Table 1.

Incidence rates, crude and adjusted incidence rate ratios, and 95% confidence intervals for bacterial infection in patients treated with infliximab and etanercept compared with MTX, according to time since initiation of TNFα antagonist treatment^*

	Infliximab	Etanercept	MTX
Less than 6 months since initiation
Bacterial infection, no.	16	12	20
Person-time, years	372	602	1,197
Incidence rate/100 person-years	4.30	1.99	1.67
95% confidence interval	2.46–6.98	1.03–3.48	1.02–2.58
Crude incidence rate ratio	2.57	1.19	Referent
95% confidence interval	1.33–4.96	0.58–2.43	–
Adjusted incidence rate ratio†	2.40	1.61	–
95% confidence interval	1.23–4.68	0.75–3.47	–
More than 6 months since initiation
Bacterial infection, no.	10	19	34
Person-time, years	620	1,414	2,195
Incidence rate/100 person-years	1.61	1.34	1.55
95% confidence interval	0.77–2.97	0.81–2.10	1.11–2.22
Crude incidence rate ratio	1.04	0.87	Referent
95% confidence interval	0.51–2.10	0.50–1.55	–
Adjusted incidence rate ratio†	1.14	1.37	–
95% confidence interval	0.55–2.24	0.74–2.53	–

^*MTX = methotrexate; TNFα = tumor necrosis factor α.

^†Adjusted for age and number of physician visits in the 6 months prior to the index date.