Table 2 Study design factors within observational studies and their influence on relative risk of infection associated with glucocorticoid therapy

Study design

   Cohort

33

1.55 (1.35, 1.79)

71.3%

1.00 (referent)

   Case-control

9

1.95 (1.61, 2.36)

79.4%

1.26

Definition of exposure

   Baseline

5

1.46 (0.87, 2.45)

79.7%

1.00 (referent)

   Current (within 3/12)

22

1.70 (1.47, 1.97)

58.9%

1.16

   Recent (within 6/12)

7

1.56 (1.24, 1.96)

79.5%

1.07

   Ever

2

1.80 (1.29, 2.51)

52.5%

1.23

   Unclear

6

2.35 (1.27, 4.36)

36.5%

1.61

Adjusted for age and sex

   No

22

1.32 (0.97, 1.80)

67.6%

1.00 (referent)

   Yes

19

1.78 (1.58, 2.01)

82.3%

1.35

Adjusted for disease severity

   No

24

1.41 (1.14, 1.75)

71.3%

1.00 (referent)

   Adjusted for surrogate

10

1.98 (1.68, 2.34)

78.5%

1.40

   Adjusted for direct measurement

6

1.52 (1.17, 1.97)

77.0%

1.08

Adjusted for disease duration

   No

33

1.63 (1.41, 1.89)

76.8%

1.00(referent)

   Yes

6

1.55 (1.20, 2.01)

83.5%

0.95

Adjusted for comorbidity

   No

22

1.30 (0.97, 1.74)

64.2%

1.00 (referent)

   Yes

17

1.74 (1.55, 1.96)

75.1%

1.34

Adjusted for other RA therapies

   No

22

1.28 (0.98, 1.67)

61.1%

1.00 (referent)

   Yes

18

1.84 (1.62, 2.08)

82.8%

1.44