ABPM Beats Office and Home BP Tests for Predicting CVD

Shelley Wood

June 14, 2014

ATHENS, GREECE — Bad news for advocates of home blood-pressure monitoring: researchers in Finland who performed a three-way analysis of office, home, and 24-hour ambulatory blood pressure monitoring (ABPM) say that while both out-of-office measures were superior to office measurements, ambulatory monitoring came out on top[1].

Dr Teemu Niiranen (National Institute for Health and Welfare, Turku, Finland) presented the results of the study here at HYPERTENSION 2014 , a joint conference of the European Society of Hypertension (ESH) and the International Society of Hypertension (ISH); they were also published early online in Hypertension.

"Everybody has agreed that home and ABPM are better than office measurements, but it's been quite unclear, with home or ABPM, whether one is better than the other," he told heartwire . "ABPM is quite expensive, and many people don't like it because it keeps pumping around the arm." By contrast, home monitoring is considerably cheaper and more convenient for patients, he said.

Support for one or the other had broken into two distinct teams, Niiranen said, adding that much of his research has come out in support of the home BP-monitoring team. Now, with these new results, "I'm a bit disappointed, because my team didn't win," he joked.

In fact, Niiranen noted in his talk, home and ABPM are typically used as complementary methods, but there are very scarce data comparing home and ABPM in a prognostic setting, "and it's unresolved whether ABPM is superior to home BP in predicting cardiovascular outcomes," he explained.

Out-of-Office BP Tests

Dr Teemu Niiranen

Niiranen and colleagues looked at two groups of patients—264 patients drawn from the general population and another 238 patients newly diagnosed with hypertension at the study outset, for a total of 502 patients. All of the initial patient measurements were taken between 1992 and 1996, allowing for a mean of 16 years of follow-up. Mortality and cardiovascular-event data, including CV mortality, nonfatal MI, nonfatal stroke, hospitalization for HF, and coronary interventions, were collected from national mortality and hospital discharge registers, covering every hospital in Finland.

After adjustment for sex, age, use of antihypertensive medications, smoking status, body-mass index (BMI), glucose, and total cholesterol, hazard ratios per 1/1-mg-Hg increases in blood pressure were greatest for ABMP, followed by nighttime home monitoring and daytime home monitoring, with office BP having the weakest predictive power for subsequent events. When all blood-pressure measurements were entered into the model simultaneously, only 24-hour ambulatory systolic and diastolic BPs were statistically significantly associated with subsequent events.

Similar results were seen when the general population and newly diagnosed hypertensive patients were analyzed separately, Niiranen said.

High-Quality Measurements

Of note, office measurements were "very thoroughly done" in the study, consisting of four duplicate measurements taken at one-week intervals: "no one actually does that in practice," he said. For the home measurements, patients measured their blood pressure twice, in the morning and evening, for a period of one week. For ABPM, patients wore monitors that continuously measured BP in 15-minute intervals during the day and in 30-min intervals at night.

But even with office BP measured so rigorously, "home and ambulatory were still better," he said. "So the main message is that hypertension guidelines should move away from office measurements to out-of-office measurements, as some have done."

In the newest UK guidelines, for example, "you can't diagnose hypertension any more, solely by using office measurements. . . . Ambulatory has been presumed to be the gold standard, but now there is some proof for that. This is not just a matter of opinion anymore."

Niiranen and colleagues have another question they want to look at, and that's how ABPM compares with new home-BP monitors, which can be programmed to measure nighttime BPs.

"With the ambulatory measurements, almost everybody wakes up [when the cuffs inflate], but with the tests we've been doing with the home nighttime measurements . . . many people say they don't even wake up, since it is only three times at one-hour intervals," he said.

If home-based measurements yield closer predictive power to 24-hour measurements using these cheaper devices, "it would be a good thing for the patient and for society," he said.

Niiranen disclosed receiving a single lecture honorarium from Omron Healthcare.

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