Novel Diagnostic Test Demonstrates Clinical Utility in Systemic Lupus Erythematosus

Multianalyte assay panel testing may be an effective tool for facilitating the diagnosis of systemic lupus erythematosus (SLE), according to study results published in Lupus Science & Medicine.

Researchers conducted a multicenter, randomized, prospective study comparing the physician-assessed diagnostic likelihood of SLE resulting from standard diagnosis laboratory testing compared with a multianalyte assay panel with cell-bound complement activation products (MAP/CB-CAPs).

In total, 145 patients were enrolled across 32 sites between July 2017 and December 2018. Patients were randomly assigned 1:1 to receive either standard diagnosis laboratory or MAP/CB-CAPs testing. At enrollment, SLE likelihood was similar in both groups (1.42±0.06 vs 1.46±0.06 points, respectively; P =.68).

Investigators noted a significant decrease in posttest SLE likelihood regardless of randomization arm, with a lower likelihood among patients randomly assigned to the MAP/CB-CAPs group compared with the standard diagnosis group (-0.44±0.10 vs -0.19±0.07 points, respectively; P =.027). This decrease remained significant at the 12-week follow-up (-0.61±0.10 vs -0.31±0.10 points; P =.025). At 12 weeks, there was a significant decrease in SLE likelihood in the MAP/CB-CAPs group compared with the standard diagnosis group (56% vs 37%; difference, 19%; P =.031).

Overall, results indicated that there was lower likelihood of SLE detectable among patients who tested negative for MAP/CB-CAPs compared with those who underwent standard diagnosis testing (60% vs 37%; difference, 23%; P =.012). None of the patients in the MAP/CB-CAPs group had higher posttest likelihood of SLE in conjunction with negative test results.

At study enrollment, patients who presented with a positive MAP/CB-CAPs test had higher physician global assessment compared with those who achieved negative test results (1.44±0.14 vs 1.10±0.05; P =.030). At 12 weeks follow-up, a higher improvement in physician global assessment was noted in the MAP/CB-CAPs vs the standard diagnosis laboratory testing arm (-0.39±0.08 vs -0.29±0.06). Compared with the MAP/CB-CAPs group, more patients in the standardized diagnosis group (6% vs 10%) received either prednisone or hydroxychloroquine therapy.

In addition, among patients in the MAP/CB-CAPs group, a positive test result was associated with increased EQ5D-5 level index scores from study enrollment to visit 2 and greater improvements in patients who tested positive and randomly assigned to the standardized diagnosis arm (mean, 0.099±0.046 vs -0.008±0.050; P =.049).

Limitations included the short time frame of the study, and thus, limited data collection.

“Our data suggest that MAP/CB-CAPs testing [have] clinical utility in facilitating SLE diagnosis and treatment decisions,” the researchers concluded.

Disclosure: This study was supported by Exagen. Please see the original reference for a full list of authors’ disclosures.

Reference

Wallace DJ, Alexander RV, O’Malley T, et al. Randomized prospective trial to assess the clinical utility of multianalyte assay panel with complement activation products for the diagnosis of SLE [published online September 19, 2019]. Lupus Sci Med. doi:10.1136/lupus-2019-000349