Table 2.
Hazard Ratios for Adult Cardiovascular Events According to Childhood, Adult, or Childhood plus Adult Risk Scores.*
| Variable | Hazard Ratio (95% Ci)† | |
|---|---|---|
| Fatal Event | Fatal or Nonfatal Event | |
| Childhood risk factor | ||
| Youth smoking: yes vs. no | 1.61 (1.21–2.13) | 1.70 (1.49–1.93) |
| z Score for body-mass index | 1.44 (1.33–1.57) | 1.45 (1.38–1.53)‡ |
| z Score for systolic blood pressure | 1.34 (1.19–1.50) | 1.33 (1.24–1.42) |
| z Score for ln(triglycerides) | 1.50 (1.33–1.70) | 1.45 (1.34–1.56) |
| z Score for total cholesterol level | 1.30 (1.14–1.47) | 1.31 (1.22–1.42) |
| Combined-risk z score§ | 2.71 (2.23–3.29) | 2.75 (2.48–3.06)‡ |
| Subgroup with risk factors evaluated in adulthood | ||
| Adult combined-risk z score§ | 3.20 (2.46–4.17) | 2.88 (2.47–3.35)‡ |
| Childhood plus adult combined-risk z scored¶ | ||
| Childhood combined-risk z score | 1.23 (0.83–1.82) | 1.25 (1.03–1.52) |
| Adult combined-risk z score | 2.88 (2.06–4.05) | 2.58 (2.15–3.09) |
| Childhood combined-risk z score plus change in combined-risk z score from childhood to adulthood¶ | ||
| Childhood combined-risk z score | 3.54 (2.57–4.87) | 3.21 (2.69–3.85)‡ |
| Change in combined-risk z score from childhood to adulthood | 2.88 (2.06–4.05) | 2.58 (2.15–3.09) |
All models were adjusted for sex, Black race, cohort, mean age at and calendar year of childhood visits, and parental education level. Hazard ratios and confidence intervals were based on data imputed to represent all 38,589 childhood participants. The imputation was based on 319 fatal cardiovascular events that occurred among 38,589 participants and 779 observed fatal or nonfatal cardiovascular events that occurred among 20,656 participants. The widths of the confidence intervals were not adjusted for multiple comparisons. ln(triglycerides) denotes the triglyceride level transformed by means of the natural logarithm.
Hazard ratios are reported per unit increase in the z score for the risk factor, except for the hazard ratio with respect to youth smoking, which is reported for the comparison of “yes” and “no.”
In the testing of the proportionality assumption, which was performed with the addition of the interaction term between the risk factor and age (transformed by the natural logarithm), the 95% confidence interval excluded 1, which means that the proportional-hazards assumption might have been violated. A separate analysis of early as compared with late events is provided in Section S4 and Table S14 in Supplementary Appendix 1.
Hazard ratios and confidence intervals were based on data imputed to represent all 13,401 participants in whom both childhood and adult risk-factor data were available. The imputation was based on 115 fatal cardiovascular events in 13,401 participants and 406 observed fatal or nonfatal cardiovascular events in 11,156 participants. The combined-risk z score is the mean of the z scores for body-mass index, systolic blood pressure, ln(triglycerides), and total cholesterol, with the youth smoking dichotomous variables coded as 0 z score units for no and 2 z score units for yes. The combined-risk z score was calculated consistently in childhood and adulthood.
These two models are alternate ways of expressing the same information in a regression model through rearrangement of the terms of the model. Algebraically, the adult minus child term in the second model is the same as the adult term in the first, whereas the child term in the second model is the same as the child term plus the adult term in the first (Section S3C).