Objective: To examine the excess risks associated with prehypertension and absolute benefit of treatment.
Methods: We conducted a prospective cohort study in 169 871 Chinese adults aged 40 years and older. Data on blood pressure and covariables were obtained at a baseline examination in 1991 and follow-up evaluation was conducted in 1999-2000.
Results: Compared with normotension (<120/80 mmHg), prehypertension (120-139/80-89 mmHg) was significantly associated with an increased relative risk (95% confidence interval) of cardiovascular disease (CVD) incidence 1.34 (1.27, 1.42) and mortality 1.22 (1.15, 1.30), coronary disease incidence 1.32 (1.16, 1.50) and mortality 1.47 (1.23, 1.75), and stroke incidence 1.72 (1.59, 1.86) and mortality 1.67 (1.50, 1.86). The population-attributable risk associated with prehypertension was 10.6 and 7.1% for CVD incidence and mortality, 9.9 and 13.9% for coronary disease incidence and mortality, and 19.9 and 18.7% for stroke incidence and mortality. The optimal 5-year number-needed-to-treat to prevent a CVD event or death was 53 and 185, 17 and 51, and eight and 22 for prehypertension, stage 1 hypertension, and stage 2 hypertension, respectively. The optimal number-needed-to-treat to prevent a CVD event was significantly smaller in prehypertension patients with a history of CVD or diabetes (34 for incidence and 44 for mortality) compared with those without (115 for incidence and 352 for mortality).
Conclusion: Prehypertension was related to an increased risk of CVD. Treatment of prehypertension among patients with a history of CVD or diabetes was as beneficial as treatment of stage 1 hypertensive patients without a history of CVD or diabetes.