Characteristics of bDMARD-naïve patients with psoriatic arthritis from clinical rheumatology registers and national patient registers
| bDMARD-naïve patients with PsA from the clinical rheumatology registers (comparator group 1) n=18 387 | bDMARD-naïve patients with PsA from the national patient registers (comparator group 2)* n=27 286 | |||||
| Sweden 2006–2019 | Denmark 2006–2016 | Finland 2006–2017 | Norway 2006–2019 | Sweden 2006–2019 | Denmark 2006–2016 | |
| All, n | 9560 | 6779 | 1621 | 427 | 21 629 | 5657 |
| Male, n (%) | 4708 (49.2) | 2948 (43.5) | 791 (48.8) | 197 (46.2) | 9944 (46.0) | 2420 (42.8) |
| Age (years), mean (SD) | 53.4 (14.1) | 51.1 (13.7) | 50.5 (13.8) | 49.7 (12.7) | 53.6 (14.8) | 52.1 (13.9) |
| BMI (kg/m2) | N/A | 26.9 (24.1–30.5) | 27.7 (24.6–31.5) | N/A | N/A | N/A |
| BMI missing (n, %) | 9560 (100) | 5774 (85.2) | 116 (7.2) | 427 (100) | N/A | N/A |
| Smoking status, n (%) | ||||||
| Current | 425 (4.4) | 834 (12.3) | 252 (15.5) | 122 (28.6) | N/A | N/A |
| Previous | 1301 (13.6) | 746 (11.0) | N/A | 155 (36.3) | N/A | N/A |
| Never | 1279 (13.4) | 1512 (22.3) | 959 (59.2) | 142 (33.3) | N/A | N/A |
| Missing | 6555 (68.6) | 3687 (54.4) | 410 (25.3) | 8 (1.9) | N/A | N/A |
| Disease-related characteristics at start of follow-up | ||||||
| DAS28-CRP (0–10) | 3.3 (2.4–4.2) | 3.0 (2.2–4.1) | 2.5 (1.7–3.5) | 3.9 (3.1–4.5) | N/A | N/A |
| Missing, n (%) | 3416 (35.7) | 2168 (32.0) | 654 (40.3) | 28 (6.6) | ||
| CRP (mg/L) | 5 (2–10) | 5 (2–10) | 4 (2–8) | 5 (3–15) | N/A | N/A |
| Swollen joint count (0–28) | 1 (0–3) | 1 (0–2) | 0 (0–1) | 2 (1–4) | N/A | N/A |
| Tender joint count (0–28) | 2 (0–5) | 2 (0–6) | 0 (0–1) | 4 (1–8) | N/A | N/A |
| HAQ Score (0–3) | 0.6 (0.3–1.0) | 0.6 (0.1–1.0) | 0.8 (0.2–1.1) | 0.5 (0.3–0.9) | N/A | N/A |
| Missing, n (%) | 3079 (32.2) | 1998 (29.5) | 480 (29.6) | 18 (4.2) | ||
| Other antirheumatic treatment, n (%) at start of follow-up | ||||||
| Methotrexate at start of follow-up, n (%) | 5241 (54.8) | 3257 (48.0) | 703 (43.4) | 362 (84.8) | N/A | N/A |
| Oral steroid at start of follow-up, n (%) | 1280 (13.4) | 855 (12.6) | 219 (13.5) | 296 (69.3) | N/A | N/A |
| Calendar year of start of follow-up | ||||||
| 2006–2010 | 1732 (18.1) | 1498 (22.1) | 128 (7.9) | 350 (82.0) | 7552 (34.9) | 2244 (39.7) |
| 2011—end of follow-up | 7828 (81.9) | 5281 (77.9) | 1493 (92.1) | 77 (18.0) | 14 077 (65.0) | 3413 (60.3) |
| Comorbidities and extra-articular manifestations as registered up to 10 years prior to start of follow-up, n (%) | ||||||
| Cardiovascular disease | 729 (7.6) | 525 (7.7) | 117 (7.2) | N/A | 2117 (9.8) | 539 (9.5) |
| COPD | 207 (2.2) | 164 (2.4) | 23 (1.4) | N/A | 573 (2.6) | 184 (3.3) |
| Diabetes mellitus | 687 (7.2) | 370 (5.4) | 132 (8.1) | N/A | 1674 (7.7) | 378 (6.7) |
| Hypertension | 1694 (17.7) | 760 (11.2) | 263 (16.2) | N/A | 3946 (18.2) | 764 (13.5) |
| Inflammatory bowel disease | 121 (1.3) | 96 (1.4) | 21 (1.3) | N/A | 392 (1.8) | 105 (1.9) |
| Uveitis | 175 (1.8) | 51 (0.7) | 31 (1.9) | N/A | 387 (1.8) | 52 (0.9) |
| Urethritis | 54 (0.6) | 7 (0.1) | 0 (0) | N/A | 91 (0.4) | ≤3 |
| Hospitalisations, n, mean (range) | 1 (0–2) | 3 (1–6) | 1 (0–3) | N/A | 1 (0–2) | 3 (1–6) |
| Hip and/or knee replacement any time prior to start of follow-up | 462 (4.8) | 235 (3.5) | 120 (7.4) | N/A | 1007 (4.7) | 142 (2.5) |
| Number of patients censored during time of follow-up due to start of TNFi | 6513 (68.1) | 1268 (18.7) | 177 (10.9) | 31 (7.3) | 4953 (22.9) | 811 (14.3) |
| Mean time of follow-up in years (SD) | 4.1 (3.2) | 3.2 (2.4) | 3.0 (2.2) | 2.4 (1.9) | 5.6 (4.1) | 4.2 (3.0) |
| Median time of follow-up in years (Q1–Q3) | 3.5 (1.1–6.5) | 2.7 (1.4–2.9) | 2.5 (1.2–4.7) | 2.0 (0.8–3.4) | 5.1 ((1.9–8.8) | 3.8 (1.4–6.5) |
*For Finland, Norway and Iceland, this bDMARD-naïve comparator cohort was not available. Values are median and IQR except where stated otherwise. Patients who shifted from bDMARD-naïve to TNFi-treated appear in both TNFi treated and bDMARD-naïve groups, because all switchers have two baseline records.
bDMARD, biological disease-modifying anti-rheumatic drug; 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; TNFi, tumour necrosis factor inhibitor; VAS, visual analogue scale.