The Avise Lupus Test and Cell-bound Complement Activation Products Aid the Diagnosis of Systemic Lupus Erythematosus
James Mossell1, John A. Goldman2, Derren Barken3, Roberta Vezza Alexander3, *
1 Tift Regional Medical Center, Tifton, GA, USA
2 Emory St. Joseph’s Hospital, Atlanta, GA, USA
3 Exagen Diagnostics, Inc., Vista, CA, USA
Systemic lupus erythematosus (SLE) is a multifaceted disease, and its diagnosis may be challenging. A blood test for the diagnosis of SLE, the Avise Lupus test, has been recently commercialized and validated in clinical studies.
To evaluate the use of the Avise Lupus test by community rheumatologists.
The study is a longitudinal, case-control, retrospective review of medical charts. Cases had a positive test result, and controls had a negative result; all patients were anti-nuclear antibodies (ANA) positive but negative for SLE-specific autoantibodies. Features of SLE, diagnosis, and medications at two time points were recorded.
Twenty of the 23 cases (87%) and 4 of the 23 controls (17%) were diagnosed with SLE (sensitivity=83%; specificity=86%). More cases than controls (43% vs. 17%) fulfilled 4 American College of Rheumatology (ACR) classification criteria of SLE. Sensitivity of the test was significantly higher than the ACR score (83% vs. 42%, p=0.006). A higher percentage of patients who met the classification criteria had elevated cell-bound complement activation products (CB-CAPs) compared to patients who did not. Anti-rheumatic medications were used in a higher percentage of cases than controls (83% vs. 35% at baseline, p=0.002), suggesting that cases were treated more aggressively early on.
A positive Avise Lupus test result aids in formulating a SLE diagnosis when diagnosis based on standard-of-care tests and clinical features may be challenging, and impacts patient management. Prospective studies will be performed to better evaluate the clinical utility of the test and of CB-CAPs as biomarkers of SLE.
Keywords: Biomarkers, Case-control study, Diagnostic test, Medical chart review.
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* Address correspondence to this author at the Exagen Diagnostics, Inc., 1261 Liberty Way, Vista, CA 92081, USA; Tel: 760-477-5277; Fax 760-560-1515; E-mail: firstname.lastname@example.org