Table 3

HRs of incident TB according to biological exposure in the biological-naïve and biological-exposed RA populations 2002–2011 overall, stratified by calendar period and follow-up time

	Biological-naïve RA		Biological-exposed RA		HR (95% CI)
	No. of TB cases	Person-years	No. of TB cases	Person-years	HR (95% CI)
Overall	32	223 661	18	48 228	4.4 (2.3 to 8.5)
Calendar period
2002–2006	18	102 845	10	11 126	7.9 (3.3 to 18.9)*
2007–2011	14	120 816	8	37 102	2.4 (0.9 to 6.1)
Follow-up time
<5 years	22	151 929	17	37 948	7.8 (3.7 to 16.4)†
≥5 years	10	71 754	1	10 280	1.2 (0.2 to 6.2)†

HR and 95% CI estimated from Cox proportional hazard models using calendar time as the time scale comparing biological-exposed to biological-naïve adjusted for age, sex, country of birth, education, history of chronic obstructive pulmonary disease (COPD), diabetes and cancer. Exposed person time defined as starting at first exposure to biological until first of death, emigration, TB or 31 December 2011.
*COPD variable removed from model.
†Country of birth collapsed into Nordic versus non-Nordic.
RA, rheumatoid arthritis; TB, tuberculosis.