Table 2

Characteristics of RA-ILD patients and matched comparisons

Patient characteristics	Matched RA comparisons		RA patients with ILD
Mean age at RA diagnosis (years)	66.2		66.5
Median age at RA diagnosis (years)	67.6		67.9
Mean age at index date* (years)	68.1		68.5
Median age at index date* (years)	70.4		70.7
	n	%	n	%
n	11 722	100.0	679	100.0
Age at index date*
≤64 years	4233	36.1	242	35.6
65–74 years	3790	32.3	209	30.8
≥75 years	3699	31.6	228	33.6
Gender
Female	6593	56.2	372	54.8
Male	5129	43.8	307	45.2
Seropositive (M05)
No	6444	55.0	301	44.3
Yes	5278	45.0	378	55.7
Charlson Comorbidity Index
Low (0)	7268	62.0	274	40.4
Medium (1-2)	3337	28.5	290	42.7
High (3+)	1117	9.5	115	16.9
Ischaemic heart disease
No	10 528	89.8	591	87.0
Yes	1194	10.2	88	13.0
Congestive heart failure
No	11 209	95.6	621	91.5
Yes	513	4.4	58	8.5
Diabetes
No	10 858	92.6	612	90.1
Yes	864	7.4	67	9.9

*Index date: the date when both the RA and ILD diagnosis have been assigned for RA patients with ILD and the matching date for the matched RA cohort.
ILD, interstitial lung disease; RA, rheumatoid arthritis.