Rheumatoid factor positivity by consumption of coffee. Odds ratios with 95% confidence intervals (CI) adjusted for age and sex using logistic regression model
| Cups of coffee a day | Number of subjects examined | Sensitised sheep cell agglutination test | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Titre ⩾32 | Titre ⩾64 | Titre ⩾128 | ||||||||||
| Number of cases | Odds ratio | 95% CI | Number of cases | Odds ratio | 95% CI | Number of cases | Odds ratio | 95% CI | ||||
| 0 | 367 | 5 | 1.00 | 3 | 1.00 | 1 | 1.00 | |||||
| 1 | 238 | 4 | 1.22 | 0.32 to 4.58 | 1 | 0.51 | 0.05 to 4.98 | 0 | Indeterminate | |||
| 2 | 623 | 16 | 1.82 | 0.66 to 5.02 | 15 | 2.98 | 0.85 to 10.39 | 10 | 5.84 | 0.74 to 45.98 | ||
| 3 | 698 | 18 | 1.90 | 0.70 to 5.19 | 13 | 2.38 | 0.67 to 8.45 | 7 | 3.80 | 0.46 to 31.09 | ||
| 4 | 1128 | 19 | 1.21 | 0.45 to 3.29 | 10 | 1.10 | 0.30 to 4.05 | 7 | 2.30 | 0.28 to 18.80 | ||
| 5 | 876 | 14 | 1.23 | 0.44 to 3.45 | 11 | 1.67 | 0.46 to 6.02 | 5 | 2.27 | 0.26 to 19.54 | ||
| 6 | 1311 | 34 | 1.96 | 0.76 to 5.05 | 26 | 2.56 | 0.77 to 8.54 | 18 | 5.30 | 0.70 to 39.92 | ||
| 7 | 275 | 3 | 0.85 | 0.20 to 3.60 | 3 | 1.43 | 0.29 to 7.17 | 2 | 2.90 | 0.26 to 32.23 | ||
| 8 | 443 | 10 | 1.82 | 0.62 to 5.39 | 6 | 1.83 | 0.45 to 7.39 | 4 | 3.71 | 0.41 to 33.43 | ||
| 9 | 92 | 2 | 1.64 | 0.31 to 8.61 | 1 | 1.38 | 0.14 to 13.46 | 1 | 4.17 | 0.26 to 67.44 | ||
| 10 | 559 | 12 | 1.75 | 0.61 to 5.01 | 11 | 2.67 | 0.74 to 9.65 | 7 | 5.16 | 0.63 to 42.27 | ||
| ⩾11 | 199 | 9 | 3.82 | 1.26 to 11.63 | 8 | 5.50 | 1.44 to 21.08 | 7 | 14.80 | 1.80 to 121.79 | ||
| p Value for linear trend1-150 | 0.10 | 0.04 | 0.008 | |||||||||
| p Value for departure from linearity1-150 | 0.48 | 0.44 | 0.50 | |||||||||
↵1-150 Likelihood ratio test based on logistic regression model.