Demographics of participants
| Peptidome array and internal validation (n=16) | |||||||
| SSA− SjD (n=8) | Control (n=8) | ||||||
| Age mean (SD) | 58 (12) | 59 (10) | |||||
| Female | 8 (100) | 8 (100) | |||||
| White | 8 (100) | 8 (100) | |||||
| Hispanic | 0 | 0 | |||||
| Platelet (k/µL) | 260 (45) | ||||||
| ANA positive (≥1:320) | 4 (50) | ||||||
| IgG mg/dL mean (SD) | 1088 (384) | ||||||
| RF positive | 1 (13) | ||||||
| Anti-SSB positive | 1 (13) | ||||||
| External validation (n=192) | |||||||
| SSA− SjD (n=76) | SSA+ SjD (n=75) | Autoimmune-feature control (n=41) | Sicca-control (n=75) | SLE (n=20) | RA (n=20) | P value | |
| Age mean (SD) | 55 (12) | 54 (12) | 56 (12) | 55 (12) | 53 (11) | 55 (13) | 0.98 |
| Female | 65 (86) | 65 (86) | 36 (88) | 64 (85) | 19 (95) | 18 (90) | 0.84 |
| Race | <0.0001 | ||||||
| White | 37 (49) | 34 (45) | 19 (46) | 33 (44) | 16 (80) | 19 (95) | |
| Asian | 31 (41) | 30 (39) | 15 (37) | 30 (40) | 1 (5) | 0 | |
| African | 0 | 4 (5) | 0 | 4 (5) | 3 (15) | 1 (5) | |
| Hispanic | 8 (11) | 8 (11) | 7 (17) | 8 (11) | 0 | 0 | |
| SLE diagnosis* | 0* | 3 (4)* | 2 (5)* | 1 (1)* | 20 (100)† | 0 | 0.13 |
| RA diagnosis* | 14 (18)* | 3 (4)* | 6 (15)* | 3 (4)* | 0 | 20 (100)† | 0.004 |
| Clinical metrics | |||||||
| OSS ≥5 | 56 (76) | 64 (84) | 16 (39) | 20 (27) | <0.0001 | ||
| Schirmer’s ≤5 mm | 39 (53) | 49 (65) | 10 (26) | 22 (32) | <0.0001 | ||
| UWS ≤5 mL/5 min | 52 (68) | 51 (67) | 16 (39) | 31 (41) | 0.0002 | ||
| Lab metrics | |||||||
| ANA ≥1:320 | 22 (29) | 52 (68) | 12 (29) | 0 | <0.0001 | ||
| SSA positive | 0 | 75 (100) | 0 | 0 | |||
| SSB positive | 2 (3) | 42 (55) | 2 (5) | 2 (3) | <0.0001 | ||
| IgG (mg/dL) mean (SD) | 1343.2 (764.8) | 1826.4 (831.8) | 1357.10 (703.4) | 1058.3 (342.5) | <0.0001 | ||
| Platelet (k/µL) mean (SD) | 248.2 (65.5) | 231.4 (55.9) | 257.9 (72.6) | 269.1 (85.9) | 0.01 | ||
| RF positive | 31 (41) | 49 (64) | 27 (66) | 0 | <0.0001 | ||
| Histopathology | |||||||
| Focus score ≥1 | 76 (100) | 55 (72) | 9 (22) | 0 | <0.0001 | ||
Control=participants without autoimmune disease; sicca-controls=participants with symptoms or signs of dryness but negative ANA, RF, SSA and FS <1; autoimmune-feature controls=participants with symptoms/signs of dryness and ANA ≥1:320, positive RF or FS ≥1 on labial salivary gland biopsy but not meeting 2016 ACR/EULAR SjD criteria.
Values represent n (%) unless otherwise indicated. Continuous variable significance was measured by ANOVA and categorical by χ2 likelihood ratios.
*Diagnoses were confirmed by treating physician but not independently confirmed by the SICCA registry.
†University of Wisconsin patients with physician-diagnosed SLE or RA.
ACR, American College of Rheumatology; ANA, antinuclear antibody; ANOVA, analysis of variance; OSS, ocular staining score; RA, rheumatoid arthritis; RF, rheumatoid factor; SICCA, Sjögren’s International Collaborative Clinical Alliance; SjD, Sjӧgren disease; SLE, systemic lupus erythematosus; UWS, unstimulated whole salivary flow.