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Table 1 Baseline characteristics of patients with RA (cases, n = 2237) and controls (n = 4661) included in the EIRA study between 2005 and 2018, by categories of tea consumption

From: Is tea consumption associated with reduction of risk of rheumatoid arthritis? A Swedish case-control study

  RA cases Controls
Tea, cups/day (median) Non-consumers (0 cups/day) Irregular consumers (< 1 cup/day) Regular consumers (1–2 cups/day) High consumers (≥2 cups/day) Non-consumers (0 cups/day) Irregular consumers (< 1 cup/day) Regular consumers (1–2 cups/day) High consumers (≥2 cups/day)
Tea, median cups/day 0 0.29 1 2 0 0.29 1 2.29
N 955 453 388 441 1941 847 845 1028
Female, n (%) 582 (60.94%) 358 (79.03%) 288 (74.23%) 359 (81.41%) 1255 (64.66%) 643 (75.91%) 622 (73.61%) 817 (79.47%)
Age, mean (std) 56 (13) 51 (15) 56 (15) 55 (14) 55 (14) 51 (14) 56 (13) 54 (14)
Coffee, n (%)         
0 cups/day 70 (7.33) 44 (9.71) 43 (11.08) 100 (22.68) 172 (8.86) 79 (9.33) 83 (9.82) 269 (26.17)
≤2 cups/day 243 (25.45) 181 (39.96) 163 (42.01) 215 (48.75) 529 (27.25) 333 (39.32) 373 (44.14) 459 (44.65)
2–3 cups/day 222 (23.25) 101 (22.30) 85 (21.91) 74 (16.78) 479 (24.68) 211 (24.91) 204 (24.14) 148 (14.40)
> 3 cups/day 420 (43.98) 127 (28.04) 97 (25.00) 52 (11.79) 761 (39.21) 224 (26.45) 185 (21.89) 152 (14.79)
Smoking, n (%)         
Never 290 (30.37) 164 (36.20) 142 (36.60) 213 (48.30) 859 (44.26) 436 (51.48) 433 (51.24) 563 (54.77)
Former 310 (32.46) 160 (35.32) 145 (37.37) 138 (31.29) 564 (29.06) 245 (28.93) 257 (30.41) 262 (25.49)
Current < 20 pack-years 130 (13.61) 48 (10.60) 29 (7.47) 37 (8.39) 173 (8.91) 56 (6.61) 41 (4.85) 55 (5.35)
Current ≥ 20 pack-years 166 (17.38) 41 (9.05) 30 (7.73) 22 (4.99) 198 (10.20) 40 (4.72) 37 (4.38) 44 (4.28)
Education, n (%)         
< 10 years 253 (26.49%) 83 (18.32%) 66 (17.01%) 61 (13.83%) 401 (20.66%) 87 (10.27%) 123 (14.56%) 93 (9.05%)
10–12 years 263 (27.54%) 105 (23.18%) 95 (24,48%) 82 (18.59%) 552 (28.44%) 226 (26.68%) 205 (24.26%) 188 (18.29%)
> 12 years 439 (45.97%) 265 (58.59%) 227 (58.51%) 298 (67.57%) 988 (50.90%) 534 (63.05%) 517 (61.18%) 747(72.67%)
BMI, mean (std) 26.19 (4.55) 25.56 (4.91) 25.46 (4.63) 25.25 (4.39) 25.83 (4.35) 25.18 (4.42) 25.29 (6.76) 25.02 (4.26)
Alcohol intake, mean grams/week (std) 71.62 (101.94) 57.70 (68.60) 57.43 (70.53) 55.68 (92.35) 73.64 (95.06) 75.13 (120.05) 67.20 (75.58) 59.08 (74.42)