Table 2

Incidence of any first joint surgery during 5 years of follow-up in each calendar period and calculated incidence rate ratios

Calendar periodJoint surgeries (n)Person-years (pyrs)Incidence rate per 1000 pyrs (95% CI)*Incidence rate ratio (95% CI) within each cohort using the first calendar cohorts as referencesIncidence rate ratio (95% CI) comparing PsA with GPC in each calendar period
PsAGPCPsAGPCPsAGPCPsAGPCPsAGPC
1996–2000145536796674 09218.2
(15.4 to 21.4)
7.2
(6.6 to 7.9)
RefRef2.4
(2.0 to 2.9)
Ref
2001–2004160643757370 85021.1
(18.0 to 24.7)
9.1
(8.4 to 9.8)
1.2
(0.9 to 1.5)
1.3
(1.1 to 1.4)
2.3
(1.9 to 2.7)
Ref
2005–2008264126112 128115 19821.7
(19.2 to 24.6)
11.0
(10.4 to 11.6)
1.2
(1.0 to 1.5)
1.5
(1.4 to 1.7)
2.0
(1.7 to 2.3)
Ref
2009–2012316153614 921143 52421.1
(18.9 to 23.7)
10.7
(10.2 to 11.3)
1.2
(1.0 to 1.4)
1.5
(1.3 to 1.6)
2.0
(1.7 to 2.2)
Ref
  • *Age and sex adjusted incidence rates.

  • GPC, general population cohort; PsA, psoriatic arthritis.