Table 3.

Event rates and hazard ratios between ABC-stroke risk classes for the derivation and the validation cohorts

Risk class	n	Events	Incidence rate a	Hazard ratio
Derivation cohort
Low (<1%)	4170	46	0.56 (0.41, 0.74)	1.00 (ref)
Medium (1–2%)	7154	187	1.37 (1.18, 1.58)	2.45 (1.78, 3.38)
High (>2%)	3377	158	2.63 (2.24, 3.08)	4.67 (3.36, 6.48)
Validation cohort
Low (<1%)	820	16	0.56 (0.32, 0.90)	1.00 (ref)
Medium (1–2%)	448	19	1.29 (0.78, 2.02)	2.34 (1.20, 4.55)
High (>2%)	132	13	3.22 (1.71, 5.50)	5.80 (2.79, 12.1)

^a Per 100 person-years.