Table 2

Standardised incidence ratios (SIRs)* and 95% CI of multiple sclerosis (MS) diagnosis in ever and never tumour necrosis factor-α inhibitor (TNFi)-treated arthritis patients compared with the general population

Number of person- yearsEver TNFi treatedNever TNFi treated
53 72359 804
Obs/expSIR (95% CI)Obs/expSIR (95% CI)
All8/5.81.38 (0.69 to 2.77)4/5.00.80 (0.30 to 2.12)
Males 5/1.4 3.48 (1.45 to 8.37 ) 1/0.81.19 (0.17 to 8.47)
 Females3/4.40.69 (0.22 to 2.14)3/4.20.72 (0.23 to 2.22)
RA2/3.00.67 (0.17 to 2.66)2/3.20.64 (0.16 to 2.54)
Males 2/0.4 4.95 (1.24 to 19.8) 0/0.40.00 (–)
 Females0/2.60.00 (–)2/2.80.72 (0.18 to 2.88)
PsA1/0.91.12 (0.16 to 8.00)1/0.71.45 (0.20 to 10.3)
 Males0/0.30.00 (–)1/0.25.75 (0.81 to 40.8)
 Females1/0.61.62 (0.23 to 11.5)0/0.50.00 (–)
AS 4/1.0 3.91 (1.47 to 10.42) 0/0.30.00 (–)
Males 3/0.6 5.32 (1.72 to 16.49) 0/0.10.00 (–)
 Females1/0.52.17 (0.31 to 15.47)0/0.20.00 (–)
Other1/0.81.20 (0.17 to 8.55)1/0.71.39 (0.20 to 9.86)
 Males0/0.20.00 (–)0/0.10.00 (–)
 Females1/0.61.56 (0.22 to 11.1)1/0.61.68 (0.24 to 11.9)
Time from start of TNFi treatmentTime from DANBIO entry
<11/1.30.79 (0.11 to 5.61)2/1.91.04 (0.26 to 4.14)
1–25/2.0 2.46 (1.03 to 5.92) 0/2.10.00 (–)
3–52/1.71.17 (0.29 to 4.67)2/0.92.30 (0.57 to 9.19)
6+0/0.80.00 (–)0/0.10.00 (–)
  • *We calculated the expected number of MS cases by multiplying the number of person-years experienced by the cohort members with the appropriate national MS incidence rates among Danish men and women in 5-year age groups and calendar time periods of observation (national rates from the DMSR). SIRs were calculated as the observed number of MS cases divided by the expected number, and corresponding 95% CIs were calculated assuming a Poisson distribution of the observed number of MS cases.

  • exp: expected numbers; Obs: observed numbers.