Table 3. Subgroup analyses of mtDNA copy number with cancer risk in median.
| Study groups | Studies (n) | OR | 95% CI | P | I2 |
|---|---|---|---|---|---|
| Ancestry | |||||
| Asian | 18 | 1.29 | 0.94 to 1.76 | 0.116 | 89.7% |
| White | 8 | 0.97 | 0.64 to 1.47 | 0.894 | 88.0% |
| Gender | |||||
| Male | 15 | 1.40 | 0.97 to 2.04 | 0.076 | 89.5% |
| Female | 15 | 1.27 | 0.92 to 1.75 | 0.151 | 86.8% |
| Study design | |||||
| Prospective | 21 | 1.15 | 0.94 to 1.39 | 0.169 | 75.8% |
| Retrospective | 17 | 1.02 | 0.67 to 1.55 | 0.917 | 93.2% |
| Control source | |||||
| Population | 35 | 1.14 | 0.92 to 1.41 | 0.240 | 88.8% |
| Hospital | 3 | 0.83 | 0.32 to 2.11 | 0.689 | 85.1% |
| Cancer type | |||||
| Digestive | 11 | 0.86 | 0.59 to 1.25 | 0.432 | 88.3% |
| Urogenital | 6 | 1.05 | 0.74 to 1.49 | 0.782 | 79.9% |
| Lymphoma | 5 | 1.76 | 1.08 to 2.85 | 0.023 | 60.3% |
| Respiratory | 5 | 1.02 | 0.73 to 1.43 | 0.904 | 68.0% |
| Head/neck | 5 | 1.63 | 0.62 to 4.31 | 0.323 | 93.9% |
| Breast | 3 | 1.80 | 0.81 to 4.01 | 0.152 | 92.0% |
| Skeleton | 2 | 0.39 | 0.22 to 0.68 | 0.001 | 66.7% |
Abbreviations: OR, odds ratio; 95% CI, 95% confidence interval.