Background/Purpose: The serum features of the cytokine storm induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are similar to those of hemophagocytic lymphohistiocytosis syndrome (HLH) which can be secondary to both SARS-CoV-2 infection as well as some autoimmune rheumatic diseases (ARDs). Whether patients with ARDs are at higher risk for hypercytokinemia induced by SARS-CoV-2 infection is unknown. The aim of this study is to compare the risk of cytokine storm during SARS-CoV-2 infection between patients with ARDs and those without using serum parameters of the H-score.

Methods: Patients with ARDs infected with SARS-CoV-2 were identified from the electronic medical records (EMR) of Hamad Medical Corporation, one of the participating centers in the COVID-19 Global Rheumatology Alliance Registry. Cases were age and sex matched (1:3) to controls who were non-ARD patients infected with SARS-CoV-2. HLH serum parameters included in the H-score; hemoglobin, white blood cells, platelets, ferritin, triglyceride, aspartate transaminase and fibrinogen were electronically captured from EMR within 18 days after a confirmed SARS-CoV-2 infection by a positive nasopharyngeal polymerase chain reaction swab test. The serum cut-offs as defined by the H-Score tool were used to calculate the final score. To explore the crude differences in serum HLH markers, other items of the H-Score; “known underlying immunosuppression”, “evidence of hepatosplenomegaly” and “HLH features in bone marrow aspirate” were recorded as zero. Independent Samples t-test was used to compare the mean H-Score between study groups.

Results: The study included 203 cases and 551 controls with a mean (SD) age of 45.3 (11.7) and 44 (12.5) years, respectively, p = 0.191. Majority of patients were female in both groups (122 [60.1%] vs. 297 [53.9%], p = 0.129).

The most common ARDs was rheumatoid arthritis in 86 cases (42.4%), followed by spondyloarthropathy in 33 (16.1%) and systemic lupus erythematosus in 31 (15.7%). Of these cases, 67% were on conventional synthetic disease modifying anti-rheumatic drugs (Cs-DMARDs), 15.8% on biological DMARDs and 4.9% on rituximab. About 83% of the ARDs group were in remission or low disease activity while 13% were in moderate or high disease activity.

The mean (SD) H-Score was significantly higher in ARDs group compared to controls (63.9 [25.4] vs. 58.9 [23.1], p = 0.038). The difference in H-Score between the study groups was more substantial when “known underlying immunosuppression” item was considered for ARDs group (81.9 [25.4] vs. 58.9 [23.1], p < 0.001).

Conclusion: Based on the serum markers of the H-Score tool used to estimate the risk of HLH, patients with ARDs have higher scores compared to patients without ARDs during SARS-CoV-2 infection. This might indicate that patients with ARDs are at higher risk for a cytokine storm induced by this infection. A study is needed to clinically correlate the H-score to infection outcomes and highlight the implications of these findings.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-laboratory-parameters-of-hemophagocytic-lymphohistiocytosis-syndrome-in-patients-with-autoimmune-rheumatic-diseases-infected-with-sars-cov-2-a-retrospective-comparative-study/