PHASES (Population, Hypertension, Age, Size of aneurysm, Earlier subarachnoid haemorrhage, Site of aneurysm) is a 0–22 point sum of six predictors:

Predictor	Definition	Points
Population	North American or European (non-Finnish)	0
	Japanese	3
	Finnish	5
Hypertension	History of treated or untreated hypertension	1 if present, otherwise 0
Age	Age ≥70 years	1 if ≥70 years, otherwise 0
Aneurysm size	Maximum diameter <7.0 mm	0
	7.0–9.9 mm	3
	10.0–19.9 mm	6
	≥20.0 mm	10
Earlier SAH	Prior aneurysmal SAH from a different intracranial aneurysm	1 if present, otherwise 0
Site	Internal carotid artery	0
	Middle cerebral artery	2
	Anterior cerebral/anterior communicating, posterior communicating, or posterior circulation	4

The total PHASES score is then linked to the 5-year rupture risks from the original pooled analysis.

PHASES Score