Extreme fluctuations in BP may be as deadly as a consistent high
Extreme fluctuations in systolic blood pressure (SBP) between doctor visits for an extended period of time was associated with an increased risk of death from any cause than those with less extreme variability in BP, suggests a study presented at the AHA Scientific Sessions 2017.
“The takeaway from the study is, if you allow your BP to be uncontrolled for any period of time, or notice big changes in your BP between doctor visits, you increase your risk of stroke, heart attack, kidney or heart failure, or even death,” said study lead investigator Dr Brian Clements from the Intermountain Medical Center Heart Institute in Salt Lake City, Utah, US.
Modelling the study after the largest hypertension trial to date, ALLHAT, the researchers analysed SBP records of 10,903 patients (mean age 71.5 years, 61 percent women) who had ≥7 SBP measurements between 2007–2011 for visit-to-visit SBP variability (VVV). After the seventh measurement, they were followed for at least 5 years for all-cause mortality. The fully adjusted Cox regression models accounted for differences in demographics, mean SBP, 29 medications, and 20 comorbidities recorded at the seventh SBP measurement. A total of 3,013 patients (27.6 percent) died during follow-up.
For every 10 percent increase in the coefficient of variation (CoV), ie, VVV normalized to the mean SBP (VVV divided by mean SBP), the risk of all-cause mortality as a continuous variable increased by 18 percent after fully adjusting for the confounders listed above (adjusted hazard ratio [adjHR], 1.18; p<0.001). [AHA 2017, abstract 16574]
Comparison between CoV quartiles also revealed a significant univariable association between the forth vs the first quartiles (HR, 1.41; p<0.001), which persisted with age adjustment (HR, 1.25; p<0.001). Although the magnitude of association was somewhat attenuated in the fully adjusted model, the results remained significant (HR, 1.12; p=0.035).
“The call to action for patients as a result of this study is to do everything they can to control their BP on a regular basis,” said Clements. “Eat healthy foods, exercise regularly, and if your doctor has prescribed you medications for your BP, be sure and take them consistently. Because any time your BP is out of control, you’re at higher risk of injury or death.”
With regards to what can be done to minimize variability in BP measurements, Clements recommended that people control their environment during BP measurement. For example, rest for 15 minutes before measurement, and avoid doing stress-causing things. He also advised that people should use a BP cuff that fits, avoiding one that is too tight or too loose.
“BP is one of those numbers we encourage people to keep track of, as it’s one indicator of your health heart,” said Clements, concluding that, “VVV [normalized to the mean SBP (as CoV)] is an independent predictor of all-cause mortality.”