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. 2016 Apr;37(4):615–620. doi: 10.3174/ajnr.A4575

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.