Long-term change of blood pressure and risk of major cardiovascular disease in middle-aged and older adults with prehypertension who did not take blood pressure-lowering drugs

Background To examine the natural prognosis of prehypertension (i.e., blood pressure of 120-139/80-89 mm Hg) in terms of change of blood pressure and more importantly development of major cardiovascular disease (CVD) in the absence of antihypertensive medications, which could inform decision-making in the management of prehypertension. Methods Participants from the Health and Retirement Study and the English Longitudinal Study of Ageing who had no major CVD and were prehypertensive at baseline, and had at least two blood pressure measurements during the period when they were not treated with antihypertensive medications, were included. The change of blood pressure level from baseline to the last measurement was categorized into the following three patterns: "remained prehypertensive", "regressed to normotension", and "progressed to hypertension". The rate of each transition pattern was calculated. The CVD risk in each of the three groups of people was estimated by the Kaplan-Meier method. Using those who remained prehypertensive as the reference group, the relative risks for CVD in the other two groups were estimated through multivariable Cox regression analysis, and then based on this result the absolute CVD risk attributable to "progressed to hypertension" was quantified. Results A total of 4625 participants (median age 57 years, interquartile range 53 to 64) with prehypertension at baseline were included. Over a median 8-year period, 48.5% of them remained prehypertensive, 23.4% regressed to normotension, and 28.1% progressed to hypertension. Participants who progressed to hypertension had an average blood pressure of 149/85 mm Hg at the last measurement. In the 3618 participants who had at least two blood pressure measurements before CVD occurred or censored (median follow-up: 10 years), 5.6% of those who remained hypertensive, 4.7% of those who regressed to normotension, and 8.6% of those who progressed to hypertension developed major CVD, respectively. Compared to those who remained prehypertensive (with adjustment for major confounders), those who progressed to hypertension had a 40% higher CVD risk. The 10-year CVD risk attributable to progression from prehypertension to hypertension was 2.1%, accounting for 0.6% of the total prehypertensive population. Conclusions In this study population of middle-aged and older adults with prehypertension, three quarters remained prehypertensive or even regressed to normotensive state over an 8-year period without the aid of antihypertensive medications. The proportion of prehypertensive people who would develop CVD because of progression to hypertension was tiny (0.6%), not to mention the CVD risk that could be reduced by interventions (around one fifth of 0.6%, or 0.12%, with drug treatment). These findings question the worthwhileness of any interventions targeted at people with prehypertension.