Measuring association between an ordinal variable and presence or absence of an event

Hi everyone,
I have done a research project measuring the severity of tortuosity of iliac arteries in patients who underwent EVAR (Endo Vascular Aneurysm Repair), graded it into None, mild , moderate and severe. i am trying to assess the association between severity of tortuosity and adverse outcomes , what test can i use to measure the association and significance of this association.