Table 3 Cox regression model to assess factors associated with RA duration until drug initiation

Female sex (ref. male sex)

0.93 (0.86; 1.01)

0.099

1.39 (0.97; 1.98)

0.07

0.96 (0.78; 1.19)

0.719

0.9 (0.81; 0.99)

0.026

Age at treatment start

0.98 (0.98, 0.98)

 < 0.001

1.00 (0.99; 1.01)

0.806

0.98 (0.97; 0.98)

 < 0.001

0.98 (0.98; 0.98)

 < 0.001

Seropositivity

0.89 (0.82; 0.98)

0.015

0.74 (0.50; 1.09)

0.124

0.76 (0.61; 0.95)

0.014

0.93 (0.84; 1.04)

0.193

Year of treatment start (ref. < 2007)

 2007–2016

1.37 (1.18; 1.60)

 < 0.001

-

-

-

-

-

-

 > 2016

1.43 (1.23; 1.66)

 < 0.001

-

-

-

-

-

-

Smoking habit (ref. non-smoker)

 Smoker

1.2 (1.10; 1.32)

 < 0.001

1.44 (0.96; 2.14)

0.075

1.29 (1.03; 1.60)

0.024

1.20 (1.08; 1.33)

0.001

 Former smoker

1.11 (1.00; 1.23)

0.053

1.89 (0.98; 3.62)

0.057

1.13 (0.83; 1.54)

0.434

1.11 (0.99; 1.24)

0.07

BMI (ref. Normal weight)

 Overweight

1.07 (0.98; 1.17)

0.119

0.85 (0.53; 1.34)

0.473

1.15 (0.91; 1.46)

0.233

1.06 (0.97; 1.17)

0.212

 Obesity

1.16 (1.05; 1.27)

0.003

0.82 (0.48; 1.39)

0.460

1.23 (0.95; 1.59)

0.11

1.15 (1.04; 1.28)

0.009

Concomitant treatment

 Methotrexate

1.12 (1.04; 1.21)

0.003

1.21 (0.94; 1.55)

0.148

1.17 (0.97; 1.42)

0.11

1.10 (1.01; 1.20)

0.026

 Other csDMARDs

0.94 (0.87; 1.01)

0.095

1.19 (0.91; 1.56)

0.193

1.09 (0.89; 1.33)

0.405

0.89 (0.81; 0.97)

0.01

 Glucocorticoids

1.09 (1.02; 1.17)

0.017

1.06 (0.82; 1.36)

0.648

1.06 (0.89; 1.26)

0.523

1.10 (1.01; 1.19)

0.024