Table 1 Baseline characteristics amongst matched study subjects with and without initiation of reimbursed biologics

Gender

1.00

 Female, n (%)

372 (15.9)

93 (15.9)

 Male, n (%)

1964 (84.1)

491 (84.1)

Age at first NHI-reimbursed biologic initiation (years), mean ± S.D

40.4 ± 12.5

40.2 ± 12.8

0.77

Disease duration (years), mean ± S.D

6.0 ± 3.5

6.1 ± 3.5

0.44

Monthly income (NTD)

0.70

  ≤ 15,840, n (%)

656 (28.1)

176 (30.1)

 15,841–28,800, n (%)

812 (34.8)

204 (34.9)

 28,801–45,800, n (%)

478 (20.5)

115 (19.7)

  ≥ 45,801, n (%)

390 (16.7)

89 (15.2)

Urbanisation

0.01

 Level 1, n (%)

757 (32.4)

158 (27.1)

 Level 2, n (%)

738 (31.6)

181 (31.0)

 Level 3, n (%)

416 (17.8)

109 (18.7)

 Level 4, n (%)

425 (18.2)

136 (23.3)

CCI at the year of index date, mean ± S.D

0.2 ± 0.7

0.4 ± 0.8

 < 0.01

 CCI = 0, n (%)

1994 (85.4)

405 (69.3)

 CCI ≥ 1, n (%)

342 (14.6)

179 (30.7)

 < 0.01

Extra-articular manifestations

 Uveitis, n (%)

59 (2.5)

42 (7.2)

 < 0.01

 Psoriasis, n (%)

10 (0.4)

42 (7.2)

 < 0.01

 Inflammatory bowel disease, n (%)

7 (0.3)

7 (1.2)

0.01

Medications

 NSAIDs, n (%)

1663 (71.2)

579 (99.1)

 < 0.01

 Methotrexate, n (%)

50 (2.1)

124 (21.2)

 < 0.01

 Sulfasalazine, n (%)

656 (28.1)

506 (86.6)

 < 0.01

 Corticosteroids, n (%)

492 (21.1)

292 (50.0)

 < 0.01

 Corticosteroids, prednisolone equivalent dose (mg/day), mean ± S.D

0.2 ± 1.9

1.2 ± 2.8

 < 0.01

Exposed levels of ambient air pollutants

 PM2.5 (per 10 μg/m³), mean ± S.D

3.0 ± 0.6

3.0 ± 0.6

0.38

 PM10 (per 10 μg/m³), mean ± S.D

5.2 ± 1.2

5.2 ± 1.1

0.78

 SO₂ (per 10 ppb), mean ± S.D

0.4 ± 0.1

0.3 ± 0.1

0.01

 NO₂ (per 10 ppb), mean ± S.D

1.9 ± 0.6

1.8 ± 0.5

 < 0.01

 CO (per 1 ppm), mean ± S.D

0.6 ± 0.2

0.5 ± 0.2

0.02

 O₃ (per 10 ppb), mean ± S.D

2.8 ± 0.3

2.8 ± 0.3

0.08