Summary of subgroup analysis for the associations of blood circulating vitamin D and the risk of colorectal cancer and adenoma by outcome, sex, the subregion of Asia, blood sample type and range.
| Subgroup analysis | Number of estimates | Random effect The summary OR (95% CI) | Ratio of ORs (95% CI) | I 2 (%)* | P value* |
| Outcome | |||||
| Colorectal adenoma | 4 | 0.67 (0.40 to 1.14) | |||
| Colorectal cancer | 4 | 0.83 (0.66 to 1.06) | 1.11 (0.54 to 2.28) | 59.48 | 0.73 |
| Sex | |||||
| Women | 2 | 0.59 (0.13 to 2.74) | |||
| Men | 3 | 1.13 (0.81 to 1.58) | 1.46 (0.03 to 63.5) | 45.89 | 0.70 |
| Subregion | |||||
| Eastern Asia | 7 | 0.75 (0.57 to 1.00) | |||
| Western Asia | 1 | 0.69 (0.36 to 1.34) | 0.92 (0.28 to 2.99) | 59.79 | 0.87 |
| Blood sample type | |||||
| Serum | 3 | 0.52 (0.34 to 0.80) | |||
| Plasma | 4 | 0.77 (0.59 to 1.00) | 1.49 (0.73 to 3.03) | 22.67 | 0.21 |
| Range | |||||
| ≤15 ng/mL | 4 | 0.93 (0.70 to 1.25) | |||
| >15 ng/mL | 4 | 0.62 (0.47 to 0.83) | 0.65 (0.39 to 1.07) | 28.48 | 0.08 |
*I2 and p value related to subgroup differences.
I2, per cent residual variation due to heterogeneity.