Table 2. Results of subgroup analyses.
| Group | No. of study | OR (95% CI) |
Heterogeneity test |
|
|---|---|---|---|---|
| P for Q test | I2, %† | |||
| All | 15 | 1.16 (1.06-1.27) | 0.027 | 45.9 |
| Study type | ||||
| Prospective* | 13 | 1.14 (1.04-1.25) | 0.033 | 46.4 |
| Retrospective** | 2 | 1.42 (1.08-1.85) | 0.564 | 0.0 |
| Geographic region | ||||
| Europe | 6 | 1.12 (1.02-1.23) | 0.298 | 17.9 |
| USA | 6 | 1.08 (1.01-1.16) | 0.152 | 38.1 |
| Asia | 3 | 1.57 (1.25-1.96) | 0.340 | 7.2 |
| Menstrual status | ||||
| Premenopausal | 2 | 1.08 (0.91-1.28) | 0.551 | 0.0 |
| Postmenopausal | 6 | 1.08 (1.00-1.16) | 0.208 | 30.3 |
| BMI (kg/m2) | ||||
| < 25 | 3 | 1.09 (0.96-1.25) | 0.408 | 0.0 |
| ≥ 25 | 4 | 1.41 (0.96-2.07) | 0.003 | 78.1 |
| Markers | ||||
| Hs-CRP | 7 | 1.22 (1.10-1.35) | 0.056 | 51.1 |
| CRP | 8 | 1.08 (1.01-1.15) | 0.211 | 27.2 |
| CRP assay methodology | ||||
| ELISA | 5 | 1.25 (1.05-1.49) | 0.623 | 0.0 |
| Other assay | 10 | 1.14 (1.03-1.27) | 0.011 | 58.0 |
| Case diagnosis method | ||||
| Cancer registry | 6 | 1.13 (1.02-1.26) | 0.280 | 20.3 |
| Pathology reports | 5 | 1.23 (1.11-1.37) | 0.109 | 47.1 |
| Medical records | 3 | 1.04 (0.96-1.12) | 0.091 | 58.4 |
Abbreviation: OR, odds ratio; CI, confidence intervals; BMI, body mass index; Hs-CRP, High-sensitivity C-reactive protein; ELISA, enzyme-linked immunosorbent assay.
*Refers to cohort study and nested case-control study;
**Refers to case-control study;
†I2 is interpreted as the proportion of total variation across studies that are due to heterogeneity rather than chance.