Table 3. Sixteen-year risk of coronary heart disease (CHD) under different levels and durations of exposure to systolic blood pressure (SBP), Framingham Offspring Study (1987–1991 to 2007).
| SBP level and duration* | 16-year risk of CHDa | Population risk ratiob | Population risk differenceb | Cumulative percentage intervened on | Average percentage intervened on |
|---|---|---|---|---|---|
| Low SBP for 16 yrs (<120 mmHg)c | 6.7 (5.5 to 8.1) | 1 | 0 | 85 | 55 |
| Prehypertension (120 to <140 mmHg) for 16 yrs | 8.4 (7.3 to 9.5) | 1.26 (1.11 to 1.41) | 1.7 (0.9 to 2.5) | 95 | 55 |
| Low SBP for 8 yrs followed by stage 1 hypertension (140 to <160 mmHg) for 8 yrs | 8.6 (7.5 to 9.7) | 1.28 (1.12 to 1.49) | 1.9 (0.9 to 2.9) | 100 | 68 |
| Low SBP for 12 yrs followed by stage 2 hypertension (≥160 mmHg) for 4 yrs | 8.6 (7.5 to 10.0) | 1.29 (1.11 to 1.57) | 1.9 (0.8 to 3.3) | 100 | 67 |
| Stage 1 hypertension (140 to <160 mmHg) for 16 yrs | 10.4 (8.9 to 12.1) | 1.55 (1.23 to 1.95) | 3.7 (1.8 to 5.6) | 98 | 73 |
| Low SBP for 8 yrs followed stage 2 hypertension (≥160 mmHg) for 8 yrs | 10.5 (8.7 to 12.5) | 1.57 (1.21 to 2.03) | 3.8 (1.7 to 6.1) | 100 | 75 |
| Stage 2 hypertension (≥160 mmHg) for 16 yrs | 13.7 (10.1 to 17.0) | 2.04 (1.40 to 2.90) | 7.0 (3.1 to 10.9) | 98 | 73 |
* Sorted by ascending CHD risk
a. There were 218 cases of CHD among 2,972 cohort participants after 39,884 person-years of follow-up. The observed risk was 8.5%.
b. In addition to systolic blood pressure levels, we modeled 7 other covariates in the analysis: examination cycle, cigarette smoking (current smoker, and number of cigarettes per day if smoker), alcohol consumption (standard drinks per day), body mass index, diabetes, systolic blood pressure, and lipid lowering medication. All models included lagged values of time-varying covariates plus baseline non-time-varying variables: sex, age, education level, marital status at examination 4, and smoking history at examination 3 of the Framingham Offspring Study.
c. Reference category