Duration of smoking | Statisticc
| COPD | CB | Emphysema |
|---|
Longest vs. shortest | N | 3 | 4 | 2 |
| Â | F | 1.12 (0.63-1.98) | 2.73 (1.52-4.92) | 7.82 (2.00-30.58) |
| Â | R | 1.12 (0.63-1.98) | 2.25 (0.68-7.42) | 7.67 (0.15-390.65) |
| Â | H, PH
| 0.76, NS | 3.60, < 0.05 | 8.31, < 0.01 |
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a Within each study, results are selected in the following order of preference, within each sex, for: smoking status-current, ever; never cigarettes; smoking product-cigarettes (ignoring other products), cigarettes only, any product; overlapping studies-principal, subsidiary; and then for single sex results in preference to combined sex results. Results adjusted for the most potential confounders are selected.
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b The number of sets of RRs available for key value analysis, where base for comparison is never smoked, is 3 for COPD, 4 for CB and 3 for emphysema, and no key value analysis was carried out.
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c n = number of estimates combined, F = fixed-effect meta-analysis RR (95% CI), R = random-effects meta-analysis RR (95% CI), H = heterogeneity chisquared per degree of freedom, PH = probability value for heterogeneity expressed as p < 0.001, p < 0.05, p < 0.1 or NS (p ≥ 0.1).
