Table 3.

Number of events, person-years of follow-up, number of events per 100 000 person-years and relative risk of lung cancer according to autoantibody status in the EIRA subcohort

	No of events (person years of follow-up; no of events per 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 with smoking as pack-years instead of ever/never
	Positive	Negative
RF (n=2060)	30 (49 440; 60.7)	6 (49 440; 12.1)	2.78 (1.16 to 6.69)	3.01 (1.25 to 7.26)	2.82 (1.17 to 6.82)	2.44 (1.01 to 5.89)	2.16 (0.88–5.28)
ACPA (n=2060)	30 (49 440; 60.7)	6 (49 440; 12.1)	3.13 (1.30 to 7.51)	3.43 (1.42 to 8.25)	3.22 (1.33 to 7.77)	2.88 (1.19 to 6.95)	3.29 (1.26–8.58)
RF and/or ACPA (n=2060)	34 (49 440; 68.8)	2 (49 440; 4.0)	6.38 (1.53 to 26.56)	7.62 (1.83 to 31.83)	7.20 (1.72 to 30.11)	6.29 (1.51 to 26.30)	5.76 (1.37–24.21)
RF and ACPA (positive vs double negative) (n=1608)	26 (38 592; 67.4)	2 (38 592; 5.2)	6.67 (1.58 to 28.08)	7.92 (1.87 to 33.50)	7.08 (1.67 to 29.98)	6.21 (1.47 to 26.33)	5.86 (1.37–25.01)

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) all the above plus smoking (model C) and (5) as model C with pack-years instead of smoking ever versus never.

ACPA, anticitrullinated peptide antibody; COPD, chronic obstructive pulmonary disease; EIRA, Epidemiological Investigation of RA; RF, rheumatoid factor.