2.
Summary of meta-analysis results
| Exposure | Exposure categories | Study design | Pooled RR for lung cancer (95%CI) |
PQ |
I2 (%) |
PEgger's | |||
| Highest (min to max) | Lowest (min to max)a | Case-control studies | Cohorts | ||||||
|
PQ, p value from Q statistics; PEgger's, p value from Egger's test. a Reference category; bStatistically significant. | |||||||||
| Age at menarche (y) | > 14 to 16-24 | < 11 to ≤16 | 13 | 5 | 0.93 (0.79, 1.10) | < 0.001 | 65.2 | 0.889 | |
| Length of menstrual cycle (d) | > 28 to ≥34 | < 26 to ≤30 | 7 | 0 | 0.72 (0.57, 0.90)b | 0.847 | 0 | 0.448 | |
| Number of pregnancies | ≥1 to ≥7 | 0 to 1-2 | 6 | 1 | 1.10 (0.91, 1.34) | 0.239 | 24.9 | 0.689 | |
| Parity | > 2 to ≥7 | 0 to < 3 | 12 | 6 | 0.91 (0.75, 1.10) | 0.008 | 75.8 | 0.409 | |
| Age at first live birth (y) | ≥23 to ≥30 | ≤18 to < 26 | 6 | 5 | 1.03 (0.88, 1.21) | 0.031 | 48.2 | 0.750 | |
| Age at menopause (y) | ≥50 to 55-60 | ≤40 to < 50 | 11 | 5 | 0.91 (0.70, 1.17) | < 0.001 | 75.8 | 0.028* | |
| OC use | Ever | Never | 6 | 5 | 0.97 (0.89, 1.06) | 0.065 | 42.8 | 0.062 | |
| HRT use | Ever | Never | 5 | 5 | 0.99 (0.91, 1.08) | 0.126 | 35.3 | 0.041* | |