Adjusted* odds ratios and 95% confidence intervals (CIs) of “false positive” rheumatoid factor reactions in titres ≥32 and ≥128
| Sensitised sheep cell agglutination test | |||||||
|---|---|---|---|---|---|---|---|
| Waaler-Rose ≥32 | Waaler-Rose ≥128 | ||||||
| Factor | No of subjects examined | No of cases | Odds ratio | 95% CI | No of cases | Odds ratio | 95% CI |
| *All variables in the table were included in the logistic regression model. | |||||||
| Region | |||||||
| Southwest | 1650 | 29 | 1.00 | 7 | 1.00 | ||
| South | 2320 | 59 | 1.49 | 0.95 to 2.35 | 25 | 2.55 | 1.09 to 5.94 |
| West | 1051 | 22 | 1.17 | 0.67 to 2.05 | 10 | 2.25 | 0.85 to 5.94 |
| East | 1156 | 24 | 1.17 | 0.68 to 2.02 | 16 | 3.22 | 1.32 to 7.88 |
| North | 770 | 14 | 0.99 | 0.52 to 1.90 | 11 | 3.00 | 1.15 to 7.80 |
| Age | |||||||
| 30–44 | 2641 | 44 | 1.00 | 18 | 1.00 | ||
| 45–54 | 1562 | 32 | 1.26 | 0.79 to 1.99 | 20 | 1.96 | 1.03 to 3.73 |
| 55–64 | 1285 | 25 | 1.23 | 0.75 to 2.02 | 12 | 1.60 | 0.76 to 3.36 |
| 65–75 | 1018 | 33 | 2.24 | 1.40 to 3.57 | 12 | 2.36 | 1.11 to 5.01 |
| ≥75 | 441 | 14 | 2.39 | 1.28 to 4.49 | 7 | 4.04 | 1.61 to 10.15 |
| Sex | |||||||
| Men | 3216 | 72 | 1.00 | 37 | 1.00 | ||
| Women | 3731 | 76 | 1.11 | 0.76 to 1.63 | 32 | 1.31 | 0.75 to 2.27 |
| Smoking | |||||||
| Never smoked | 3852 | 67 | 1.00 | 21 | 1.00 | ||
| Quit | 1444 | 37 | 1.61 | 1.02 to 2.56 | 18 | 2.67 | 1.31 to 5.47 |
| Cigars, pipe or | |||||||
| <20 cigarettes/day | 1027 | 32 | 2.00 | 1.25 to 3.19 | 20 | 4.12 | 2.08 to 8.17 |
| ≥20 cigarettes/day | 624 | 12 | 1.25 | 0.63 to 2.48 | 10 | 3.46 | 1.43 to 8.35 |
| Coffee | |||||||
| Per cup per day | 6947 | 148 | 1.05 | 0.99 to 1.12 | 69 | 1.09 | 1.00 to 1.19 |