Table 3

Age and sex adjusted relative risks (with 95% confidence intervals (CI)) of developing rheumatoid factor (RF) positive rheumatoid arthritis (RA), RF negative RA, and RA in total by consumption of coffee

Cups of coffee a dayNumber of subjects examinedRF positive RARF negative RARA in total
Number of casesRelative risk95% CINumber of casesRelative risk95% CINumber of casesRelative risk95% CI
099611.0011.0021.00
15640Indeterminate35.460.57 to 52.5932.720.45 to 16.29
2143842.750.31 to 24.6032.020.21 to 19.4572.390.50 to 11.52
3164352.840.33 to 24.3510.540.03 to 8.6861.680.34 to 8.35
42994133.870.51 to 29.6451.390.16 to 11.90182.630.61 to 11.33
52383186.820.91 to 51.1351.790.21 to 15.39234.291.01 to 18.21
64157204.240.57 to 31.6591.790.23 to 14.20293.020.72 to 12.67
778344.620.52 to 41.4011.110.07 to 17.8252.860.55 to 14.75
81686126.480.84 to 49.8452.630.31 to 22.53174.551.05 to 19.72
926026.700.61 to 73.9713.150.20 to 50.5834.930.82 to 29.57
101611106.070.78 to 47.3931.830.19 to 17.62133.950.89 to 17.51
⩾114660Indeterminate0Indeterminate0Indeterminate
p Value for trend3-150 0.020.880.04
p Value for departure from linearity3-150 0.020.920.07
  • 3-150 Likelihood ratio test based on Cox model.