Table 1 Characteristics of included cases and controls
From: Abdominal obesity, gender and the risk of rheumatoid arthritis – a nested case–control study
Cases (n = 557) | Controls (n = 1671) | |
|---|---|---|
Female sex, n (%) | 379 (68) | 1137 (68) |
Data from the health examination visit | ||
Age at examination (years), mean (SD) | 51.9 (9.1) | 51.9 (9.1) |
Body mass index (kg/m2), mean (SD) | 26.3 (4.3) | 25.9 (4.0) |
BMI category, n (%) | ||
Underweight | 5 (0.9) | 15 (0.9) |
Normal weight | 220 (39.7) | 748 (45.3) |
Overweight | 231 (41.7) | 661 (40.1) |
Obese | 98 (17.7) | 226 (13.7) |
Smoking habits, n (%) | ||
Non-smoker | 177 (32.2) | 812 (49.6) |
Ex-smoker | 175 (31.9) | 498 (30.4) |
Smoker | 197 (35.9) | 327 (20.0) |
Educational level, n (%) | ||
9 years or less | 219 (39.8) | 538 (32.8) |
10–12 years | 239 (43.5) | 757 (46.1) |
More than 12 years | 92 (16.7) | 346 (21.1) |
Waist circumference (cm), mean (SD) (sample sizea: cases n = 138, controls n = 409) | 92 (14) | 89 (12) |
Abdominal obesityb, n (%) (sample sizea: cases n = 138, controls n = 409) | 54 (39.1) | 131 (32.0) |
Positive ACPA at examination, n (%) (sample sizec: cases n = 476, controls n = 800) | 179 (37.6) | 20 (2.5) |
Data from the time point of RA symptom onset or later (only cases) | ||
Time between the health examination visit and the onset of RA symptom (years) | ||
Mean (SD) | 6.4 (4.5) | |
Median (Q1, Q3) | 5.5 (2.9, 8.9) | |
Age at RA symptom onset (years), mean (SD) | 58.3 (10.5) | |
Positive ACPA at/after RA diagnosis, n (%) (sample sizec: cases n = 473) | 380 (80.4) | |
Positive RF at/after RA diagnosis, n (%) (sample sizec: cases n = 552) | 434 (78.6) | |
Positive ACPA and/or RF at/after RA diagnosis, n (%) (sample sizec: cases n = 554) | 474 (85.6) | |