Morning blood pressure (BP) surge is widely believed to increase cardiovascular disease risk, but a new study suggests that an increase in morning BP over nocturnal levels may represent a healthier form of circadian variation and may not have an adverse predictive nature but rather a favorable one when it comes to all-cause mortality.

Sara Israel, MD, of Hadassah-Hebrew University Medical Center in Jerusalem, Israel, and her colleagues looked at a cohort of 2,627 patients referred for 24-hour ambulatory BP monitoring (ABPM) with available values for at least one hour after waking and related them to all-cause mortality.

The median duration of follow-up on these patients was 6.5 years and fatal events occurred in 246 patients. The researchers observed no significant gender differences between patients who died and those who did not.

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Only the one-hour morning surge (MS)—the difference between average BP one hour before and after waking—was related to mortality. In adjusted analyses, the researchers found that those patients with one-hour MS above a median of 12 mm Hg had a significant 39% lower risk of dying, according to a report in the American Journal of Hypertension (published online ahead of print). Non-dippers had a significant 51% decrease in death risk.

Previous studies investigating this question have had conflicting results about the effect of MS on mortality. To date, no standard MS definition is available.

The researchers noted that “we found that the decrease of mortality associated with MS was significant in patients that are not recognized as dippers by the conventional definition.”

Although the study has some strengths, it also had limitations. It was retrospective and only looked at all-cause mortality. In addition, investigators did not have information on smoking, hyperlipidemia, previous cardiovascular diseases, and the class of antihypertensive treatment.