Table 2. Stratified pooled odds ratio (OR) and 95% confidence intervals (CIs) for the correlation between night work shift and risk of colorectal cancer.
| Subgroup | Number of studies | OR (95% CI) | Heterogeneity | P for interaction | |
|---|---|---|---|---|---|
| P | I2 (%) | ||||
| Type of Cancer | |||||
| Colon cancer | 4 | 1.281 (0.949–1.733) | 0.004 | 74.4 | 0.005 |
| Rectal cancer | 4 | 1.318(0.814–2.064) | 0.003 | 74.7 | |
| Study design | |||||
| Cohort | 3 | 1.318 (0.957–1.219) | 0.138 | 38.2 | 0.002 |
| Case-control | 3 | 1.630 (1.324–2.007) | 0.067 | 58.2 | |
| Gender | |||||
| Male | 2 | 1.328 (1.039–1.697) | 0.000 | 87.8 | 0.010 |
| Female | 4 | 1.303 (1.100–1.544) | 0.318 | 14.9 | |
| Region | |||||
| Europe | 3 | 1.120 (0.959–1.307) | 0.021 | 59.6 | 0.006 |
| America | 3 | 1.610 (1.293–2.006) | 0.064 | 58.7 | |
| Exposure assessment | |||||
| Questionnaire | 1 | 1.440 (1.100–1.890) | - | - | 0.002 |
| Interview | 4 | 1.290 (1.073–1.551) | 0.000 | 82.7 | |
| Database | 1 | 1.491 (0.854–2.604) | 0.000 | 77.7 | |
| Control factors | |||||
| >3 | 5 | 1.248 (1.058–1.472) | 0.537 | 0.0 | 0.002 |
| ≤3 | 2 | 1.861 (1.342–2.581) | 0.000 | 79.9 | |
| Study quality | |||||
| High | 4 | 1.274 (1.065–1.523) | 0.848 | 0.0 | 0.004 |
| Low | 2 | 1.533 (1.237–1.899) | 0.000 | 80.9 | |