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Lupus Sci Med. 2019 Sep 19;6(1):e000349. doi: 10.1136/lupus-2019-000349. eCollection 2019.

Randomised prospective trial to assess the clinical utility of multianalyte assay panel with complement activation products for the diagnosis of SLE.

Author information

1
Cedars-Sinai Medical Center, Los Angeles, California, USA.
2
Exagen, Vista, Caifornia, USA.
3
Emory University, Atlanta, Georgia, USA.
4
Loma Linda University, Loma Linda, California, USA.
5
MedStar Washington Hospital Center, Washington, District of Columbia, USA.
6
Bendcare, Naples, Florida, USA.
7
Southern Ohio Rheumatology, Wheelersburg, Ohio, USA.
8
Northwell Health, Great Neck, New York, USA.
9
Brigham and Women's Hospital, Boston, Massachusetts, USA.
10
Georgetown University, Washington, DC, USA.

Abstract

Objective:

We compared the physician-assessed diagnostic likelihood of SLE resulting from standard diagnosis laboratory testing (SDLT) to that resulting from multianalyte assay panel (MAP) with cell-bound complement activation products (MAP/CB-CAPs), which reports a two-tiered index test result having 80% sensitivity and 86% specificity for SLE.

Methods:

Patients (n=145) with a history of positive antinuclear antibody status were evaluated clinically by rheumatologists and randomised to SDLT arm (tests ordered at the discretion of the rheumatologists) or to MAP/CB-CAPs testing arm. The primary endpoint was based on the change in the physician likelihood of SLE on a five-point Likert scale collected before and after testing. Changes in pharmacological treatment based on laboratory results were assessed in both arms. Statistical analysis consisted of Wilcoxon and Fisher's exact tests.

Results:

At enrolment, patients randomised to SDLT (n=73, age=48±2 years, 94% females) and MAP/CB-CAPs testing arms (n=72, 50±2 years, 93% females) presented with similar pretest likelihood of SLE (1.42±0.06 vs 1.46±0.06 points, respectively; p=0.68). Post-test likelihood of SLE resulting from randomisation in the MAP/CB-CAPs testing arm was significantly lower than that resulting from randomisation to SDLT arm on review of test results (-0.44±0.10 points vs -0.19±0.07 points) and at the 12-week follow-up visit (-0.61±0.10 points vs -0.31±0.10 points) (p<0.05). Among patients randomised to the MAP/CB-CAPs testing arm, two-tiered positive test results associated significantly with initiation of prednisone (p=0.034).

Conclusion:

Our data suggest that MAP/CB-CAPs testing has clinical utility in facilitating SLE diagnosis and treatment decisions.

KEYWORDS:

clinical utility; diagnosis; laboratory test; systemic lupus erythematosus

Conflict of interest statement

Competing interests: DW, AK, MH, KL, SN, JA, YS, MF, RK and EM have received research grants/consulting fees from Exagen. TD, RA, TO, TP, and CI are employed by Exagen. AW is consultant to Exagen.

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