TABLE 3.

Risk class distributions in the derivation and validation samples

Risk Class	Derivation Sample, % (95% CI) (n = 10,354)	Internal Validation Sample, % (95% CI) (n = 5,177)	External Validation Sample, % (95% CI) (n = 221)
Class I, very low risk	19.4 (18.7–20.2)	19.6 (18.5–20.7)	24.4 (18.9–30.7)
Class II, low risk	21.5 (20.7–22.3)	21.2 (20.1–22.4)	27.1 (21.4–33.5)
Class III, intermediate risk	21.7 (20.9–22.5)	22.2 (21.0–23.3)	28.1 (22.2–34.5)
Class IV, high risk	16.4 (15.7–17.1)	15.8 (14.8–16.8)	11.3 (7.5–16.2)
Class V, very high risk	21.0 (20.3–21.8)	21.3 (20.2–22.4)	9.0 (5.6–13.6)

For definition of abbreviation, see Table 2.