Risk factors for aneurysm growth
| No. of Studies | Proportion of Growing Aneurysms per Patient-Year (95% CI) | I2 | P Value | |
|---|---|---|---|---|
| Overall growth rate | 21 | 3.0 (2.0–4.0) | 95 | – |
| Age (yr) | ||||
| 50 or younger | 6 | 0.9 (0.0–24.7) | 93 | <.0001 |
| 50 or older | 3 | 3.8 (1.3–11.5) | 96 | |
| 70 or younger | 5 | 2.4 (0.4–16.3) | 96 | .04 |
| 70 or older | 1 | 2.5 (1.2–5.4) | NA | |
| Population | ||||
| Japanese | 9 | 2.7 (1.5–4.7) | 82 | – |
| Finnish | 1 | 2.4 (1.7–3.3) | NA | – |
| Sex | ||||
| Male | 12 | 1.3 (0.5–3.6) | 90 | <.01 |
| Female | 12 | 3.2 (1.6–6.3) | 95 | |
| Aneurysm location | ||||
| ICA | 13 | 2.5 (1.1–5.5) | 92 | <.01 |
| MCA | 13 | 3.3 (1.4–7.9) | 87 | |
| ACA/AcomA | 13 | 1.8 (0.8–4.2) | 89 | |
| VBA | 12 | 3.6 (1.3–9.9) | 85 | |
| Cavernous carotid artery | 2 | 14.4 (5.1–40.2) | 75 | |
| Anterior vs posterior | ||||
| Anterior | 14 | 2.7 (1.4–5.0) | 95 | <.01 |
| Posterior | 13 | 3.8 (1.5–9.9) | 84 | |
| Multiple aneurysms | ||||
| Yes | 13 | 2.3 (1.1–4.8) | 85 | .80 |
| No | 11 | 3.0 (1.7–5.4) | 86 | |
| Prior SAH | ||||
| Yes | 9 | 2.2 (0.7–6.8) | 92 | .06 |
| No | 8 | 4.7 (1.9–11.6) | 95 | |
| Family history | ||||
| Yes | 7 | 5.0 (1.6–15.1) | 79 | .58 |
| No | 7 | 3.8 (1.5–9.3) | 97 | |
| HTN | ||||
| Yes | 11 | 3.9 (1.9–8.0) | 92 | .88 |
| No | 11 | 4.0 (1.9–8.0) | 93 | |
| Smoking | ||||
| Yes | 12 | 5.5 (3.0–9.9) | 81 | <.01 |
| No | 11 | 3.5 (1.7–7.1) | 94 | |
| Shape | ||||
| Saccular | 4 | 5.2 (2.3–11.8) | 75 | <.01 |
| Lobular | 2 | 15.2 (5.8–40.2) | 0 | |
| Daughter sac | 1 | 16.7 (4.9–56.7) | NA | |
| Fusiform | 1 | 13.7 (6.4–29.5) | NA | |
| Shape | ||||
| Saccular | 4 | 5.2 (2.3–11.8) | 75 | <.01 |
| Nonsaccular | 4 | 14.7 (8.6–25.2) | 0 | |
| Size (mm) | ||||
| <3 | 4 | 4.1 (1.3–12.9) | 88 | <.01 |
| >3 | 15 | 5.2 (2.9–9.3) | 87 | |
| <5 | 9 | 2.3 (1.2–4.2) | 89 | <.01 |
| >5 | 13 | 6.5 (3.6–12.0) | 84 | |
| <7 | 11 | 2.5 (1.5–4.1) | 90 | <.01 |
| >7 | 10 | 9.2 (4.1–20.6) | 84 | |
| <10 | 15 | 2.9 (1.6–5.2) | 96 | <.01 |
| >10 | 10 | 9.7 (4.0–23.8) | 81 | |
| <13 | 15 | 3.0 (1.6–5.3) | 96 | <.01 |
| >13 | 5 | 8.1 (1.8–36.1) | 83 | |
| Study risk of bias | ||||
| High | 15 | 2.9 (1.6–5.6) | 95 | <.01 |
| Medium | 4 | 1.7 (0.4–7.2) | 92 | |
| Low | 2 | 1.7 (0.8–3.4) | 86 |
Note:—AcomA indicates anterior communicating artery; VBA, vertebrobasilar artery; HTN, hypertension; ACA, anterior cerebral artery; NA, not applicable.