Table 7.
Risk equation for CVD incidence incorporating age at quitting, time since quitting & pack-years into smoking status (Model 4)
| Variable | Parameter Estimate | Standard Error | Chi-Square | P value | Hazard Ratio | 95% CI | |
|---|---|---|---|---|---|---|---|
| Sex | 0.66579 | 0.11303 | 34.6954 | <.0001 | 1.946 | 1.559 | 2.429 |
| Sbp | 0.03269 | 0.00315 | 107.7472 | <.0001 | 1.033 | 1.027 | 1.040 |
| Dbp | -0.03884 | 0.00632 | 37.8124 | <.0001 | 0.962 | 0.950 | 0.974 |
| Total/HDL ratio | 0.22400 | 0.03635 | 37.9841 | <.0001 | 1.251 | 1.165 | 1.343 |
| Diabetes | 0.85100 | 0.15482 | 30.2145 | <.0001 | 2.342 | 1.729 | 3.172 |
| Trglycerides | -0.00185 | 0.00061 | 9.1876 | 0.0024 | 0.998 | 0.997 | 0.999 |
| Pack-years | |||||||
| < = 19 | 0.15082 | 0.34314 | 0.1932 | 0.6603 | 1.163 | 0.593 | 2.278 |
| 20-39 | 0.48640 | 0.21593 | 5.0743 | 0.0243 | 1.626 | 1.065 | 2.483 |
| 40+ | 0.81617 | 0.16208 | 25.3579 | <.0001 | 2.262 | 1.646 | 3.108 |
| Time since quitting | |||||||
| < = 5 years & Age at quitting | |||||||
| ≤ 44 | -0.9483 | 0.71256 | 1.7711 | 0.1832 | 0.387 | 0.096 | 1.566 |
| >44 | 1.0505 | 0.18672 | 31.6533 | <.0001 | 2.859 | 1.983 | 4.123 |
| Time since quitting | |||||||
| >5 years & | |||||||
| Age at quitting | |||||||
| ≤ 44 | -0.1047 | 0.1595 | 0.4315 | 0.5113 | 0.901 | 0.659 | 1.231 |
| >44 | 0.5923 | 0.1789 | 10.9580 | 0.0009 | 1.808 | 1.273 | 2.568 |
| Test | Total | Event | Censored | % Censored | |||
| 3751 | 383 | 3368 | 89.79 | ||||
| Chi-Square | DF | P value | |||||
| Likelihood Ratio | 347.7915 | 13 | <.0001 | ||||
| Hosmer Lemeshow | 6.5337 | 9 | 0.6855 | ||||
| Modified HL | 6.1388 | 9 | 0.7259 | ||||
| Estimate | SE | 95% CI | |||||
| C statistic | 0.7680 | 0.0130 | 0.7426, 0.7934 | ||||
Note: The reference categories for sex, diabetes and the smoking variable are female, no diabetes and never smoker respectively.