Observation group: risk for rupture associated with size, history of SAH, multiplicity, sex, and location of UIA
| Variable | No. Ruptured Aneurysms | No. Total UIAs | Annual Rupture Rate (%) | Hazard Ratio (95% CI) | P Value |
|---|---|---|---|---|---|
| Size of aneurysm (mm) | |||||
| Total | 26 | 741 | 1.8 | ||
| Small (<5 mm) | 7 | 534 | 0.7 | 1 (reference) | |
| Medium (5–9.9 mm) | 10 | 175 | 2.7 | 3.4 (1.3–9.0) | .014 |
| Large (10–24.9 mm) | 7 | 30 | 8.1 | 10.8 (3.7–32.0) | <.001 |
| Giant (> 25 mm) | 2 | 2 | 52.9 | 62.6 (12.7–308.9) | <.001 |
| Location of aneurysm | |||||
| Internal carotid artery | 9 | 319 | 1.6 | 1 (reference) | |
| Anterior cerebral artery | 3 | 136 | 1.2 | 0.8 (0.2–3.2) | .759 |
| Middle cerebral artery | 7 | 213 | 1.7 | 1.1 (0.5–3.7) | .827 |
| Vertebrobasilar artery | 7 | 73 | 3.8 | 2.3 (1.0–6.2) | .104 |
| Circulation location | |||||
| Anterior circulation | 19 | 668 | 1.6 | 1 (reference) | |
| Posterior circulation | 7 | 73 | 3.8 | 2.3 (0.9–5.7) | .068 |
| History of SAH | |||||
| No | 19 | 711 | 2.0 | 1 (reference) | |
| Yes | 7 | 30 | 9.6 | 6.1 (2.5–15.0) | <.001 |
| Small (<5 mm) | 3 | 23 | 5.2 | ||
| Medium (5–9.9 mm) | 2 | 5 | 14.1 | ||
| Large (10–24.9 mm) | 2 | 2 | 166.7 | ||
| Multiplicity of aneurysm | |||||
| Single | 12 | 432 | 1.5 | 1 (reference) | |
| Multiple | 14 | 309 | 2.2 | 1.6 (0.7–3.5) | .254 |
Note:—CI indicates confidence interval.