Why cardiovascular mortality is higher in treated hypertensives versus subjects of the same age, in the general population.

OBJECTIVE

The aim of the present study was to assess whether increased cardiovascular mortality in treated hypertensives could be explained by high blood pressure levels, or by the presence of associated risk factors and/or associated diseases.

DESIGN

The study sample consisted of 8893 treated hypertensive men and women from the Investigations Préventives et Cliniques cohort, and 25880 gender-matched and age-matched untreated subjects from the same cohort. Vital status was obtained for an 8-12 year period.

RESULTS

Treated hypertensive subjects had higher systolic blood pressure (SBP) (+ 15 mmHg) and higher diastolic blood pressure (+ 9 mmHg), and a higher prevalence of associated risk factors and diseases. Treated hypertensives compared with untreated subjects presented a two-fold increase in the risk ratio (RR) for cardiovascular mortality [RR, 1.96; 95% confidence interval (CI), 1.74-2.22] and coronary mortality (RR, 1.99; 95% CI, 1.63-2.44). Adjustment for unmodifiable risk factors decreased the excess cardiovascular risk observed in treated subjects only slightly: RR, 1.77; 95% CI, 1.56-2.00 for cardiovascular mortality; and RR, 1.76; 95% CI, 1.44-2.16 for coronary mortality. After additional adjustment for modifiable associated risk factors, the increased mortality in treated subjects persisted: RR, 1.52; 95% CI, 1.33-1.74 for cardiovascular mortality; and RR, 1.49; 95% CI, 1.19-1.86 for coronary mortality. Only after additional adjustment for SBP were cardiovascular mortality and coronary mortality similar in the two groups of subjects: RR, 1.06; 95% CI, 0.92-1.23; and RR, 1.06; 95% CI, 0.85-1.35, respectively.

CONCLUSIONS

The increased cardiovascular mortality in treated hypertensive subjects as compared with untreated subjects is mainly due to high SBP levels under treatment. This result suggests that the excess risk found in treated hypertensives may be drastically reduced if SBP were brought under control.