Table 3

Predictors for starting biological therapy in respectively the first and second cohort

Cohort 1 (1990–4)Cohort 2 (2000–4)
Total study population (n=407)RA population (n=378)Total study population (n=416)RA population (n=340)
HR (95% CI)HR (95% CI)HR (95% CI)HR (95% CI)
Age at symptom onset0.98 (0.96 to 1.01)0.98 (0.95 to 1.00)0.97 (0.95 to 0.99)0.96 (0.94 to 0.98)
Female gender2.23 (0.91 to 5.47)2.15 (0.87 to 5.27)2.09 (0.97 to 4.51)1.76 (0.81 to 3.81)
Baseline variables:
 Symptom duration (per month)1.04 (0.98 to 1.11)1.04 (0.98 to 1.11)0.97 (0.91 to 1.02)0.96 (0.91 to 1.02)
 RA (1987 criteria)2.52 (1.08 to 5.91)2.02 (0.87 to 4.72)1.51 (0.82 to 2.79)0.99 (0.53 to 1.82)
 No of swollen joints1.00 (0.94 to 1.05)0.98 (0.93 to 1.04)1.06 (1.00 to 1.12)1.04 (0.98 to 1.09)
 No of tender joints0.97 (0.92 to 1.02)0.97 (0.92 to 1.02)1.02 (0.98 to 1.06)1.01 (0.97 to 1.06)
 CRP (mg/L)1.00 (0.99 to 1.01)1.00 (0.99 to 1.01)1.00 (0.99 to 1.01)1.00 (0.99 to 1.01)
 DAS28(3)CRP1.05 (0.79 to 1.41)1.00 (0.74 to 1.33)1.28 (0.99 to 1.66)1.17 (0.90 to 1.52)
 HAQ score1.15 (0.68 to 1.96)1.08 (0.64 to 1.84)1.45 (0.95 to 2.21)1.35 (0.88 to 2.07)
 Positive RF2.78 (1.31 to 5.90)2.62 (1.24 to 5.54)1.32 (0.68 to 2.58)1.09 (0.56 to 2.16)
 Positive ACPA status7.62 (2.46 to 23.58)6.63 (2.17 to 20.22)4.68 (2.23 to 9.78)3.74 (1.76 to 7.92)
 Shared epitope, no of alleles
  01111
  11.32 (0.52 to 3.34)1.22 (0.49 to 3.07)2.44 (1.09 to 5.46)2.15 (0.96 to 4.79)
  23.07 (1.15 to 8.17)2.92 (1.10 to 7.76)3.25 (1.25 to 8.47)2.60 (1.00 to 6.77)
 Smoking status
  Non-smoker1111
  Ex-smoker0.75 (0.32 to 1.79)0.78 (0.33 to 1.85)1.88 (0.83 to 4.22)2.16 (0.96 to 4.90)
  Current smoker1.14 (0.49 to 2.63)1.28 (0.55 to 1.85)3.71 (1.66 to 8.30)3.74 (1.66 to 8.41)
Treatment effect
 DMARD failure due to inefficacy*0.83 (0.11 to 6.10)0.80 (0.11 to 5.86)2.35 (1.05 to 5.27)2.16 (0.96 to 4.85)
  • Patients in cohort 1 were recruited between 1990 and 1994 and patients in cohort 2 were recruited between 2000 and 2004. HR (95% CI) age at symptom onset adjusted for gender and symptom duration; HR (95% CI) gender adjusted for age at symptom onset and symptom duration; HR (95% CI) symptom duration adjusted for age at symptom onset and gender; all other baseline variables adjusted for age at symptom onset, gender and symptom duration.

  • * Unadjusted HR (95% CI).ACPA, anti-citrullinated protein antibody; CRP, C-reactive protein; DAS28(3)CRP, 28-joint disease activity score based on three components including CRP; DMARD, disease-modifying antirheumatic drug; HAQ, health assessment questionnaire; RA, rheumatoid arthritis; RF, rheumatoid factor.