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

Author

Wallace DJ1, Alexander RV2, O'Malley T2, Khosroshahi A3, Hojjati M4, Loupasakis K5, Alper J6, Sherrer Y6, Fondal M6, Kataria R7, Powell T2, Ibarra C2, Narain S8, Massarotti E9, Weinstein A2,10, Dervieux T2. Lupus Sci Med. 2019 Sep 19;6(1):e000349. doi: 10.1136/lupus-2019-000349. eCollection 2019.

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.