complicated by organ failure and coined the term "Catastrophic AOSD" (CAOSD)[1,2], which has been then adopted by others [3,4]. CAOSD mostly occur at disease onset and is typically misdiagnosed as sepsis. MAS is the most classical complication of AOSD. Several authors have attempted to define the boundaries between AOSD and AOSD-related MAS using several score such as the Hscore, the EULAR/ACR/PRINTO 2016 and the MS score. Whether these scores help to capture the full spectrum of CAOSD remains unclear. <h3>Objectives:</h3> The aim of this study are 1) to report on the frequency and phenotype of CAOSD among a single center inception cohort of AOSD and 2) to study the value of different MAS/HLH scores, the Pouchot's score and compare them to a sepsis prognosis score (SOFA). <h3>Methods:</h3> Retrospective analysis of AOSD patients seen at Nantes University Hospital (NUH) for a first flare between 2000 and 2022. Cases were classified as benign or catastrophic AOSD. The latter were defined by the recourse to intensive care (ICU). Clinical and biological data along with HScore, MS score, EULAR/ACR/PRINTO 2016 score, Pouchot's systemic score and SOFA score were collected at the time of hospitalization and at the time of organ failure onset. <h3>Results:</h3> Sixty-six patients were included, among which 17 had CAOSD (25,8%). One patient (1,5%) died. Cardio-circulatory (17%), respiratory (10%) and hematologic dysfunctions (11%) were the main organ complications. At the time of organ failure, CAOSD presented with more serositis, splenomegaly, cytolysis, higher ferritin, LDH, conjugated bilirubin and CRP levels, lower hemoglobin, glycosylated ferritin and platelet levels and a shorter prothrombin time. The delay between symptom onset and hospitalization was shorter for patients who developed CAOSD (Figure 1). Patients with CAOSD had higher levels of ferritin, liver enzymes and CRP, as well as lower prothrombin times on admission to hospital. On the other hand, no significant difference was noted regarding hemoglobin, neutrophil and platelet counts. SOFA score outperformed the Pouchot systemic score and all MAS/HLH scores to identify or predict CAOSD (Figure 2). <h3>Conclusion:</h3> One quarter of patients with new onset AOSD develop CAOSD. Mortality remains low, which may be explained by prompt interdisciplinary management. CAOSD is a hyper-acute form of AOSD, not the consequence of diagnostic delay. Organ dysfunctions are mainly cardio-circulatory, pulmonary and hematologic but unlike in rHLH (reactive hemophagocytic lymphohistiocytosis), cytopenia are rare. Consistently, MAS/rHLH scores do not capture the full spectrum of CAOSD. The ability of the SOFA score to predict and/or identify CAOSD is consistent with the fact that the overall clinical picture of CAOSD is closest to sepsis than to hemaphocytic syndrome. First line hospital physicians (including intensivists from polyvalent, cardiac and pulmonary ICU) should be made aware of this pitfall. <h3>REFERENCES:</h3> [1] Néel A, <i>et al</i>. Crit Care. 2018;22:88. [2] Wahbi A <i>et al</i>. Arthritis Res Ther. 2021;23:256. [3] Dillemans L, et al. Clin Immunol. 2023;257:109815. [4] Ruscitti P <i>et al</i>. RMD Open. 2023;9:e003419. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>