Table 1.

Clinical scores determining IA risk of rupture or growth (adapted from Greving et al. [28], Etminan et al. [18], and Backes et al. [1])

	PHASES score [28]	UIAT score [18]	ELAPSS score [1]
Aneurysm	- Size of the aneurysm (< 7.0 mm, 7.0–9.9 mm, 10.0–19.9 mm, ≥ 20.0 mm)	- Maximum diameter (≤ 3.9 mm, 4.0–6.9 mm, 7.0–12.9 mm, 13.0–24.9 mm, ≥ 25.0 mm)	- Size of the aneurysm (1.0–2.9 mm, 3.0–4.9 mm, 5.0–6.9 mm, 7.0–9.9 mm, ≥ 10.0 mm)
	- Site of IA (ICA, MCA, ACA/Pcom/posterior)	- Location (BasA bifurcation, vertebral/basilar artery, AcomA or PcomA)	- Location of the IA (ICA/ACA/Acom, MCA, Pcom/posterior)
		- Morphology (irregularity or lobulation, size ratio > 3 or aspect ratio > 1.6) - IA growth on serial imaging - IA de novo formation on serial imaging - Contralateral steno-occlusive vessel disease	- Shape of the IA (regular or irregular)
Patient	- Age (< or ≥ 70 years)	- Age (< 40 years, 40–60 years, 61–70 years, 71–80 years, > 80 years)	- Age (≤ or > 60 years)
	- Early SAH from another IA (yes/no) - Population (North American, European (other than Finnish), Japanese, Finnish) - Hypertension (yes/no)	- Risk factor incidence (previous SAH from a different IA, familial IA or SAH, Japanese/Finnish/Inuit ethnicity, current cigarette smoking, hypertension, APKD, current drug and/or alcohol abuse)	- Earlier SAH (yes/no) - Population (North American, China, Europe (other than Finland), Japan, Finland)
		- Clinical symptoms related to unruptured IA (cranial nerve deficit, clinical or radiological mass effect, thromboembolic events from the IA, epilepsy) - Reduced quality of life due to fear of rupture - Aneurysm multiplicity - Life expectancy due to chronic and/or malignant diseases (< 5 years, 5–10 years, < 10 years) - Comorbid diseases (neurocognitive disorder, coagulopathies, thrombophilic diseases, psychiatric disorder)
Treatment		- Age-related risk (< 40 years, 40–60 years, 61–70 years, 71–80 years, > 80 years) - Aneurysm size-related risk (< 6.0 mm, 6.0–10.0 mm, 10.1–20.0 mm, > 20.0 mm) - Aneurysm complexity-related risk (high/low) - Intervention-related risk (constant)

ACA anterior cerebral artery, AcomA anterior communicating artery, APKD autosomal-polycystic kidney disease, BasA basilar artery, IA intracranial aneurysm, ICA internal carotid artery, MCA middle cerebral artery, Pcom posterior communicating artery, SAH subarachnoid hemorrhage