Characteristics of the study population
| ANA-positive (n=125) | ANA-negative (n=461) | P value | |
| Demographic characteristics | |||
| Age (years) | 33.00 (26.00–55.50) | 33.00 (26.50–47.50) | 0.469 |
| Gender (female, %) | 102/125 (81.60) | 342/461 (74.19) | 0.086 |
| Follow-up time (months) | 33.00 (18.00–54.00) | 38.00 (19.00–57.00) | 0.189 |
| Bleeding score | 3.3±1.6 | 2.8±2.0 | 0.081 |
| Baseline clinical features | |||
| Platelet count, ×109/L | 34.00 (10.00–64.75) | 46.00 (17.25–79.00) | 0.015 |
| Leucocyte, ×109/L | 6.47 (4.89–8.53) | 6.85 (5.30–9.16) | 0.196 |
| Neutrophils, ×109/L | 4.46 (3.09–6.78) | 4.52 (3.19–7.11) | 0.744 |
| Lymphocytes, ×109/L | 1.60 (1.15–2.15) | 1.60 (1.15–2.20) | 0.725 |
| Haemoglobin, g/L | 125.00 (114.00–137.00) | 127.00 (114.00–140.00) | 0.190 |
| Sedimentation rate, mm/hour | 21.00 (7.75–31.75) | 14.00 (7.00–27.50) | 0.254 |
| C reactive protein, mg/L | 1.19 (0.74–4.20) | 1.21 (0.73–3.19) | 0.944 |
| Anti-PAIgG positivity, n (%) | 23/50 (46.00) | 59/166 (35.54) | 0.182 |
| ENA positivity, n (%) | 48/121 (39.67) | 76/449 (16.93) | <0.001 |
| Anti-SSA positivity | 28/121 (23.14) | 31/449 (6.90) | <0.001 |
| Anti-Ro52 positivity | 26/121 (21.49) | 42/449 (9.35) | <0.001 |
| Anti-SSB positivity | 3/121 (2.48) | 3/449 (0.67) | 0.218 |
| C3, mg/dL | 1.01 (0.85–1.15) | 1.02 (0.89–1.17) | 0.198 |
| C4, mg/dL | 0.21 (0.17–0.27) | 0.22 (0.17–0.28) | 0.390 |
| IgA, g/L | 2.20 (1.69–2.84) | 1.99 (1.53–2.54) | 0.026 |
| IgG, g/L | 13.95 (11.70–15.78) | 12.10 (10.33–14.38) | <0.001 |
| IgM, g/L | 1.12 (0.82–1.63) | 1.22 (0.84–1.71) | 0.216 |
| Initial treatment, n (%) | |||
| Glucocorticoids | 99/100 (99.00) | 251/253 (99.21) | 1.000 |
| Other drugs | 11/100 (11.00) | 13/253 (5.14) | 0.049 |
| Therapeutic measures used during follow-up | |||
| Hydroxychloroquine, n (%) | 6/99 (6.06) | 7/253 (2.77) | 0.204 |
| Ciclosporin, n (%) | 7/99 (7.07) | 4/253 (1.58) | 0.014 |
| Tacrolimus, n (%) | 1/99 (1.01) | 1/253 (0.40) | 0.484 |
| Rituximab, n (%) | 3/99 (3.03) | 5/253 (1.98) | 0.691 |
| IVIG, n (%) | 3/99 (3.03) | 4/253 (1.58) | 0.407 |
| Splenectomy, n (%) | 3/121 (2.48) | 3/453 (0.66) | 0.112 |
| Drug-free time | 1.32 (1.01–1.62) | 1.09 (0.94–1.25) | 0.165 |
| Prognosis, n (%) | |||
| Chronic ITP | 58/99 (58.59) | 195/313 (62.30) | 0.508 |
| Resistant to steroids | 16/93 (17.20) | 26/218 (11.93) | 0.212 |
| CTD development | 19/125 (15.20) | 9/461 (1.95) | <0.001 |
Anti-SSA, anti-Sjogren’s syndrome A antibody; anti-SSB, anti-Sjogren’s syndrome B antibody; CTD, connective tissue disease; ENA, extractable nuclear antigen antibodies; ITP, immune thrombocytopaenia; IVIG, intravenous immunoglobulin; PAIgG, platelet-associated IgG.