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.