Extended In-office BP Monitoring Could Reduce Hypertension Overtreatment

Family Physician Calls for New BP Monitoring Standards, Protocols

March 22, 2017 01:58 pm News Staff

Previous research has suggested as many as one-third of patients with hypertension who are seen in a clinical setting have white-coat hypertension, which often leads to overtreatment.

However, automated office blood pressure monitoring for 30 minutes (OBP30) in the clinic may dramatically reduce the potential for overtreatment of these patients. That's according to a new study(www.annfammed.org) published in the March/April issue of Annals of Family Medicine.

The research compared OBP30 with routine OBP readings for different indications in primary care and evaluated how OBP30 influenced the medication prescribing of family physicians.

Here's What the Study Found

Researchers enrolled 201 patients who underwent OBP30 for medical reasons from February through July 2016 at a single health center in the Netherlands. Patients' OBP30 results were compared to their last preceding routine OBP reading. Physicians were asked why they ordered OBP30, how they treated their patients who underwent OBP30 and how they would have treated their patients without it.

The mean age of these patients was 68.6; about 57 percent were women, about 20 percent had cardiovascular disease and about 20 percent had diabetes.

Story highlights
  • A recent study in Annals of Family Medicine found automated office blood pressure monitoring for 30 minutes (OBP30) could reduce overtreatment of patients with white-coat hypertension.
  • Researchers enrolled 201 patients who underwent OBP30 for medical reasons from February through July 2016 at a single health center in the Netherlands.
  • The mean systolic OBP30 was, on average, 22.8 mm/Hg lower than the mean systolic OBP, and the mean diastolic OBP30 was, on average, 11.6 mm/Hg lower than the mean diastolic OBP.

Physicians who were interviewed said the most important reasons they ordered OBP30 were suspected white-coat hypertension, new diagnosis of hypertension, inconsistent office readings, monitoring of medication effect, suspected therapy resistance and suspected episodes of hypotension.

Researchers found that OBP30 achieved results similar to those seen with 24-hour ambulatory blood pressure monitoring (ABPM) but said OBP30 is a much more convenient option.

Overall, patients had lower blood pressure readings with use of OBP30 than with OBP, including patients not suspected of having white-coat hypertension. Specifically, the mean systolic OBP30 was, on average, 22.8 mm/Hg lower than the mean systolic OBP, and the mean diastolic OBP30 was, on average, 11.6 mm/Hg lower than the mean diastolic OBP.

The differences between OBP30 and OBP were greater for patients ages 70 and older in both systolic and diastolic BP.

Probably the most significant finding from this study was that based on OBP alone, physicians said they would have started or intensified hypertension medication regimes in about 79 percent of the studied cases. However, with the results of OBP30 available, this number sharply decreased to about 25 percent.

The authors said further research on this subject is needed to replicate the results in other clinical settings.

"The influence of OBP30-based blood pressure treatment on the number of medications prescribed, and on the occurrence of side effects and cardiovascular morbidity and mortality, should be evaluated," they suggested.

"In our study, the use of OBP30 in this select patient population led to much less intensification of antihypertensive medications regimens. OBP30 is a promising method to reduce overtreatment of white-coat hypertension in primary health care."

FP Calls for Changes in BP Monitoring

In an accompanying editorial,(www.annfammed.org) AAFP member Lee Green, M.D., M.P.H., professor and chair of the Department of Family Medicine at the University of Alberta, Edmonton, Canada, suggested that routine OBP and standardized OBP measurement (i.e., when the patient is seated and at rest for five minutes, with feet on the floor, back supported and arm supported at mid-chest height) should no longer be used to diagnose or modify hypertension treatment. Even when standardized OBP is done correctly, he noted, it is neither consistent and repeatable nor the best predictor of outcomes.

Green also said some clinicians think that although white-coat hypertension is less dangerous than sustained hypertension, it can still lead to more adverse outcomes than normotension and, therefore, should be treated. More recent research calls that thinking into question, however, furthering concerns about overtreatment.

According to Green, the "gold standard" of blood pressure measurement is 24-hour ABPM. But the problem with that method is that it can be costly, cumbersome and impractical for routine monitoring.

As for home monitoring, he observed, this method "can be very useful for those patients motivated to do it reliably, but what about everyone else?"

During the past 15 years, said Green, a significant body of evidence has emerged in primary care practices that supports the use of automated office blood pressure (AOBP) monitoring, during which readings are collected while patients sit undisturbed, a total of six times over a five- to 10-minute period.

Based on all of these findings, he suggested AOBP and OBP30 be used preferentially to either routine or standardized OBP because they more closely approximate (for daytime pressures) continuous ABPM. Of course, making such a change means practices would need to update their equipment, change their thinking on diagnosis and treatment thresholds, choose a method and implement the choice properly.

Green said a well-done, practice-based research network study comparing AOBP and OBP30 would be an important first step. And because the Systolic Blood Pressure Intervention Trial (SPRINT)(www.sprinttrial.org) used an abbreviated AOBP with just three measurements, he said it would be wise to include it in a comparison as well.

"We need to know whether AOBP or abbreviated AOBP, done in a few minutes, are just as good as a 30-minute protocol, or if there is a convenience/accuracy tradeoff we need to consider," Green said.

Next, thresholds would need to be rethought. The threshold of 140/90 mm/Hg for Stage 1 hypertension in patients younger than age 60 came from collective studies that used SOBP.

"Home and continuous ambulatory blood pressures run lower, and as AOBP and OBP30 closely approximate daytime ambulatory pressures, using 140/90 mm/Hg would result in underdiagnosis and undertreatment," Green said.

He referenced a July 27, 2015, article(hyper.ahajournals.org) in Hypertension that provided observational evidence based on patient-oriented outcomes supporting the use of 135/85 mm/Hg as a threshold, at least for the population of adults ages 65 and older it studied.

"Replication and extension to younger populations, and to patients with higher risk profiles, is needed," he said. "Ideally, the evidence for practice should come from practice -- again suggesting that practice-based research networks are the best laboratories."

Finally, Green said changing how health care professionals take BP in clinical settings may be a challenge as well, as both AOBP (standard or abbreviated) and OBP30 require preparing the patient and machine and then leaving them undisturbed while the measurements are taken.

"If we are to avoid overdiagnosing and overtreating due to the white-coat effect, we 'white coats' need to stay out of the room," he said, adding that taking off the coat won't fool anyone's sympathetic nervous system.

This protocol likely wouldn't be too hard for some practices, but others would need to change routines and possibly even rearrange offices.

"Getting it right will be a good use for our teams' quality improvement skills," Green said. "Because hypertension treatment matters so much to so many, we owe it to our patients to get it right."

Related AAFP News Coverage
Joint Hypertension Guideline Released
AAFP, ACP: Lower Older Adults' SBP to Below 150 mm Hg

(1/18/2017)

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