Characteristics | Cohort 1, 1990–1994, n = 614 | Cohort 2, 1995–1999, n = 456 | Cohort 3, 2000–2004, n = 347 | Cohort 4, 2005–2008, n = 307 | p | ||||
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Demographics Age at symptom onset, yrs, median [IQR] | 614/614 | 56 [44, 68] | 456/456 | 57 [47, 68] | 347/347 | 59 [49, 69] | 307/307 | 56 [45, 67] | 0.02* |
Symptom duration, mos, median [IQR] | 614/614 | 5 [3, 10] | 456/456 | 6 [4, 12] | 347/347 | 7 [4, 12] | 307/307 | 6 [4, 11] | 0.07 |
Sex, female, % | 404/614 | 65.8 | 314/456 | 68.9 | 238/347 | 68.6 | 211/307 | 68.7 | 0.67 |
Smoking status, % | |||||||||
Never | 182/614 | 29.6 | 163/454 | 35.9 | 93/310 | 30 | 79/275 | 28.7 | 0.01* |
Ex-smoker | 260/614 | 42.4 | 173/454 | 38.1 | 137/310 | 44.2 | 125/275 | 45.5 | 0.52 |
Current smoker | 172/614 | 28 | 118/454 | 26 | 80/310 | 25.8 | 71/275 | 25.8 | 0.26 |
BMI | |||||||||
Normal, < 25 | NA† | NA† | 144/336 | 42.9 | 101/301 | 33.5 | 0.02* | ||
Overweight, ≥ 25 and < 30 | 106/336 | 31.6 | 100/301 | 33.2 | 0.58 | ||||
Obese, ≥ 30 and < 35 | 67/336 | 19.9 | 66/301 | 21.9 | 0.49 | ||||
Morbidly obese, ≥ 35 | 19/336 | 5.6 | 34/301 | 11.3 | 0.01* | ||||
Disease characteristics | |||||||||
DAS28, mean (SD) | 518/614 | 4.69 (1.19) | 403/456 | 4.48 (1.22) | 309/347 | 4.25 (1.12) | 267/307 | 4.41 (1.18) | 0.42 |
HAQ score, median [IQR] | 608/614 | 1.06 [0.50, 1.63] | 453/456 | 1.13 [0.5, 1.63] | 340/347 | 1.13 [0.63, 1.75] | 306/307 | 1.13 [0.63, 1.75] | 0.03* |
RF and/or anti-CCP positivity, % | 208/458 | 45.4 | 214/380 | 56.3 | 181/277 | 65.3 | 171/247 | 69.2 | < 0.001* |
CRP mg/l, median [IQR] | 518/614 | 8 [1, 22] | 403/456 | 11 [4, 23] | 309/347 | 13 [5, 26] | 262/307 | 14 [8, 24] | < 0.001* |
Medication | |||||||||
Used DMARD prior to assessment, % | 126/614 | 20.5 | 173/456 | 37.9 | 197/347 | 56.8 | 174/307 | 56.7 | < 0.001* |
Used methotrexate prior to assessment, % | 9/614 | 1.5 | 85/456 | 18.6 | 131/347 | 37.7 | 119/307 | 38.8 | < 0.001* |
Used steroids prior to assessment, % | 51/614 | 8.3 | 81/456 | 17.7 | 106/347 | 30.5 | 61/307 | 19.9 | < 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; ACR/EULAR: American College of Rheumatology/European League Against Rheumatism; RA: rheumatoid arthritis.