Table 1. Baseline Participant Characteristics (Full Analysis Set).
| Characteristics | Therapeutic drug monitoring (n = 198) | Standard therapy (n = 200) |
|---|---|---|
| Age, median (IQR), y | 44 (35-57) | 44 (30-55) |
| Sex, No. (%) | ||
| Women | 110 (56) | 93 (47) |
| Men | 88 (44) | 107 (53) |
| Disease duration, median (IQR), y | 3.5 (0.8-15.0) | 3.8 (0.8-12.3) |
| Diagnosis, No. (%) | ||
| Spondyloarthritis | 59 (30) | 58 (29) |
| Ulcerative colitis | 39 (20) | 41 (21) |
| Rheumatoid arthritis | 38 (19) | 42 (21) |
| Crohn disease | 29 (15) | 28 (14) |
| Psoriatic arthritis | 20 (10) | 22 (11) |
| Psoriasis | 13 (7) | 9 (5) |
| Therapy, No. (%) | ||
| Prior biologic therapy | 47 (24) | 45 (22) |
| Prior use of 1 TNF inhibitora | 30 (15) | 29 (15) |
| Prior use of ≥2 TNF inhibitorsa | 15 (8) | 15 (8) |
| Prior use of other biologic therapyb | 8 (4) | 9 (5) |
| Concomitant immunosuppressive therapyc | 112 (57) | 109 (55) |
| Concomitant use of glucocorticoids | 40 (21) | 31 (16) |
| Erythrocyte sedimentation rate, median (IQR), mm/hd | 13 (6-25) | 14 (6-25) |
| C-reactive protein, median (IQR), mg/Le | 5.0 (2.0-14.0) | 5.0 (1.0-15.0) |
| Patient global assessment of disease activity, mean (SD)f | 59.6 (23.0) | 56.8 (22.3) |
| Physician global assessment of disease activity, mean (SD)f | 46.6 (21.1) | 46.4 (21.6) |
| Disease-specific characteristics | ||
| Spondyloarthritis | ||
| HLA-B27 positive, No./total (%) | 41/53 (77) | 42/55 (76) |
| Bath Ankylosing Spondylitis Disease Activity Index, mean (SD)g | 5.1 (1.7) [n = 59] | 5.3 (1.5) [n = 58] |
| Ankylosing Spondylitis Disease Activity Score, mean (SD)g | 3.1 (1.0) [n = 59] | 3.1 (0.9) [n = 58] |
| Ulcerative colitis: Partial Mayo Score, median (IQR)g | 6 (5-7) [n = 39] | 6 (4-7) [n = 41] |
| Rheumatoid arthritis | ||
| Anti–citrullinated protein antibody positive, No./total (%) | 26/38 (68) | 28/42 (67) |
| Rheumatoid factor positive, No./total (%) | 26/37 (70) | 27/42 (64) |
| Disease Activity Score in 28 Joints, mean (SD)g | 4.6 (1.1) [n = 38] | 4.4 (1.2) [n = 42] |
| Crohn disease: Harvey-Bradshaw Index, median (IQR)g | 8 (6-10) [n = 29] | 8 (5-9.5) [n = 28] |
| Psoriatic arthritis: Disease Activity Score in 28 Joints, mean (SD)g | 4.3 (1.0) [n = 20] | 4.8 (1.3) [n = 22] |
| Psoriasis: Psoriasis Area and Severity Index, mean (SD)g | 10.1 (4.8) [n = 13] | 9.7 (4.1) [n = 9] |
Abbreviations: HLA, human leukocyte antigen; IQR, interquartile range; TNF, tumor necrosis factor.
Prior TNF inhibitor use includes etanercept, adalimumab, certolizumab pegol, golimumab, and infliximab.
Other biologic therapy includes abatacept, rituximab, secukinumab, tocilizumab, ustekinumab, and vedolizumab.
Concomitant immunosuppressive therapy includes methotrexate, leflunomide, sulfasalazine, and azathioprine.
For erythrocyte sedimentation rate, the normal range is 0 to 12 mm/h for men and 0 to 17 mm/h for women.
For C-reactive protein, the normal range is 0 to 4 mg/L.
Global assessment of disease activity range, 0 to 100 on a visual analog scale, with 0 indicating no disease activity and 100 indicating the highest possible disease activity.
See the Box and eTable 3 in Supplement 1 for detailed descriptions of the Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, Partial Mayo Score, Disease Activity Score in 28 Joints, Harvey-Bradshaw Index, and Psoriasis Area and Severity Index.