Table 1.
Baseline characteristics of patients starting etanercept originator or biosimilar as their first biologic therapy (unimputed)
| Baseline characteristics | All patients | Etanercept originator | Etanercept biosimilar |
|---|---|---|---|
| Total, n | 1806 | 1009 | 797 |
| Female, n (%) | 1332 (74) | 734 (73) | 598 (75) |
| Age, years | 59 (51, 67) | 59 (51, 68) | 59 (50, 67) |
| BMI, kg/m2 | 28 (24, 32); N = 1353 | 28 (24, 32); N = 752 | 27 (24, 32); N = 601 |
| Smoking status, n (%) | N = 1650 | N = 927 | N = 723 |
| Current smoker | 309 (19) | 177 (19) | 132 (18) |
| Ex-smoker | 669 (41) | 380 (41) | 289 (40) |
| Never-smoked | 672 (41) | 370 (40) | 302 (42) |
| Ethnicity, n (%) | N = 1282 | N = 773 | N = 509 |
| White | 1211 (94) | 732 (95) | 479 (94) |
| Other | 71 (6) | 41 (5) | 30 (6) |
| Number of previous csDMARDs, n (%) | N = 1795 | N = 1004 | N = 791 |
| 1 | 57 (3) | 29 (3) | 28 (4) |
| 2 | 666 (37) | 366 (36) | 300 (38) |
| ≥3 | 1072 (60) | 609 (61) | 463 (59) |
| Any concurrent csDMARD, n (%) | 1423 (79) | 782 (78) | 641 (80) |
| Current MTX, n (%) | 1077 (60) | 601 (60) | 476 (59) |
| Current steroid treatment, n (%) | 428 (24) | 240 (24) | 188 (24) |
| Comorbiditiesa, n (%) | |||
| None | 693 (38) | 357 (35) | 336 (42) |
| 1 | 567 (31) | 325 (32) | 242 (30) |
| 2 | 354 (20) | 211 (21) | 143 (18) |
| ≥3 | 192 (11) | 116 (12) | 76 (10) |
| Disease duration until registration date, years | 5 (2, 11); N = 1753 | 5 (2, 12); N = 984 | 5 (2, 10); N = 769 |
| Treatment within 2-years of diagnosis, n (%) | 513 (29); N = 1753 | 279 (28); N = 984 | 234 (30); N = 769 |
| DAS28 score | 5.8 (5.3, 6.5); N = 1801 | 6.0 (5.4, 6.7); N = 1007 | 5.6 (5.2, 6.3); N = 794 |
| 28 TJC | 13 (8, 19); N = 1691 | 14 (9, 20); N = 964 | 11 (8, 17); N = 727 |
| 28 SJC | 8 (5, 11); N = 1692 | 8 (5, 12); N = 963 | 7 (4, 10); N = 729 |
| CRP, mg/L | 12 (5, 28); N = 1038 | 12 (5, 30); N = 562 | 11 (5, 26); N = 476 |
| ESR, mm/h | 25 (11, 42); N = 1190 | 26 (12, 44); N = 743 | 24 (9, 38); N = 447 |
| PGA (0–100 mm) | 80 (64, 90); N = 1622 | 80 (65, 90); N = 932 | 80 (60, 90); N = 690 |
| HAQ score (0–3) | 1.6 (1.0, 2.1); N = 1420 | 1.6 (1.0, 2.1); N = 811 | 1.5 (0.8, 2.0); N = 609 |
| Anti-CCP positivity, n (%) | 709 (72); N = 986 | 268 (70); N = 381 | 441 (73); N = 605 |
| RF positivity, n (%) | 948 (64); N = 1482 | 546 (62); N = 874 | 402 (66); N = 608 |
| Joint surgery history, n (%) | 306 (19); N = 1619 | 202 (20); N = 989 | 104 (17); N = 630 |
| Year of registration, n (%) | |||
| 2011 | 2 (<1) | 2 (<1) | 0 |
| 2012 | 139 (8) | 139 (14) | 0 |
| 2013 | 234 (13) | 234 (23) | 0 |
| 2014 | 217 (12) | 217 (22) | 0 |
| 2015 | 164 (9) | 164 (16) | 0 |
| 2016 | 294 (16) | 181 (18) | 113 (14) |
| 2017 | 523 (29) | 69 (7) | 454 (57) |
| 2018 | 217 (12) | 3 (<1) | 214 (27) |
| 2019 | 16 (<1) | 0 | 16 (2) |
| Follow-up in BSRBR-RA since registration, years | 4.0 (2.5, 5.1) | 5.0 (3.4, 6.2) | 2.7 (1.8, 4.0) |
All continuous variables are reported as median (interquartile ranges), unless stated otherwise.
a
Comorbidities include hypertension, angina/myocardial infarction, stroke, epilepsy, asthma/chronic obstructive pulmonary disorder, peptic ulcer, liver disease, renal disease, tuberculosis, demyelination, diabetes, hyperthyroidism, depression and cancer. csDMARD: conventional synthetic DMARD; DAS28: DAS of 28 joints; TJC: tender joint count; SJC: swollen joint count; PGA: patient’s global assessment; anti-CCP: anti-cyclic citrullinated peptide; BSRBR-RA: British Society for Rheumatology Biologics Register for RA.