Table 2 Relative risks (RRs) and 95% confidence intervals (95% CIs) for categories of pack-years of smoking
From: Cigarette smoking and risk of rheumatoid arthritis: a dose-response meta-analysis
Pack-years | RR (95% CI) |
|---|---|
Never smokers | 1.00 |
1 to 10 | 1.26 (1.14 to 1.39) |
11 to 20 | 1.70 (1.44 to 2.01) |
21 to 30 | 1.94 (1.65 to 2.27) |
31 to 40 | 2.02 (1.44 to 2.82) |
>40 | 2.07 (1.15 to 3.73) |