Stroke risk in treated hypertension based on home blood pressure: the Ohasama study.

BACKGROUND

Several observational studies have shown that treated hypertensives are characterized as having worse prognosis than nonhypertensives. However, there is little evidence based on home blood pressure (home BP) measurement. We compare the risk of stroke between untreated individuals and those taking antihypertensive medication based on home BP and casual-screening BP (casual BP) in the general population.

METHODS

The study included 1,690 untreated and 700 treated subjects aged >or=35 years. We measured home BP and casual BP at the beginning of the study. The risk of first stroke was examined by using the Cox proportional hazards model.

RESULTS

During 11.9 years of follow-up, we observed 242 first-time stroke cases. Treated subjects had significantly higher risk for stroke than untreated subjects based on home BP (relative hazard (RH) = 1.48) as well as on casual BP (RH = 1.78), adjusted for systolic BP values and characteristics. When subjects were classified into six categories based on BP (optimal, normal, high normal, and grade 1-3 hypertension), RHs in treated hypertensives linearly increased (trend P < 0.01) based on home BP. However, there was no consistent association for casual BP (trend P: not significant) in treated subjects. Stroke risk was linearly increased regardless of the BP information source in untreated subjects (home BP: trend P < 0.01, casual BP: trend P < 0.01).

CONCLUSION

The results suggest a strong association between elevated home BP and increased risk of stroke. Home BP is a better tool to assess stroke risk, especially in treated hypertensives.