Baseline demographic and clinical characteristics for the 4 cohorts within the subsample of patients with inflammatory polyarthritis who were DMARD-naive at baseline.
| Characteristics | Cohort 1, 1990–1994, n = 864 | Cohort 2, 1995–1999, n = 620 | Cohort 3, 2000–2004, n = 340 | Cohort 4, 2005–2008, n = 240 | p | ||||
|---|---|---|---|---|---|---|---|---|---|
| Demographics | |||||||||
| Age at symptom onset, yrs, median [IQR] | 864/864 | 54 [41, 67] | 620/620 | 55 [43, 69] | 340/340 | 57 [43, 70] | 240/240 | 56 [44, 69] | 0.02* |
| Symptom duration, mos, median [IQR] | 864/864 | 5 [3, 9] | 620/620 | 6 [3, 12] | 340/340 | 6 [3, 11] | 240/240 | 5 [3, 9] | < 0.001* |
| Sex, female, % | 568/864 | 65.7 | 409/864 | 66.0 | 223/340 | 65.6 | 160/240 | 66.7 | 0.99 |
| Smoking status, % | |||||||||
| Never | 271/863 | 31.4 | 256/619 | 41.4 | 105/311 | 33.8 | 71/208 | 34.1 | < 0.001* |
| Ex-smoker | 365/863 | 42.3 | 218/619 | 35.2 | 130/311 | 41.8 | 87/208 | 41.8 | 0.04* |
| Current smoker | 227/863 | 26.3 | 145/619 | 23.4 | 76/311 | 24.4 | 50/208 | 24.0 | 0.22 |
| BMI | |||||||||
| Normal, < 25 | NA† | NA† | 133/329 | 40.4 | 71/237 | 30.0 | 0.02* | ||
| Overweight, ≥ 25 and < 30 | 124/329 | 37.7 | 94/237 | 39.6 | 0.51 | ||||
| Obese, ≥ 30 and < 35 | 62/329 | 18.8 | 52/237 | 22.0 | 0.31 | ||||
| Morbidly obese, ≥ 35 | 10/329 | 3.0 | 20/237 | 8.4 | 0.004* | ||||
| Disease characteristics | |||||||||
| DAS28, mean (SD) | 686/864 | 3.88 (1.46) | 501/620 | 3.56 (1.38) | 268/340 | 3.51 (1.25) | 191/240 | 3.79 (1.22) | 0.001* |
| HAQ score, median [IQR] | 854/864 | 0.63 [0.25, 1.38] | 618/620 | 0.63 [0.13, 1.25] | 330/340 | 0.75 [0.25, 1.38] | 239/240 | 0.75 [0.25, 1.38] | 0.12 |
| RF and/or anti-CCP positivity, % | 170/641 | 26.5 | 149/509 | 29.3 | 96/264 | 36.4 | 88/193 | 45.6 | < 0.001* |
| CRP, mg/l, median [IQR] | 686/864 | 4 [0, 14] | 501/864 | 7 [0, 17] | 268/340 | 7 [3, 17] | 191/240 | 12 [7, 21] | < 0.001* |
| Met 2010 RA criteria, % | 488/864 | 56.5 | 283/620 | 45.7 | 150/340 | 44.1 | 100/240 | 55.4 | < 0.001* |
| Medication | |||||||||
| Used steroids prior to assessment, % | 61/864 | 7.1 | 88/620 | 14.2 | 25/340 | 22.1 | 39/240 | 16.3 | < 0.001* |
↵* Statistical significance set at 0.05 level.
↵† NA: Not available because these data were not collected. HAQ: Health Assessment Questionnaire; DAS28: Disease Activity Score; RF: rheumatoid factor; anti-CCP: anticyclic citrullinated peptide antibody; DMARD: disease-modifying antirheumatic drugs; IQR: interquartile range; BMI: body mass index; CRP: C-reactive protein; RA: rheumatoid arthritis.