Table 2. Discrimination and calibration of Framingham functions (FRS), recalibrated FRS and Health ABC function in women (n = 1212).
| 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) | 73.41 (2.84) | 146 | 0.33766 | 0.33766 | 0.00 (−0.06,0.06) | 1.00 (0.95,1.06) |
| Age2 | −0.00268 | −0.00268 | ||||
| TC, mg/dL‡ | ||||||
| <160 | 78 (6%) | 11 | −0.26138 | −0.26138 | ||
| 160–199 | 364 (30%) | 46 | Referent | Referent | ||
| 200–239 | 496 (41%) | 52 | 0.20771 | 0.20771 | ||
| 240–279 | 217 (18%) | 29 | 0.24385 | 0.24385 | ||
| ≥280 | 57 (5%) | 8 | 0.53513 | 0.53513 | ||
| HDL-C, mg/dL‡ | ||||||
| <35 | 21 (2%) | 2 | 0.84312 | 0.84312 | 0.21 (−0.30,0.71) | 1.23 (0.74 ,2.04) |
| 35–44 | 149 (12%) | 22 | 0.37796 | 0.37796 | ||
| 45–49 | 149 (12%) | 21 | 0.19785 | 0.19785 | 0.14 (−0.39,0.67) | 1.15 (0.68,1.95) |
| 50–59 | 322 (27%) | 41 | Referent | Referent | Referent | Referent |
| ≥60 | 571 (47%) | 60 | −0.42951 | −0.42951 | −0.10 (−0.51,0.30) | 0.90 (0.60,1.35) |
| Blood pressure∥ | ||||||
| Optimal | 266 (22%) | 19 | −0.53363 | −0.53363 | −0.26 (−0.86,0.33) | 0.77 (0.42,1.40) |
| Normal | 259 (21%) | 25 | Referent | Referent | Referent | Referent |
| High normal | 254 (21%) | 38 | −0.06773 | −0.06773 | 0.41 (−0.09,0.92) | 1.51 (0.91,2.51) |
| Stage I hypertension | 296 (24) | 46 | 0.26288 | 0.26288 | 0.45 (−0.02,0.91) | 1.56 (0.98,2.49) |
| Stage II–IV hypertension | 137 (11%) | 18 | 0.46573 | 0.46573 | ||
| Diabetes | 141 (12%) | 27 | 0.59626 | 0.59626 | 0.62 (0.20,1.05) | 1.86 (1.22,2.85) |
| Smoker | ||||||
| Never | 714 (59%) | 83 | Referent | Referent | Referent | Referent |
| Former | 388 (32%) | 48 | ||||
| Current | 110 (9%) | 15 | 0.29246 | 0.29246 | 0.29 (−0.25,0.83) | 1.34 (0.78,2.29) |
| Mean survival function at t = 7.5 years, S0(t) | 0.9717¶ | 0.8898# | 0.8962** | |||
| C-index | 0.577 | 0.577 | 0.598†† | |||
| H-L statistics∥ ∥ | 121.43 (<0.001) | 22.73 (0.007) | 7.96 (0.539) | |||
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. Total cholesterol and age2 were omitted because they were unpredictive in these older women. The proportionality assumption was tested using the Therneau and Grambsch statistics, which is based on the Schoenfeld residuals. The assumption was accepted (p = 0.14).
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) = 0.96246 [2], as: Ŝ0(7.5) = S0(10)0.75 = 0.9717 (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 = 0.564 (p = 0.54 for comparison with Framingham function).