Characteristics of TNFi-treated patients with psoriatic arthritis at start of follow-up, grouped by country
| Sweden 2006–2019 | Denmark 2006–2016 | Finland 2006–2017 | Norway 2006–2019 | Iceland 2006–2017 | |
| All, n | 6505 | 2429 | 474 | 879 | 334 |
| Male, n (%) | 3158 (48.6) | 1098 (45.2) | 256 (54.0) | 425 (48.7) | 136 (40.7) |
| Age (years), mean (SD) | 49.4 (12.9) | 47.2 (12.3) | 48.3 (11.6) | 47.5 (12.2) | 48.4 (13.2) |
| BMI (kg/m2) | N/A | 27.7 (24.2 to 30.9) | 27.8 (25.1 to 31.2) | N/A | 29.6 (26.1 to 33.1) |
| BMI missing (n, %) | 6505 (100) | 2036 (83.8) | 86 (18.1) | 879 (100) | 206 (61.7) |
| Smoking status, n (%) | |||||
| Current | 295 (4.5) | 296 (12.2) | 12 (2.5) | 176 (20.0) | 33 (9.9) |
| Previous | 833 (12.8) | 240 (9.9) | N/A | 271 (30.8) | 59 (17.7) |
| Never | 915 (14.1) | 487 (20.0) | 88 (18.6) | 299 (34.0) | 98 (29.3) |
| Missing | 4462 (68.6) | 1406 (57.9) | 374 (78.9) | 133 (15.1) | 144 (43.1) |
| Disease-related characteristics at start of first TNFi | |||||
| DAS28-CRP (0–10) | 4.1 (3.3–4.8) | 4.0 (3.0–5.0) | 3.7 (2.5–4.7) | 3.5 (2.7–4.3) | 4.4 (3.9–5) |
| Missing n (%) | 2613 (40.2) | 745 (30.7) | 128 (27.0) | 110 (12.5) | 189 (56.6) |
| CRP (mg/L) | 5 (2–13) | 6 (2–15) | 7 (3–15) | 5 (2–11) | N/A |
| Swollen joint count (0–28) | 2 (0–5) | 2 (0–4) | 1 (0–4) | 1 (0–3) | 4 (2–6) |
| Tender joint count (0–28) | 4 (2–8) | 5 (2–11) | 1 (0–4) | 2 (1–6) | 5 (2–8) |
| HAQ Score (0–3) | 0.9 (0.5–1.3) | 1 (0.6–1.5) | 0.8 (0.4–1.2) | 0.6 (0.3–0.9) | 1.2 (0.6–1.6) |
| Missing n (%) | 2415 (37.1) | 1174 (48.3) | 100 (21.1) | 51 (5.8) | 192 (57.5) |
| First TNFi, n (%) | |||||
| Adalimumab | 1996 (30.7) | 939 (38.7) | 188 (39.7) | 147 (16.7) | 25 (7.5) |
| Certolizumab pegol | 248 (3.8) | 215 (8.9) | 15 (3.2) | 184 (20.9) | 1 (0.3) |
| Etanercept | 2697 (41.5) | 527 (21.7) | 148 (31.2) | 302 (34.4) | 65 (19.5) |
| Golimumab | 450 (6.9) | 217 (8.9) | 38 (7.9) | 142 (16.2) | 42 (12.6) |
| Infliximab | 1114 (17.1) | 531 (21.9) | 85 (17.9) | 104 (11.8) | 199 (59.6) |
| Other antirheumatic treatment, n (%) at start of first TNFi | |||||
| Methotrexate, n (%) | 2726 (41.9) | 1233 (50.8) | 269 (56.8) | 520 (59.2) | 147 (44) |
| Oral steroid, n (%) | 909 (14.0) | 506 (20.8) | 128 (26.7) | 300 (34.1) | 12 (3.6) |
| Calendar year at start of first TNFi, n (%) | |||||
| 2006–2010 | 1536 (23.6) | 1034 (42.6) | 165 (34.8) | 258 (29.4) | 73 (21.9) |
| 2011—end of follow-up | 4969 (76.4) | 1395 (57.4) | 309 (65.2) | 621 (70.6) | 261 (78.1) |
| Comorbidities and extra-articular manifestations, as registered in national patient registers up to 10 years prior to start of first TNFi, n (%) | |||||
| Cardiovascular disease | 360 (5.5) | 167 (6.9) | 33 (6.9) | N/A | N/A |
| COPD | 97 (1.5) | 39 (1.6) | 2 (0.4) | N/A | N/A |
| Diabetes mellitus | 430 (6.6) | 104 (4.3) | 36 (7.6) | N/A | N/A |
| Hypertension | 964 (14.8) | 231 (9.5) | 73 (15.4) | N/A | N/A |
| Inflammatory bowel disease | 120 (1.8) | 44 (1.8) | 14 (2.9) | N/A | N/A |
| Uveitis | 170 (2.6) | 32 (1.3) | 14 (2.9) | N/A | N/A |
| Urethritis | 38 (0.6) | ≤3 | 0 (0) | N/A | N/A |
| Hospitalisations, n, mean (range) | 1 (0–2) | 4 (1–7) | 2 (1–4) | N/A | N/A |
| Hip and/or knee replacement any time prior to start of first TNFi | 286 (4.4) | 72 (3.0) | 48 (10.1) | N/A | N/A |
| Mean time of follow-up in years (SD) | 5.7 (3.8) | 5.1 (2.9) | 6.1 (3.3) | 6.8 (3.5) | 4.9 (3.4) |
| Median time of follow-up in years (Q1–Q3) | 5.2 (2.3–8.7) | 5.1 (2.7–7.4) | 6.2 (3.2–9.0) | 6.6 (3.9–9.6) | 4.2 (1.9–7.2) |
Values are median and IQR if not stated otherwise. Patients who shifted from biological disease-modifying anti-rheumatic drug (bDMARD)-naïve to TNFi-treated appear in both TNFi-treated and bDMARD-naïve groups because all switchers have two baseline records.
BMI, body mass index; COPD, chronic obstructive pulmonary disease; CRP, C reactive protein; DAS28, Disease Activity Score in 28 joints; HAQ, Health Assessment Questionnaire; N/A, not available; Q1, percentile 25; Q3, percentile 75; TNFi, tumour necrosis factor inhibitor; VAS, visual analogue scale.