Table 2.

Number of events, person-years of follow-up, number of events per 100 000 person-years and relative risk (HRs) of lung cancer in patients with RA versus general population, in all individuals and stratified by smoking status

All patients	No of events (person years of follow-up; no of events/100 000 person-years)		Crude HR (95% CI)	Model A HR* (95% CI)	Model B HR** (95% CI)	Model C HR** (95% CI)	Model D HR** (95% CI)
	Patients with RA	General population controls
All (NPR, SRQ and EIRA)	590 (1 058 424; 55.7)	1691 (5 195 880; 32.5)	1.76 (1.60 to 1.93)	1.74 (1.58 to 1.91)	1.70 (1.54 to 1.87)

	Patients with RA	EIRA population controls
EIRA cohort, all	36 (49 440; 72.8)	26 (66 696; 38.9)	1.72 (1.04 to 2.86)*	1.92 (1.15 to 3.20)*	1.94 (1.16 to 3.24)*	1.77 (1.06 to 2.97)*	1.99 (1.16 to3.41)*
EIRA, ever smokers	34 (49 440; 68.8)	21 (66 696; 31.5)	1.72 (1.01 to 2.96)†	1.83 (1.06 to 3.18)†	1.82 (1.06 to 3.17)†	N/A	N/A
EIRA, never smokers	2 (49 440; 4.0)	4 (66 696; 6.0)	0.84 (0.15 to 4.58)‡	1.23 (0.22 to 6.76)‡	1.40 (0.25 to 7.77)‡	N/A	N/A

Five HRs are presented: (1) crude; (2) adjusted for age, sex, index year, county of residency (model A); (3) age, sex, index year, county of residency and comorbidities (renal failure, heart failure, ischaemic heart disease, COPD, respiratory infections, hospitalisation) (model B) (4) as model B plus smoking (ever/never) (model C) and (5) as model C with pack-years instead of smoking ever vs never (model D).

*RA versus Gen population.

†Ever smokers with RA versus ever smokers in general population.

‡Never smokers with RA versus never smokers in general population.

COPD, chronic obstructive pulmonary disease; EIRA, Epidemiological Investigation of RA; N/A, not available; NPR, National Patient Register; NPR, National Patient Register; RA, rheumatoid arthritis; SRQ, Swedish Rheumatology Quality.