Baseline demographic and clinical characteristics for the 4 cohorts within the total sample of patients with inflammatory polyarthritis.
| Characteristics | Cohort 1, 1990–1994, n = 1022 | Cohort 2, 1995–1999, n = 883 | Cohort 3, 2000–2004, n = 631 | Cohort 4, 2005–2008, n = 509 | p | ||||
|---|---|---|---|---|---|---|---|---|---|
| Demographics | |||||||||
| Age at symptom onset, yrs, median [IQR] | 1022/1022 | 54 [41, 67] | 883/883 | 55 [44, 67] | 631/631 | 58 [47, 70] | 509/509 | 57 [45, 68] | < 0.001* |
| Symptom duration, mos, median [IQR] | 1022/1022 | 5 [3, 9] | 883/883 | 6 [4, 12] | 631/631 | 6 [4, 11] | 509/509 | 6 [4, 11] | < 0.001* |
| Sex, female, % | 662/1022 | 64.8 | 573/883 | 64.9 | 408/631 | 64.7 | 321/509 | 63.1 | 0.91 |
| Smoking status, % | |||||||||
| Never | 323/1021 | 31.6 | 343/881 | 38.9 | 181/569 | 31.8 | 134/446 | 30.0 | < 0.001* |
| Ex-smoker | 424/1021 | 41.5 | 325/881 | 36.9 | 245/569 | 43.1 | 200/446 | 44.8 | 0.221 |
| Current smoker | 274/1021 | 26.8 | 213/881 | 24.2 | 143/569 | 25.1 | 112/446 | 25.1 | 0.118 |
| BMI | |||||||||
| Normal, < 25 | NA† | NA† | 257/615 | 41.8 | 160/501 | 31.9 | 0.001* | ||
| Overweight, ≥ 25 and < 30 | 224/615 | 36.4 | 192/501 | 38.3 | 0.44 | ||||
| Obese, ≥ 30 and < 35 | 106/615 | 17.2 | 99/501 | 19.8 | 0.25 | ||||
| Morbidly obese, ≥ 35 | 28/615 | 4.6 | 50/501 | 10.0 | < 0.001* | ||||
| Disease characteristics | |||||||||
| DAS28, mean (SD) | 817/1022 | 3.99 (1.45) | 739/881 | 3.68 (1.40) | 521/631 | 3.63 (1.27) | 413/509 | 3.88 (1.26) | < 0.001* |
| HAQ score, median [IQR] | 1010/1022 | 0.75 [0.25,1.37] | 877/883 | 0.75 [0.25,1.37] | 616/631 | 0.80 [0.38, 1.60] | 507/509 | 0.88 [0.38,1.00] | 0.003* |
| RF and/or anti-CCP positivity, % | 234/754 | 31.0 | 251/730 | 34.4 | 225/493 | 45.6 | 202/407 | 49.6 | < 0.001* |
| CRP, mg/l, median [IQR] | 817/1022 | 5 [0, 16] | 739/883 | 8 [0, 19] | 521/631 | 9 [3, 22] | 414/509 | 12 [7, 21] | < 0.001* |
| Met 2010 RA criteria, % | 614/1022 | 60.1 | 456/883 | 51.6 | 347/631 | 55.0 | 307/509 | 60.3 | < 0.001* |
| Medication | |||||||||
| Used DMARD prior to assessment, % | 158/1022 | 15.5 | 263/883 | 29.8 | 291/631 | 46.1 | 269/509 | 52.9 | < 0.001* |
| Used methotrexate prior to assessment, % | 13/1022 | 1.23 | 127/883 | 14.4 | 189/631 | 30.0 | 180/509 | 35.4 | < 0.001* |
| Used steroids prior to assessment, % | 80/1022 | 7.8 | 145/883 | 16.4 | 176/631 | 27.9 | 113/509 | 22.2 | < 0.001* |
↵* Statistical significance set at 0.05.
↵† 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; BMI: body mass index; CRP: C-reactive protein; IQR: interquartile range; RA: rheumatoid arthritis.