Table 2 Characteristics of the material and results in studies on exposure to antibiotics and risk of juvenile idiopathic arthritis by Horton et al. [30] and Arvonen et al. [31]

Any antibiotics

2.1 (1.2 to 3.5)

0 .007

1.6 (1.3 to 1.9)

<0.001

Anaerobic antibiotics only^c

1.6 (1.0 to 2.6)

0.040

1.3 (1.04 to 1.7)

0.021

Non-anti-anaerobic only^c

1.6 (1.1 to 2.3)

0.009

1.2 (0.9 to 1.7)

0.216

Both non-anti-anaerobic and anti-anaerobic antibiotics^c

NA

NA

1.4 (1.1 to 1.8)

<0.001

Dose response

yes

yes