Table 2. Subgroup analysis of the relationship between hypertension and risk of breast cancer.
| Characteristics | No. of studies | RR (95% CI) | I2 (%) | P-valuea | P-valueb |
|---|---|---|---|---|---|
| Total | 30 | 1.15 (1.08,1.22) | 72.30 | <0.001 | |
| Geographical region | |||||
| America | 14 | 1.18 (1.06,1.31) | 72.80 | <0.001 | 0.84 |
| Europe | 11 | 1.16 (1.05,1.29) | 78.90 | <0.001 | |
| Asia | 5 | 1.07 (0.94,1.22) | 29.40 | 0.23 | |
| Study design | |||||
| Retrospective | 18 | 1.29 (1.14,1.47) | 77.80 | <0.001 | 0.22 |
| Prospective | 12 | 1.07 (1.01,1.14) | 57.30 | 0.01 | |
| Number of breast cancer cases | |||||
| <200 | 9 | 1.20 (0.97,1.47) | 62.90 | 0.01 | 0.98 |
| ≥200 | 20 | 1.15 (1.07,1.25) | 75.40 | <0.001 | |
| Data extracted from Mets studies | |||||
| Yes | 7 | 1.26 (1.08,1.47) | 59.40 | 0.02 | 0.38 |
| No | 23 | 1.12 (1.05,1.20) | 74.50 | <0.001 | |
| Study quality | |||||
| NOS < 7 | 16 | 1.21 (1.10,1.34) | 80.10 | <0.001 | 0.88 |
| NOS ≥ 7 | 14 | 1.09 (1.01,1.17) | 45.30 | 0.03 | |
| Definition of hypertension | |||||
| ≥130/85mmhg | 11 | 1.14 (1.02,1.26) | 54.40 | 0.02 | — |
| ≥140/90mmhg | 3 | 2.18 (1.31,3.65) | 42.40 | 0.18 | |
| ≥160/95mmhg | 3 | 1.09 (0.91,1.31) | 79.70 | 0.01 | |
| Menopausal status | |||||
| Premenopausal | 9 | 0.97 (0.84,1.12) | 29.30 | 0.19 | — |
| Postmenopausal | 13 | 1.20 (1.09,1.31) | 63.20 | 0.001 | |
RR, relative risk; CI, confidence interval; NOS, Newcastle–Ottawa Quality Assessment Scale; P-valuea, p for heterogeneity within each subgroup; P-valueb., p for heterogeneity between subgroups.