Screening for High Blood Pressure in Adults: U.S. Preventive Services Task Force Recommendation Statement

Who developed these recommendations? The U.S. Preventive Services Task Force (USPSTF) developed these recom-mendations. The USPSTF is a group of health experts that reviews published research and makes recommendations about preventive health care. What is the problem and what is known about it so far? High blood pressure (hypertension) is a common chronic condition in adults. High blood pressure strains the heart and harms blood vessels. It increases the risk for such complications as heart problems, stroke, kidney problems, and eye problems. Diet, exercise, and drugs can reduce blood pressure and decrease the chances of these complications. People with high blood pressure usually do not have symptoms, so they often do not know that they have it until someone measures their blood pressure. Screening for high blood pressure involves routinely measuring blood pressure even in people who feel well. Health care organizations have recommended screening for high blood pressure because it is common, measurement is easy and safe, symptoms usually do not appear until complications develop, and good treatments are available. The benefits of screening include prevention of complications. The harms of screening include prescription of drugs that may cause adverse effects in people with early high blood pressure. The USPSTF wanted to review research published since its last recommendation about blood pressure screening in 2007 to update its recommendation. The USPSTF was particularly interested in 2 issues. First, when should screening be repeated after an initial screening result is normal? Second, which methods are best for confirming high blood pressure found on initial screening? In addition to measuring blood pressure in a medical setting (office monitoring), ambulatory or home blood pressure monitoring may be used to confirm hypertension. Ambulatory blood pressure monitoring devices are small, portable machines that record blood pressure at regular intervals over 12 to 24 hours while patients go about their normal activities. Home blood pressure monitoring uses automated devices that let patients record blood pressure at home. Not all home monitors have undergone technical validation according to recommended protocols. How did the USPSTF develop these recommendations? The USPSTF reviewed the research published since its 2007 recommendation about the accuracy of different methods for confirming hypertension after an initial positive screening result and about the best frequency for screening. What did the authors find? The authors found clear evidence that the benefits of screening for hypertension outweigh the risks. Ambulatory blood pressure monitoring is the best method for diagnosing hypertension, and home blood pressure monitoring may be acceptable if ambulatory monitoring is not possible. Good information about the best frequency for screening is not available. What does the USPSTF recommend that patients and doctors do? The USPSTF recommends screening for high blood pressure in adults aged 18 years or older and taking measurements outside of medical settings to confirm high blood pressure before starting treatment. What are the cautions related to these recommendations? A recent study may result in changes to the definition of high blood pressure.


T he U.S. Preventive Services Task Force (USPSTF)
makes recommendations about the effectiveness of specific preventive care services for patients without related signs or symptoms.
It bases its recommendations on the evidence of both the benefits and harms of the service and an assessment of the balance. The USPSTF does not consider the costs of providing a service in this assessment.
The USPSTF recognizes that clinical decisions involve more considerations than evidence alone. Clinicians should understand the evidence but individualize decision making to the specific patient or situation. Similarly, the USPSTF notes that policy and coverage decisions involve considerations in addition to the evidence of clinical benefits and harms.

SUMMARY OF RECOMMENDATION AND EVIDENCE
The USPSTF recommends screening for high blood pressure in adults aged 18 years or older. (A recommendation) The USPSTF recommends obtaining measurements outside of the clinical setting for diagnostic confirmation before starting treatment (see the Clinical Considerations).
See Figure 1 for a summary of the recommendation and suggestions for clinical practice.
Appendix Table 1 describes the USPSTF grades, and Appendix Table 2 describes the USPSTF classification of levels of certainty about net benefit (both tables are available at www.annals.org).
The USPSTF also assessed the accuracy of these blood pressure measurements and methods in confirming the diagnosis of hypertension. In addition, it reviewed data on optimal screening intervals for diagnosing hypertension in adults.

Benefits of Early Detection and Treatment
The USPSTF found good evidence that screening for and treatment of high blood pressure in adults substantially reduces the incidence of cardiovascular events.

Harms of Early Detection and Treatment
The USPSTF found good evidence that screening for and treatment of high blood pressure has few major harms.

USPSTF Assessment
The USPSTF concludes with high certainty that the net benefit of screening for high blood pressure in adults is substantial.

CLINICAL CONSIDERATIONS Patient Population Under Consideration
This recommendation applies to adults aged 18 years or older without known hypertension.

Office Blood Pressure Measurement
Office measurement of blood pressure is most commonly done with a manual or automated sphygmomanometer. Little research has been done on the best approach to measuring blood pressure in the office setting. Most clinical trials of hypertension treatment, at a minimum, used the mean of 2 measurements taken while the patient was seated (some used the mean of the second and third measurements), allowed for at least 5 minutes between entry into the office and blood pressure measurement, used an appropriately sized arm cuff, and placed the patient's arm at the level of the right atrium during measurement. Multiple measurements over time have better positive predictive value for hypertension than a single measurement. Automated office blood pressure, which is an average of multiple automated measurements taken while the patient is alone in a room, may yield results similar to those of daytime ABPM (4,5). Blood pressure is affected by various short-term factors, such as emotions, stress, pain, physical activity, and drugs (including caffeine and nicotine). In addition to within-patient temporal variability, isolated clinic hypertension in the medical setting and in the presence of medical person-

Population
Adults aged ≥18 y without known hypertension Recommendation Screen for high blood pressure; obtain measurements outside of the clinical setting for diagnostic confirmation.

Risk Assessment
Persons at increased risk for high blood pressure are those who have high-normal blood pressure (130-139/85-89 mm Hg), those who are overweight or obese, and African Americans.

Screening Tests
Office measurement of blood pressure is done with a manual or automated sphygmomanometer. Proper protocol is to use the mean of 2 measurements taken while the patient is seated, allow for ≥5 min between entry into the office and blood pressure measurement, use an appropriately sized arm cuff, and place the patient's arm at the level of the right atrium. Multiple measurements over time have better positive predictive value than a single measurement.
Ambulatory and home blood pressure monitoring can be used to confirm a diagnosis of hypertension after initial screening.

Screening Interval
Adults aged ≥40 y and persons at increased risk for high blood pressure should be screened annually. Adults aged 18 to 39 y with normal blood pressure (<130/85 mm Hg) who do not have other risk factors should be rescreened every 3 to 5 y.

Treatment and Interventions
For nonblack patients, initial treatment consists of a thiazide diuretic, calcium-channel blocker, angiotensin-converting enzyme inhibitor, or angiotensin-receptor blocker. For black patients, initial treatment is thiazide or a calcium-channel blocker. Initial or addon treatment for patients with chronic kidney disease consists of either an angiotensin-converting enzyme inhibitor or an angiotensin-receptor blocker (not both).

Balance of Benefits and Harms
The net benefit of screening for high blood pressure in adults is substantial.
For a summary of the evidence systematically reviewed in making this recommendation, the full recommendation statement, and supporting documents, please go to www.uspreventiveservicestaskforce.org. nel (known as "white coat" hypertension) is welldocumented. Epidemiologic data suggest that 15% to 30% of the population believed to have hypertension may have lower blood pressure outside of the office setting (1). The disadvantages of diagnosing hypertension solely in the office setting include measurement errors, the limited number of measurements that can be made conveniently, and the confounding risk for isolated clinic hypertension.

Ambulatory and Home Blood Pressure Monitoring
In addition to office blood pressure measurement, ABPM and HBPM may be used to confirm a diagnosis of hypertension after initial screening. Ambulatory blood pressure monitoring devices are small, portable machines that record blood pressure at regular intervals over 12 to 24 hours while patients go about their normal activities and while they are sleeping. Measurements are typically taken at 20-to 30-minute intervals. Home blood pressure measurement devices are fully automated oscillometric devices that record measurements taken from the patient's brachial artery. Many of these devices are available for retail purchase, and some have undergone technical validation according to recommended protocols.
The USPSTF found convincing evidence that ABPM is the best method for diagnosing hypertension. Although the criteria for establishing hypertension varied across studies, there was significant discordance between the office diagnosis of hypertension and 12-and 24-hour average blood pressures using ABPM, with significantly fewer patients requiring treatment based on ABPM ( Figure 2) (30). Elevated ambulatory systolic blood pressure was consistently and significantly associated with increased risk for fatal and nonfatal stroke and cardiovascular events, independent of office blood pressure ( Figure 3) (30). For these reasons, the USPSTF recommends ABPM as the reference standard for confirming the diagnosis of hypertension.
Good-quality evidence suggests that confirmation of hypertension with HBPM may be acceptable. Several studies showed that elevated home blood pressure was significantly associated with increased risk for cardiovascular events, stroke, and all-cause mortality, independent of office blood pressure ( Figure 4) (38 -41). However, fewer studies have compared HBPM with office blood pressure measurement, so the evidence is not as substantial as it is for ABPM (1). Therefore, the USPSTF considers ABPM to be the reference standard for confirming the diagnosis of hypertension. However, the USPSTF acknowledges that the use of ABPM may be problematic in some situations. Home blood pressure monitoring using appropriate protocols is an alternative method of confirmation if ABPM is not available. Measurements from the office, HBPM, and ABPM must be interpreted with care and in the context of the indi-

CLINICAL GUIDELINE
Screening for High Blood Pressure in Adults vidual patient. Patients with very high blood pressure or signs of end-organ damage may need immediate treatment.

Screening Interval
The USPSTF recommends annual screening for adults aged 40 years or older and for those who are at increased risk for high blood pressure. Persons at increased risk include those who have high-normal blood pressure (130 to 139/85 to 89 mm Hg), those who are overweight or obese, and African Americans. Adults aged 18 to 39 years with normal blood pressure (<130/85 mm Hg) who do not have other risk factors should be rescreened every 3 to 5 years. The USPSTF recommends rescreening with properly measured office blood pressure and, if blood pressure is elevated, confirming the diagnosis of hypertension with ABPM.

Treatment
The benefits of treatment of hypertension in preventing important health outcomes are welldocumented. Moderate-to high-quality randomized, controlled trials (RCTs) demonstrate the efficacy of treatment of the general population of persons aged 60 years or older to a target blood pressure of 150/90 mm Hg in reducing the incidence of stroke, heart failure, and coronary heart disease events. Similarly, RCTs demonstrate the efficacy of treatment of younger adults to a target diastolic blood pressure of less than 90 mm Hg in reducing cerebrovascular events, heart failure, and overall mortality (42). In the absence of sufficient RCT data, expert opinion has been used to establish a target systolic blood pressure of 140 mm Hg in adults younger than 60 years (42), and some experts believe that this should also be maintained in those aged 60 years or older (43). However, published results from a recently completed large RCT, the Systolic Blood Pressure Intervention Trial, are not yet available to inform current treatment goals. Clinicians should consult updated blood pressure treatment guidelines informed by this trial as they become available.
For nonblack patients, initial treatment consists of a thiazide diuretic, calcium-channel blocker, angiotensinconverting enzyme inhibitor, or angiotensin-receptor blocker. For black patients, initial treatment is thiazide or a calcium-channel blocker. Initial or add-on treatment for patients with chronic kidney disease consists of either an angiotensin-converting enzyme inhibitor or an angiotensin-receptor blocker (not both).

OTHER CONSIDERATIONS Suggestions for Implementation
Screening for high blood pressure may be done in the office setting by using the proper methods described previously. However, the USPSTF recommends confirmation outside of the clinical setting before a diagnosis of hypertension is made and treatment is started. Confirmation may be done by using HBPM or ABPM. Because blood pressure is a continuous value with natural variations throughout the day, repeated measurements over time are generally more accurate in establishing a diagnosis of hypertension. The USPSTF did not find evidence for a single gold standard protocol for HBPM or ABPM. However, both may be used in conjunction with proper office measurement to make a diagnosis and guide management and treatment options. Blood pressure cuffs used for HBPM should be compliant with sphygmomanometer stan-  Weights are from random-effects analysis. CV = cardiovascular; HF = heart failure; HR = hazard ratio; MI = myocardial infarction.

Research Needs and Gaps
Most of the evidence supports ABPM as the best method for confirming a diagnosis of hypertension. More research is needed on the accuracy of HBPM versus ABPM and the best HBPM protocols for follow-up of elevated office blood pressure. The diagnostic accuracy of blood pressure measurements taken by a visiting nurse or another health care worker in the home setting also merits more research. Self-use blood pressure measurement kiosks in community settings, such as pharmacies and grocery stores, may be frequently used by the public but are not regulated by the U.S. Food and Drug Administration. More research on the accuracy of kiosk measurements is needed. New technology has been developed that uses a wireless brachial blood pressure monitor that connects to a smartphone, a desktop computer, or the Internet for recording and analysis. More research is needed on the accuracy of these monitors, their use in primary prevention, and their association with long-term health outcomes.

Burden of Disease
Hypertension is a prevalent condition, affecting 29.1% of U.S. adults in 2011 to 2012 (45). Prevalence rates increase with age, from 7.3% in persons aged 18 to 39 years to 32.4% in those aged 40 to 59 years and to 65.0% in those aged 60 years or older. Non-Hispanic black adults have the highest prevalence (42.1%) compared with white (28.0%), Hispanic (26.0%), and Asian (24.7%) Americans. Uncontrolled hypertension is a risk factor for heart attack, stroke, and congestive heart failure and a major contributing factor to cardiovascular and all-cause mortality in the United States (46). Persons with high blood pressure often have no signs or symptoms of the condition; however, once diagnosed, it is usually amenable to treatment.

Scope of Review
In its previous evidence reviews, the USPSTF found substantial indirect evidence to support the effectiveness of screening for high blood pressure in adults (2,3). For the current recommendation statement, the USPSTF examined the diagnostic accuracy of different methods for confirming a diagnosis of hypertension after initial screening. The USPSTF also examined data to determine the optimal rescreening interval for diagnosing hypertension.

Effectiveness of Early Detection
The USPSTF found 1 new study that directly assessed screening for high blood pressure in an adult population (47). This study was a good-quality cluster RCT of community-based pharmacy screening in adults aged 65 years or older living in Ontario, Canada. Results showed 3 fewer annual cardiovascular-related hospitalizations per 1000 persons in the intervention group compared with the no-screening group (rate ratio, 0.91 [95% CI, 0.86 to 0.97]). However, because this study was limited to adults aged 65 years or older, the USPSTF concluded that there is still inadequate direct evidence about the benefits and harms of screening for hypertension in younger adults. Substantial indirect evidence continues to support the net benefit of screening for high blood pressure in adults aged 18 years or older (2, 3).

Office Blood Pressure Measurement
The USPSTF did not find evidence suggesting that a particular office blood pressure measurement protocol is more accurate than any other (1). Data comparing manual (ausculatory) versus automated office blood pressure measurement with a reference standard, such as ABPM, are lacking.
The USPSTF found that office blood pressure variably predicted true hypertension, as defined by the reference standard of ABPM. Isolated elevated clinic blood pressure was not confirmed after ABPM in approximately 5% to 65% of study participants (Figure 2) (1). Positive predictive values (with ABPM as the refer- Weights are from random-effects analysis. CV = cardiovascular; HR = hazard ratio; MI = myocardial infarction; TIA = transient ischemic attack.

CLINICAL GUIDELINE
Screening for High Blood Pressure in Adults ence standard) increased with the following factors: patient population characteristics, such as age; blood pressure; and the number of abnormal screening results before confirmation. Given the variability of office blood pressure in predicting sustained, true hypertension, confirmatory measurement is needed for patients with elevated blood pressure at the initial office screening.

Ambulatory and Home Blood Pressure Monitoring
The USPSTF found that elevated 24-hour ambulatory systolic blood pressure was consistently and significantly associated with stroke and other cardiovascular outcomes, independent of office blood pressure and with greater predictive value. Because of its large evidence base, ABPM is considered the best confirmatory test for hypertension. The USPSTF found 9 studies that evaluated the predictive value of 24-hour ABPM on long-term health outcomes (1). Four studies found that each 10 -mm Hg increment in ambulatory blood pressure (adjusted for office measurements) was significantly associated with increased risk for fatal and nonfatal stroke ( Figure 3) (31)(32)(33)(34). Six studies found that each 10 -mm Hg increment was associated with increased risk for fatal and nonfatal cardiovascular events, with hazard ratios ranging from 1.11 to 1.42 ( Figure 3) (31)(32)(33)(35)(36)(37).
Home blood pressure monitoring may also be a reasonable confirmatory method but has less evidence to support its use. Four good-quality studies found that elevated blood pressure with HBPM showed a significant association with increased risk for cardiovascular outcomes, with hazard ratios ranging from 1.17 to 1.39 ( Figure 4) (38 -41).

Screening Interval
No clinical trials randomly assigned patients to different rescreening intervals and evaluated clinical outcomes. Many observational studies have followed patients over time to determine how many develop hypertension at intervals of 1 to 5 years (1). These data are summarized in the Table. The percentage of patients who are diagnosed with hypertension after confirmatory monitoring is significantly higher among African Americans, persons with an initial high-normal blood pressure (130 to 139/85 to 89 mm Hg), those who are obese or overweight, and those older than 40 years (1). In most studies, the risk for hypertension exceeded 20% at 3 to 5 years in persons with at least 1 of these risk factors. Given the higher incidence of hypertension in populations with these risk factors, annual screening may be warranted for persons aged 40 years or older, African Americans of any age, and persons who are overweight or obese. Blood pressure exceeding the optimal level of less than 120/80 mm Hg may confer a graded risk; persons with blood pressure closest to the threshold for a diagnosis of hypertension have a higher incidence of hypertension at rescreening. Adults aged 18 to 39 years with no other risk factors have a low incidence of hypertension (about 1% to 6% at 2 years).
The USPSTF recommends rescreening with adequate office blood pressure measurement using the techniques described previously and, if indicated, confirmation with ABPM. Ambulatory blood pressure monitoring can be performed every year in high-risk persons and every 3 to 5 years in those at low risk (adults aged 18 to 39 years with no risk factors).

Potential Harms of Screening
The USPSTF found 9 studies that evaluated the harms of screening for high blood pressure (1). Four studies found no significant differences in psychological distress or quality of life before versus after participants were labeled with hypertension or prehypertension (48 -51). Four studies addressed harms associated with ABPM and found that use of the monitoring device was associated with sleep disturbances, discomfort, and restrictions in daily activities (52)(53)(54)(55). These studies suggest that the harms of screening may be relatively minor and short-term in nature. However, persons with isolated elevated clinic blood pressure who do not receive confirmatory ABPM or HBPM may be misdiagnosed with hypertension and could subsequently experience the more serious harms of unnecessary drug treatment. Misdiagnosis of hypertension is an area that warrants future research.

Estimate of Magnitude of Net Benefit
The USPSTF determined that the benefits of screening for high blood pressure in adults to prevent cardiovascular morbidity and mortality are substantial and that the harms of screening are small. The USPSTF concludes with high certainty that the net benefit of screening is substantial.

Response to Public Comment
A draft version of this recommendation statement was posted for public comment on the USPSTF Web site from 23 December 2014 to 26 January 2015. The USPSTF reviewed all public comments received in response. The USPSTF acknowledges the current barriers to implementation of its recommendation, including the availability and affordability of ABPM. In response, it revised the final recommendation to include HBPM as an alternative for confirming a diagnosis of hypertension when ABPM is not feasible. The USPSTF also pro- vided more information on the implementation of diagnostic confirmation and industry standards for home blood pressure monitors.

UPDATE OF PREVIOUS USPSTF RECOMMENDATION
This recommendation updates the 2007 reaffirmation recommendation statement on screening for high blood pressure in adults. The current statement recommends screening for high blood pressure using office blood pressure measurement and confirming a diagnosis of hypertension with ABPM. In addition, the USPSTF recommends optimal screening intervals for diagnosing hypertension in adults.

RECOMMENDATIONS OF OTHERS
The Eighth Joint National Committee does not address the diagnosis of hypertension in its 2014 guidelines (42). The Seventh Joint National Committee recommends screening for high blood pressure at least once every 2 years in adults with blood pressure less than 120/80 mm Hg and every year in adults with blood pressure of 120 to 139/80 to 89 mm Hg (56). The American Heart Association recommends blood pressure measurement at each regular health care visit or at least once every 2 years in adults with blood pressure less than 120/80 mm Hg (57). The American Academy of Family Physicians' recommendation is similar to that of the USPSTF (58). The American Congress of Obstetricians and Gynecologists recommends blood pressure screening as part of women's annual health care visits (59).