Table 1.
Demographic and clinical characteristics of patients with primary Sjögren’s syndrome (pSS) included in the discovery cohort and the replication cohort.
| Discovery cohort (Uppsala, Sweden) | Replication cohort (Stavanger, Norway) | Total | |
|---|---|---|---|
| Individuals, n | 100 | 48 | 148 |
| Age at DNA sampling, years, mean (±s.d.) | 56.1 (±13.7) | 56.7 (±13.7) | 56.3 (±13.6) |
| Female, n (%) | 89 (89%) | 41 (85%) | 130 (88%) |
| Autoantibody frequency‡, n/available (%) | |||
| SSA | 72/100 (72%) | 38/48 (79%) | 110/148 (74%) |
| Ro52 | 51/82 (62%) | n.a. | 51/82 (62%) |
| Ro60 | 52/82 (63%) | n.a. | 52/82 (63%) |
| SSB | 41/100 (41%) | 21/48 (44%) | 62/148 (42%) |
| ANA | 76/100 (76%) | 41/48 (85%) | 117/148 (79%) |
| Positive for any of the included autoantibodies | 88/100 (88%) | 43/48 (90%) | 131/148 (89%) |
| DNAm IFN score | |||
| IFN score, mean (±s.d.) | 5.6 (±4.3) | 6.0 (±4.9) | 5.8 (±4.5) |
| High IFN score§, n (%) | 57 (57%) | 30 (63%) | 87 (59%) |
| Clinical manifestations¶, n/available (%) | |||
| Focus score, mean (±s.d, n available) | 3.6 (±3.2, n=62) | 2.5 (±2.8, n=48)** | 3.1 (±3.1, n=110) |
| GC formation | 11/51 (22%) | 5/20 (25%) | 16/71 (23%) |
| Leucopenia | 33/98 (34%) | 23/48 (48%) | 56/146 (38%) |
| P-IgG > 15g/L | 46/90 (51%) | 19/37 (51%) | 65/127 (51%) |
| C3 below normal limit | 6/72 (8%) | 7/47 (15%) | 13/119 (11%) |
| C4 below normal limit | 5/18 (28%) | 7/45 (16%) | 12/63 (19%) |
| Raynaud’s | 33/99 (33%) | 20/48 (42%) | 53/147 (36%) |
| Arthritis | 17/99 (17%) | 4/48 (8%) | 21/147 (14%) |
| Purpura | 8/99 (8%) | 2/48 (4%) | 10/147 (7%) |
| Lymphadenopathy | 22/99 (22%) | 6/48 (13%) | 28/147 (19%) |
| Hypothyroidism | 24/99 (24%) | 11/48 (23%) | 35/147 (24%) |
| Lymphoma | 14/100 (14%) | 1/48 (2%)* | 15/148 (10%) |
| Medication at DNA sampling, n (%) | |||
| Prednisolon | 7 (7%) | 7 (15%) | 14 (9%) |
| Antimalarials | 14 (14%) | 16 (33%) | 30 (20%) |
| Immunosuppressants† | 4 (4%) | 1 (2%) | 5 (3%) |
| Biologics# | 0 | 1 (2%) | 1 (0.7%) |
‡Autoantibody status from medical records at nearest time point to DNA sampling.
§High IFN score defined as DNAm IFN score > meanctrl +2s.d.ctrl, >4.4.
¶Clinical manifestations presented ever.
†Azathioprine (n=2), mycophenolate mofetil (n=1), chlorambucil (n=1), cyclophosphamide (n=1).
#Infliximab (n=1).
Frequencies between discovery cohort and replication cohort compared with X2-test or, if applicable, with Fisher’s exact test. Continuous variables between groups tested using Mann-Whitney U. *P < 0.05, **P < 0.01.
ANA, antinuclear antibodies; C3, complement component 3; C4, complement component 4; DNAm, DNA methylation; GC, germinal center; IFN, interferon; n.a., not available; s.d., standard deviation; SSA, anti-Sjögren’s syndrome antigen A antibodies (Ro52 and/or Ro60); SSB, anti-Sjögren’s syndrome antigen B antibodies (La).