Table 3 Association between initiation of reimbursed biologics and air pollutants in adjustment for potential confounders

Age at first NHI-reimbursed biologic initiation

1.00 (0.99–1.01)

0.76

1.00 (0.99–1.01)

0.74

1.00 (0.99–1.01)

0.77

1.00 (0.99–1.01)

0.82

Disease duration

3.22 (2.42–4.27)

 < 0.01

8.95 (5.97–13.42)

 < 0.01

9.25 (6.18–13.86)

 < 0.01

9.19 (6.14–13.77)

 < 0.01

Monthly income (NTD)

  ≤ 15,840

1 (Reference)

1 (Reference)

1 (Reference)

1 (Reference)

 15,841–28,800

0.94 (0.75–1.17)

0.56

0.79 (0.59–1.07)

0.13

0.81 (0.60–1.09)

0.16

0.80 (0.59–1.08)

0.14

 28,801–45,800

0.89 (0.69–1.16)

0.40

0.80 (0.57–1.14)

0.22

0.78 (0.55–1.10)

0.16

0.79 (0.56–1.11)

0.17

  ≥ 45,801

0.85 (0.63–1.13)

0.25

0.70 (0.48–1.02)

0.07

0.69 (0.47–0.99)

0.05

0.69 (0.47–0.99)

0.05

Urbanisation

 Level 1

1 (Reference)

1 (Reference)

1 (Reference)

1 (Reference)

 Level 2

1.17 (0.93–1.49)

0.18

0.97 (0.66–1.42)

0.86

1.14 (0.78–1.65)

0.50

0.94 (0.64–1.38)

0.76

 Level 3

1.25 (0.96–1.65)

0.10

1.13 (0.73–1.73)

0.59

1.27 (0.83–1.94)

0.27

1.10 (0.72–1.68)

0.68

 Level 4

1.53 (1.18–1.98)

 < 0.01

0.78 (0.48–1.28)

0.33

1.14 (0.73–1.78)

0.57

0.86 (0.53–1.40)

0.55

CCI at the year of index date

1.36 (1.22–1.53)

 < 0.01

1.31 (1.12–1.53)

 < 0.01

1.32 (1.13–1.55)

 < 0.01

1.32 (1.13–1.54)

 < 0.01

Extra-articular manifestations

 Uveitis

3.00 (2.00–4.51)

 < 0.01

1.53 (0.93–2.53)

0.09

1.48 (0.90–2.43)

0.13

1.49 (0.90–2.45)

0.12

 Psoriasis

18.25 (9.08–36.66)

 < 0.01

25.19 (9.52–66.61)

 < 0.01

24.27 (9.25–63.69)

 < 0.01

25.83 (9.74–68.53)

 < 0.01

Medications

 NSAIDs

18.19 (14.01–23.62)

 < 0.01

23.66 (8.96–62.49)

 < 0.01

24.56 (9.28–65.03)

 < 0.01

24.87 (9.36–66.06)

 < 0.01

 Methotrexate

12.90 (9.09–18.31)

 < 0.01

4.50 (2.91–6.95)

 < 0.01

4.42 (2.87–6.82)

 < 0.01

4.42 (2.86–6.82)

 < 0.01

 Sulfasalazine

20.00 (13.46–29.71)

 < 0.01

12.16 (8.98–16.46)

 < 0.01

11.68 (8.66–15.76)

 < 0.01

11.78 (8.73–15.90)

 < 0.01

 Corticosteroids, prednisolone equivalent dose (mg/day)

1.35 (1.26–1.46)

 < 0.01

1.12 (1.06–1.18)

 < 0.01

1.11 (1.05–1.18)

 < 0.01

1.11 (1.05–1.18)

 < 0.01

Exposed levels of ambient air pollutants

 PM2.5 (per 10 μg/m³)

0.94 (0.81–1.08)

0.37

0.88 (0.54–1.44)

0.61

0.74 (0.46–1.19)

0.21

0.77 (0.47–1.24)

0.28

 PM10 (per 10 μg/m³)

0.99 (0.92–1.07)

0.78

1.07 (0.81–1.42)

0.61

1.16 (0.89–1.52)

0.28

1.15 (0.88–1.51)

0.30

 SO₂ (per 10 ppb)

0.32 (0.13–0.77)

0.01

0.80 (0.18–3.57)

0.78

0.23 (0.06–0.89)

0.03

0.38 (0.09–1.54)

0.18

 NO₂ (per 10 ppb)

0.73 (0.62–0.87)

 < 0.01

0.23 (0.11–0.50)

 < 0.01

0.59 (0.37–0.94)

0.03

 CO (per 1 ppm)

0.62 (0.40–0.95)

0.03

8.57 (2.02–36.32)

 < 0.01

0.93 (0.41–2.10)

0.86

 O₃ (per 10 ppb)

1.34 (0.96–1.87)

0.08

0.51 (0.24–1.09)

0.08

1.03 (0.53–1.99)

0.93

0.60 (0.28–1.29)

0.19

Akaike information criterion

1675

1687

1682

Coefficient of determination

0.32

0.32

0.32