Characteristics of studied patients with PADs
| Characteristic | All N=268 | Arthritis n=44 | No arthritis n=224 | P value |
| Age (years) (IQR) | 47.95 (33.13–61.7) | 50.55 (33.25–61.8) | 47.7 (33.13–61.3) | 0.8448 |
| Sex (male), n (%) | 110 (41) | 17 (38.63) | 93 (41.51) | 0.7412 |
| N. European ethnicity, n (%) | 252 (94.03) | 40 (90.9) | 212 (94.64) | 0.3093 |
| Age at diagnosis of PID (years) (IQR) | 34 (24–46) | 34 (23.25–49.5) | 33.5 (21.25–46) | 0.7598 |
| Age group at diagnosis of PID (years), n (%) | ||||
| 0–4 | 9 (3.4) | 2 (4.54) | 7 (3.13) | 0.6448 |
| 5–17 | 31 (11.6) | 4 (9.09) | 27 (12.05) | 0.7968 |
| 18–29 | 72 (26.9) | 11 (25) | 61 (27.23) | 0.8536 |
| 30–50 | 101 (37.7) | 17 (38.63) | 84 (37.5) | 1.000 |
| > 50 | 55 (20.5) | 10 (22.72) | 45 (20.09) | 0.6858 |
| Diagnosis of PID, n (%) | ||||
| CVID | 216 (80.6) | 37 (84.09) | 179 (79.91) | 0.6772 |
| CID | 6 (2.2) | 1 (2.27) | 5 (2.23) | 1.000 |
| Unclassified antibody deficiency | 13 (4.9) | 3 (6.81) | 10 (4.46) | 0.4537 |
| Agammaglobulinaemia | 4 (1.5) | 0 (0) | 4 (1.79) | 1.000 |
| Isolated IgG-subclass deficiency | 10 (3.7) | 2 (4.54) | 8 (3.57) | 0.6708 |
| SPAD | 1 (0.4) | 1 (2.27) | 0 (0) | 0.1642 |
CID, combined immunodeficiency; CVID, common variable immunodeficiency; PAD, primary antibody deficiency; PID, primary immunodeficiency; SPAD, specific polysaccharide antibody deficiency.