Diagnostic Use of Testing for Novel Murine Autoantibodies for Sjögren Disease in the Rheumatology Outpatient Setting

The goal was to assess the diagnostic performance of three novel autoantibodies (NA) for Sjögren disease (SjD) by comparing NA prevalence in patients with SjD, other autoimmune rheumatic diseases (ARDs), nonspecific chronic sialadenitis (CS), and controls.

We identified rheumatology outpatients with confirmed SjD, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), CS, and healthy controls. Participants underwent serum testing for antibodies to salivary gland protein 1 (SP-1), parotid secretory protein, and carbonic anhydrase-6 (CA-6). Participants with SjD, CS, and controls also underwent testing of saliva. Receiver operating characteristic (ROC) curve C-statistics along with sensitivity, specificity, positive, and negative likelihood ratios were calculated for each serum autoantibody for SjD vs CS or controls.

Among the 468 patients screened, 444 were analyzed, including cohorts with SjD (n = 149), SLE (n = 70), SSc (n = 56), RA (n = 73), CS (n = 31), and control patients (n = 65). There was no statistical difference (P = 0.80) in the presence of one or more NA in the serum of patients with SjD compared with participants with other ARDs, CS, or control patients. ROC curves demonstrated poor discriminative ability for SjD versus CS or control patients for any positive NA (0.47) or any individual NA (range 0.44-0.53). The positive likelihood ratio for having any positive novel autoantibody was 1.04 and 0.83 for SjD vs CS or control patients, respectively.

Testing serum for NA demonstrated a poor ability to distinguish patients with SjD from control patients or those with CS or other ARDs. This serum autoantibody panel is not likely to be useful as a diagnostic test for SjD.