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Original research
Randomised prospective trial to assess the clinical utility of multianalyte assay panel with complement activation products for the diagnosis of SLE
  1. Daniel J Wallace1,
  2. Roberta Vezza Alexander2,
  3. Tyler O'Malley2,
  4. Arezou Khosroshahi3,
  5. Mehrnaz Hojjati4,
  6. Konstantinos Loupasakis5,
  7. Jeffrey Alper6,
  8. Yvonne Sherrer6,
  9. Maria Fondal6,
  10. Rajesh Kataria7,
  11. Tami Powell2,
  12. Claudia Ibarra2,
  13. Sonali Narain8,
  14. Elena Massarotti9,
  15. Arthur Weinstein2,10 and
  16. Thierry Dervieux2
  1. 1Cedars-Sinai Medical Center, Los Angeles, California, USA
  2. 2Exagen, Vista, Caifornia, USA
  3. 3Emory University, Atlanta, Georgia, USA
  4. 4Loma Linda University, Loma Linda, California, USA
  5. 5MedStar Washington Hospital Center, Washington, District of Columbia, USA
  6. 6Bendcare, Naples, Florida, USA
  7. 7Southern Ohio Rheumatology, Wheelersburg, Ohio, USA
  8. 8Northwell Health, Great Neck, New York, USA
  9. 9Brigham and Women’s Hospital, Boston, Massachusetts, USA
  10. 10Georgetown University, Washington, DC, USA
  1. Correspondence to Dr Thierry Dervieux; tdervieux{at}exagen.com; Dr Daniel J Wallace; drdanielwallace{at}attunehealth.com

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.

  • systemic lupus erythematosus
  • clinical utility
  • laboratory test
  • diagnosis

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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Footnotes

  • Contributors DW, TD, AW, EM, RA, TP and TO designed the study. TD performed the analysis and wrote the first draft of the manuscript. RA and TO managed the clinical protocol. AW and EM designed the adjudication protocol and performed the adjudications. CI managed and supervised laboratory testing and quality. All authors participated to data collection and approved the final manuscript.

  • Funding This study was funded by Exagen.

  • 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.

  • Patient consent for publication Not required.

  • Ethics approval Protocol was approved by Institutional Review Boards.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.

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