Table 1.
Characteristics of the study population of Swedish patients with incident RA 1995–2018 and matched population referents
| All patients with RA | Subcohort of patients with RA included in EIRA | |||
| Incident RA (n=44 101) |
General population (n=216 495) |
Incident RA (n=2060) |
General population (n=2779) |
|
| Age (years), mean±SD | 61±16 | 61±16 | 53±13 | 54±13 |
| Sex (% male) | 31% | 31% | 29% | 29% |
| Education | ||||
| ≤9 years | 31% | 28% | 23% | 17% |
| 10–12 years | 44% | 42% | 47% | 42% |
| >12 years | 25% | 30% | 30% | 41% |
| Smoking at start of follow-up | ||||
| Never | 35% | 45% | ||
| Ever | 65% (N=1924) | 55% (N=2620) | ||
| Comorbid conditions at RA-diagnosis (start of follow-up)* | ||||
| Chronic obstructive pulmonary disease | 1.7% | 0.8% | 0.3% | 0.6% |
| All respiratory tract diseases | 9.9% | 5.5% | 5.7% | 4.9% |
| Interstitial lung disease | 3.6% | 1.6% | 1.0% | 1.4% |
| Heart failure | 1.3% | 0.7% | 0.3% | 0.3% |
| Ischaemic heart disease | 3.2% | 2.5% | 1.2% | 1.3% |
| Renal failure | 0.7% | 0.4% | 0.3% | 0.1% |
*Information about comorbiditied is presented in online supplemental table 2.
EIRA, Epidemiological Investigation of RA; RA, rheumatoid arthritis.