Table 1

Demographics and HRs for ACS among new-onset patient with RA identified 1996–2016 in the SRQ register, their full siblings, matched general population subjects and among full siblings of the latter, and stratified by index patient with RA’s serostatus. NB. The sex distribution between the patients with RA and their matched reference individuals differs compared with the siblings of the patients with RA and the siblings of the reference individuals. Therefore, the proportions and incidence of ACS are not directly comparable between these two pairs of cohorts.

Patients with RAFull siblings of the patients with RAMatched reference individuals in the general populationFull siblings of matched reference individuals in the general population
Incident SRQ cohort
N initial830511 89338 88552 067
Excluded due to ACS event before start of study (%)196 (2.4)331 (2.8)793 (2.0)1274 (2.4)
N study810911 56238 09250 793
Mean age (SD)53.5 (14.3)54.1 (14.2)53.1 (14.3)53.3 (14.3)
Women N (%)5738 (70.8)5734 (49.6)27 035 (71)26 760 (52.7)
Median years of follow-up6.5 (8)6.4 (8.2)6.4 (8.1)6.7 (8.2)
ACS events during study2834109111501
Incidence per 1000 person-years4.644.743.183.84
HR (95% CI)*1.46 (1.28 -1.67)1.22 (1.09 -1.38)‡
1.18 (1.06 -1.32)§
Ref
Within-pair analysis†1.19 (1.04–1.37)Ref
RF-positive subset
N initial5481790825 73634 443
Excluded due to ACS event before start of study (%)127 (3.3)219 (2.8)502 (2.0)803 (2.3)
N study5354768925 23433 640
Mean age (SD)53.1 (14)53.8 (13.9)52.8 (14)52.9 (14)
Women N (%)3854 (72)3852 (50.1)18 220 (72.2)17 653 (52.5)
Median months of follow-up6.9 (8.3)6.8 (8.3)7 (8.3)7.2 (8.5)
ACS events during study1952856091026
Incidence per 1000 person-years4.634.743.063.77
HR (95% CI)*1.52
(1.30 -1.79)
1.27
(1.10 -1.46)
Ref
Within-pair analysis†1.21
(1.02–1.44)
Ref
RF-negative subset
N initial2824398513 14917 624
Excluded due to ACS event before start of follow-up (%)69 (2.4)112 (2.8)291 (2.2)471 (2.7)
N study2755387312 85817 153
Mean age (SD)54.2 (14.9)54.9 (14.6)53.7 (14.9)54 (14.8)
Women N (%)1884 (68.4)1882 (48.6)8815 (68.6)9107 (53.1)
Median months of follow-up5.8 (7.4)5.7 (7.6)5.7 (7.3)5.9 (7.6)
ACS events during study88125302475
Incidence per 1000 person-years4.674.743.463.98
HR (95% CI)*1.34 (1.06 - 1.70)1.13 (0.92 - 1.39)Ref
Within-pair analysis†1.14 (0.89–1.46)Ref
  • *Adjusted for sex, age and calendar period of index case’s diagnosis year and compared with the matched reference individuals in the general population.

  • †Adjusted for age, sex and birth cohort.

  • ‡Compared to the matched reference individuals.

  • §Compared to the full siblings of the matched reference individuals.

  • ACS, acute coronary syndrome; RA, rheumatoid arthritis; RF, rheumatoid factor; SRQ, Swedish Rheumatology Quality.