Predicting Macrophage Activation Syndrome in Pediatric Systemic Lupus Erythematosus Patients at Diagnosis

Maya Gerstein¹, Roberto Ezequiel Borgia², Brian Feldman¹, Deborah M. Levy³, Sharon Sukhdeo⁴, Susanne M. Benseler⁵, Lawrence W.K. Ng¹, Mohamed Abdelhaleem⁶, Earl D. Silverman² and Linda T Hiraki⁷, ¹Rheumatology, The Hospital for Sick Children, Toronto, ON, Canada, ²Division of Rheumatology, The Hospital for Sick Children, Toronto, ON, Canada, ³Rheumatology, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada, ⁴Rheumatology, The Hospital For Sick Children, Toronto, ON, Canada, ⁵Rheumatology, Alberta Children's Hospital, University of Calgary, Calgary, AB, Canada, ⁶Department of Paediatric Laboratory Medicine, Division of Haematopathology, The Hospital for Sick Children, Toronto, ON, Canada, ⁷The Hospital for Sick Children, Toronto, ON, Canada

Meeting: 2014 ACR/ARHP Annual Meeting

Keywords: Decision analysis, diagnostic criteria and macrophage activation syndrome, SLE

Session Information

Title: Pediatric Rheumatology - Clinical and Therapeutic Aspects: Pediatric Lupus, Scleroderma and Myositis (ACR)

Session Type: Abstract Submissions (ACR)

Background/Purpose

It can be difficult to differentiate macrophage activation syndrome (MAS) from active pediatric systemic lupus erythematosus (pSLE). However, this differentiation is in determining correct treatment decisions. The purpose of this study is to generate a decision tree for the recognition of MAS in newly diagnosed pSLE and test the performance of these proposed criteria in an independent pSLE cohort.

Methods

A retrospective cohort study of consecutive patients requiring admission to SickKids Hospital with newly diagnosed, active pSLE between January 2002 and July 2007 (training cohort) was performed. All patients met ≥4 /11 ACR criteria. Data collection on: 1) Clinical features including fever, CNS dysfunction, splenomegaly, hepatomegaly and hemorrhage; 2) laboratory parameters; CBC, ESR, CRP, C3, C4, ferritin, AST, ALT, LDH, albumin, bilirubin, triglycerides, LDL, HDL, urea, creatinine, sodium, coagulation parameters including INR, PTT, fibrinogen and D-Dimer, and soluble IL-2 receptor (sIL-2R) and CD163. Patients were assigned to one of 2 cohorts exclusively (MAS/non-MAS). Putative predictor variables were compared between cohorts. A decision tree analysis for diagnosis of MAS in pSLE was constructed using recursive partitioning, and decision rules were subsequently applied to an independent cohort of newly diagnosed, active pSLE diagnosed and admitted to SickKids between July 2007 and July 2013 (testing cohort) to determine the sensitivity and specificity of the proposed criteria

Results

The training cohort consisted of 56 pSLE patients: 9 (16%) diagnosed with MAS and 47 non-MAS patients. Splenomegaly was more common in the non-MAS cohort, with no other differences in clinical characteristics between cohorts. Of all the available laboratory data, ALT ≥ 45 units/L, neutrophils < 1.65 x 10³/mm³ and ferritin ≥ 836 µg/L identified 55% of the patients with MAS (R² = 0.75) with 100% specificity. The testing cohort consisted of 9 (20%) MAS and 32 non-MAS pSLE patients. The proposed thresholds for ALT, neutrophil count and ferritin demonstrated a sensitivity of 67% and specificity of 94% in discriminating MAS from nonMAS patients.

Conclusion

None of the clinical features differentiated pSLE patients with and without MAS. Using all laboratory data proposed to be elevated in MAS and decision tree analysis demonstrated that ALT, neutrophil count and ferritin had excellent specificity and adequate sensitivity for distinguishing MAS from active SLE at diagnosis in the both the testing and validation cohorts. This is a first step in improved recognition of MAS among pSLE patients. Future analyses are planned to further refine methods in distinguishing these two groups.

Disclosure:

M. Gerstein,
None;

R. E. Borgia,
None;

B. Feldman,
None;

D. M. Levy,
None;

S. Sukhdeo,
None;

S. M. Benseler,
None;

L. W. K. Ng,
None;

M. Abdelhaleem,
None;

E. D. Silverman,
None;

L. T. Hiraki,
None.

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