Table 3. Discrimination and calibration of Framingham functions (FRS), recalibrated FRS and Health ABC function in men (n = 981).
| Participants with Risk Factor, N (%) | CHD events (N) | FRS | Recalibrated FRS | Refit FRS (Health ABC function )* | ||
| Coef† | Coef† | Coef (95% CI) | HR (95% CI) | |||
| Age, y, mean (SD) | 73.613 (2.86) | 205 | 0.04826 | 0.04826 | 0.05 (−0.00,0.10) | 1.05 (1.00,1.10) |
| TC, mg/dL‡ | ||||||
| <160 | 139 (14%) | 23 | −0.65945 | −0.65945 | −0.32 (−0.78,0.14) | 0.73 (0.46,1.15) |
| 160–199 | 451 (46%) | 94 | Referent | Referent | Referent | Referent |
| 200–239 | 303 (31%) | 69 | 0.17692 | 0.17692 | ||
| 240–279 | 70 (7%) | 15 | 0.50539 | 0.50539 | 0.10 (−0.20,0.39) | 1.10 (0.82,1.48) |
| ≥280 | 18 (2%) | 4 | 0.65713 | 0.65713 | ||
| HDL-C, mg/dL‡ | ||||||
| <35 | 140 (14%) | 28 | 0.49744 | 0.49744 | ||
| 35–44 | 295 (30%) | 72 | 0.24310 | 0.24310 | Referent | Referent |
| 45–49 | 160 (16%) | 38 | Referent | Referent | ||
| 50–59 | 204 (21%) | 40 | −0.05107 | −0.05107 | −0.23 (−0.58,0.13) | 0.80 (0.56,1.13) |
| ≥60 | 182 (19%) | 27 | −0.48660 | −0.48660 | −0.60 (−1.02 ,−0.19) | 0.55 (0.36,0.83) |
| Blood pressure∥ | ||||||
| Optimal | 214 (22%) | 27 | −0.00226 | −0.00226 | −0.47 (−0.95,0.02) | 0.63 (0.39,1.02) |
| Normal | 210 (22%) | 42 | Referent | Referent | Referent | Referent |
| High normal | 188 (19%) | 51 | 0.28320 | 0.28320 | ||
| Stage I hypertension | 258 (26%) | 59 | 0.52168 | 0.52168 | 0.18 (−0.16,0.53) | 1.20 (0.85,1.70) |
| Stage II–IV hypertension | 111 (11%) | 26 | 0.61859 | 0.61859 | ||
| Diabetes | 151 (15%) | 38 | 0.42839 | 0.42839 | 0.23 (−0.12,0.58) | 1.26 (0.88,1.79) |
| Smoker | ||||||
| Never | 302 (31%) | 56 | Referent | Referent | Referent | Referent |
| Former | 568 (58%) | 125 | ||||
| Current | 111 (11%) | 24 | 0.52337 | 0.52337 | 0.28 (−0.15,0.71) | 1.32 (0.86,2.03) |
| Mean survival function at t = 7.5 years, S0(t) | 0.9241¶ | 0.7929# | 0.8032** | |||
| C-index | 0.583 | 0.583 | 0.606†† | |||
| H-L statistics∥ ∥ | 16.27 (0.062) | 16.11 (0.065) | 4.89 (0.844) | |||
Abbreviations: FRS: Framingham risk score; CHD: coronary heart disease; coef: coefficient; CI: confidence interval; SD: standard deviation; TC: total cholesterol; HDL-C: high-density lipoprotein cholesterol.
*Some of the Framingham risk factors categories were collapsed to avoid cells with limited numbers of events and /or unpredictive trends. The proportionality assumption was tested using the Therneau and Grambsch statistics, which is based on the Schoenfeld residuals. The assumption was accepted (p = 0.33).
Based on Wilson et al. [2].
Cholesterol categories proposed by the National Cholesterol Education Program [24].
Blood pressure categories: Optimal (Systolic<120, Diastolic>80); Normal (Systolic<130, Diastolic>85); High normal (Systolic<140, Diastolic>90); Stage I (Systolic<160, Diastolic<100); Stage II–IV (Systolic ≥160, Diastolic ≥100) [24].
Estimated from the Framingham adjusted survival rate (survival rate at the mean value of the risk factors) at 10 years: S0(10) = 90015 [2], as: Ŝ0(7.5) = S0(10)0.75 = 0.9241 (exponential model).
Kaplan-Meier survival function at t = 7.5 years on HABC data, similar to reference [24].
**Adjusted survival rate at t = 7.5 years obtained on the HABC cohort as the baseline survival functions of the multivariate Cox model, similar to reference [9].
After bootstrap correction for the optimism (1000 bootstrap samples from the original dataset [20]), c-index = 0.580 (p = 0.90 for comparison with Framingham function).