Response to Is Vascular Morning Blood Pressure Surge in the Elderly Resistant to Antihypertensives and More Risky?

We thank Dr Kario¹ for his interest in our study. Because the age of patients was lower in our study than in the Jichi Medical University Study, we made additional analyses to explore the association between the morning surge in blood pressure (BP) and age in our patients, as well as the potential interaction between age and the morning surge in BP on outcome. Surprisingly, the sleep-trough systolic BP surge did not show any association with age (r=0.01; P=0.59), whereas the preawakening systolic BP surge showed a weak, albeit significant, inverse association with age (r=−0.14; P<0.01). This latter finding could reflect the inverse association between age and the drop in BP from day to night (r=−0.18; P<0.001). More important, the risk of major cardiovascular events progressively declined with higher levels of morning BP surge at any age. The Figure shows the hazard ratio for cardiovascular events at different ages after adjustment for sex, diabetes mellitus, cigarette smoking, serum cholesterol, left ventricular hypertrophy, estimated glomerular filtration rate, and average 24-hour systolic BP. There was no evidence of interaction between age and the systolic BP surge (P=0.43 for the sleep-trough BP surge; P=0.33 for preawakening BP surge).

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Figure.

Prognostic impact of morning blood pressure surge: lack of significant interaction with age.

We concur with Dr Kario¹ that our patients showed lower values of morning BP surge than his patients. Hence, the possibility remains that the adverse impact of BP surge be confined to patients with an extremely high BP rise in the early morning.

Coming to the impact of antihypertensive treatment during follow-up on the prognostic value of the morning surge in BP, our findings are consistent with those of Israel et al,² who found an inverse relation between the morning surge in BP and mortality in a predominantly treated (59%) hypertensive population. In our study, 75.5% of patients were treated with antihypertensive drugs at the last follow-up contact before terminating event or censoring. However, antihypertensive treatment was not a significant predictor of outcome.

In conclusion, the night-morning BP rise and the day-night BP drop are associated biological measures,^2,3 and their prognostic impact looks largely parallel. Future studies should address the prognostic impact of absolute BP levels achieved in the early morning, beyond that of the changes from night to day.

• © 2012 American Heart Association, Inc.