Table 3.

Frequencies for computing continuous net reclassification index for prediction models

	Year 15 PDAY score with vs. without CAC			Cumulative PDAY score to year 15 with vs. without CAC
	No. of participants with  PM1+  > PM1	No. of participants with  PM1+ < PM1	Continuous NRI components	No. of participants with  PM2+ > PM2	No. of participants with  PM2+ < PM2	Continuous NRI components
No CHD event	590	2292	0.591a	438	2385	0.690
CHD event	41	56	–0.155b	39	55	–0.170

P _M1 represents the predicted probability computed from the model consisting of two variables: year 15 age and year 15 PDAY score without the age component.

P _M1+ represents the predicted probability computed from the model consisting of three variables: year 15 age, the year 15 PDAY score without the age component, and presence of year 15 CAC.

P _M2 represents the predicted probability computed from the model consisting of two variables: year 15 age and cumulative PDAY score to year 15 PDAY score without the age component.

P _M2+ represents the predicted probability computed from the model consisting of three variables: year 15 age and cumulative PDAY score to year 15 PDAY score without the age component and presence of year 15 CAC.

^aNon-event NRI = (2292 − 590)/(2292 + 590) = 0.591.

^bEvent NRI = (41 − 56)/(41 + 56) = –0.155.

PDAY, Pathobiological Determinants of Atherosclerosis in Youth; CAC, coronary artery calcium; CHD, coronary heart disease; NRI, net reclassification index.