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 onset | 0.98 (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 gender | 2.23 (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 joints | 1.00 (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 joints | 0.97 (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)CRP | 1.05 (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 score | 1.15 (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 RF | 2.78 (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 status | 7.62 (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 | ||||
0 | 1 | 1 | 1 | 1 |
1 | 1.32 (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) |
2 | 3.07 (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-smoker | 1 | 1 | 1 | 1 |
Ex-smoker | 0.75 (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 smoker | 1.14 (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.