Is coronary risk an accurate surrogate for cardiovascular risk for treatment decisions in mild hypertension? A population validation.

Objective To examine the relationship between coronary (CHD) and cardiovascular (CVD) risk in patients with uncomplicated mild hypertension and to determine the accuracy of using CHD risk ≥ 15% over 10 years to identify for antihypertensive treatment those patients with CVD risk ≥ 20% over 10 years as advised in recent British guidelines. Design Comparison of decisions made using CHD risk ≥ 15% over 10 years calculated by the Framingham risk function and estimated using a simple table with CVD risk ≥ 20% over 10 years. Setting British population. Subjects People aged 35-64 years with uncomplicated mild systolic hypertension (SBP 140-159 mmHg, n = 624) from the 1995 Scottish Health Survey. Main outcome measures Relationship between CHD and CVD risk. Sensitivity, specificity, positive and negative predictive values (PPV and NPV). Results CHD risk 15% over 10 years was equivalent to CVD risk 21% over 10 years. Exact CHD risk ≥ 15% over 10 years had sensitivity 79%, specificity 98%, PPV 94% and NPV 93% in detecting CVD risk ≥ 20% over 10 years. Use of the table to estimate CHD risk ≥ 15% over 10 years gave sensitivity 88%, specificity 90%, PPV 76% and NPV 95%. Conclusion CHD risk appears acceptably accurate for targeting treatment in mild hypertension. The risk assessment table, which slightly overestimates CHD risk, was more sensitive in identifying patients with CVD risk ≥ 20% over 10 years and may be preferable to using exact CHD risk. European guidelines which suggest targeting treatment for mild hypertension at CHD risk ≥ 20% over 10 years are over-conservative compared with British guidelines.