The Role of Home Blood Pressure Monitoring in Hypertension Control

Abstract

Hypertension is estimated to affect as many as 50 million adults in the United States. Despite nationally developed, evidence‐based guidelines for care and the availability of numerous effective medications for the treatment of hypertension, control rates for this condition remain very low. Only 21%–27% of diagnosed patients in the United States are controlled to blood pressure levels of <140/90 mm Hg. 1 Factors contributing to the poor hypertension control rate include adherence issues, variation in provider practice patterns, and the lack of a systematic approach to tracking and maintaining blood pressure control. Home monitoring combined with systematic treatment and follow‐up by skilled health care professionals can have a positive impact in all three of these areas.

Suboptimal adherence to blood pressure‐lowering medications has been estimated to occur in 30%–50% of patients under treatment. ² The symptomless nature of the condition contributes largely to poor drug adherence. Moreover, while approximately 50%–60% of hypertensive patients require more than one medication in order to achieve control, it has been demonstrated that complex medication regimens contribute to poor treatment adherence. ³ Lack of social support, health beliefs, low perceived self‐efficacy, lack of follow‐up by the medical team, and unhealthy behaviors, such as tobacco dependence and excessive alcohol intake, can also negatively influence adherence. ⁴

VARIATION IN TREATMENT

Medical school education regarding hypertension and its management is often very fragmented. Some aspects of the condition are presented in various courses, such as pharmacology, biochemistry, and clinical medicine, but an integrated, comprehensive approach is often lacking. ⁵ Therefore, although hypertension is among the most common reasons for outpatient visits in the United States, its management by primary health providers may be inconsistent or based on outdated data. Often, physicians do not treat mild elevations in systolic pressure, particularly when they are unaccompanied by elevations in diastolic blood pressure. ⁶ In addition, with the length of appointments being limited in many clinical settings, hypertension frequently receives a lower priority than conditions that present a more imminent health risk or are accompanied by symptoms that are troublesome to the patient.

MAINTAINING CONTROL

Hypertension is a chronic condition and its ill effects on cardiovascular health often develop slowly. Therefore, systems to provide consistent surveillance and to assist patients in maintaining blood pressure control over time are critical to reducing mortality and morbidity. One approach to improving hypertension control is to provide patients with the necessary tools to be active partners in the management of this condition. By using home blood pressure monitors and becoming more proficient in self‐care skills, such as lifestyle modification and medication adherence, patients can truly begin to take responsibility for their own hypertension control. In order to assist the patient toward this goal, there must be a system in place to provide education, lifestyle counseling, consistent, evidence‐based medication adjustment, and routine follow‐up. Although physicians can provide this level of care, it may be more efficacious and cost‐effective to use nurses or pharmacists as care managers in this role. ⁷ , ⁸

HOME MONITORING

Innovative technology has increased the availability of accurate, easy to use, moderately priced home blood pressure measuring devices. When choosing a home monitor, it is advisable to ensure that the device is approved by the Food and Drug Administration and meets the Association for the Advancement of Medical Instrumentation standards for sphygmomanometers. The most accurate devices measure blood pressure in the brachial artery. Devices that measure blood pressure at the wrist or finger tend to provide less reliable readings than those that measure blood pressure in the upper arm. ⁹

The choice of an accurate device is only the first step in obtaining reliable home readings. Although the quality of approved devices is very high, the accuracy of any home device should be checked against a mercury sphygmomanometer by a health care professional. Verifying the accuracy of home readings is particularly important when home readings are used as a basis for making medication adjustments. In addition, the patient must be taught proper technique for obtaining an accurate reading. Attention should be paid to appropriate cuff size, positioning, and timing of the measurements. Simple step‐by‐step written or video instructions and return demonstration by the patient, with an opportunity to assess and correct the technique, are key to ensuring the accuracy of home readings.

Choice of an accurate device and proper measurement technique alone do not ensure accurate reporting of home blood pressure readings. While most self‐reported blood pressure measurements are reliable, erroneous reporting often occurs, particularly when patients display elevated blood pressure readings. ¹⁰ Therefore, the prudent clinician will augment home reading data with periodic clinic measurements. Home blood pressure devices equipped with modem connections offer an alternative to verification by clinical measurement. These devices can transmit readings electronically via modem to a central reporting service or Web site, so that a patient does not need to record blood pressures manually and does not have an opportunity to alter the values measured by the device. In addition to eliminating self‐reporting errors, the modem devices and services provide graphic and statistical data on blood pressure and pulse readings that are readily accessible to the patient and health care provider. This powerful communication tool and provides a compelling display of blood pressure trends that may be serve to enhance patient adherence to treatment.

Home monitoring supports physicians and other health care professionals in caring for patients with hypertension by providing plentiful data. Rather than basing a medication change on only two or three clinic readings spaced several weeks apart, the clinician whose patient employs home monitoring has numerous readings available for consideration. Home monitoring highlights changes in blood pressure over the course of a single day and also identifies trends over longer periods of time. This type of information can influence medication decision‐making. For example, a patient whose blood pressure is high in the morning may have normal levels in the evening. In this situation, control might be achieved by merely changing the timing of the medication from morning to evening dosing. This allows a patient to avoid increasing doses or adding medications, thereby reducing the possibility of adverse effects. In another typical scenario, a health care provider may hesitate to treat a patient with a few mildly elevated clinic readings. However, if that patient demonstrates, by home readings, that his or her blood pressure is consistently elevated, the clinician may be more likely to begin treatment, and the patient may be more willing to accept and adhere to treatment, given the magnitude of the data. Treatment of even mild blood pressure elevations has been found to significantly decrease mortality from heart disease across populations. ¹¹ Finally, monitoring blood pressure in the home setting also helps to avoid the pressor response (“white coat hypertension”) experienced by many patients in the clinic. ¹²

One effective method of helping patients to achieve blood pressure control is the use of a care management system directed by physicians but conducted and managed by nurses or pharmacists. ⁷ , ⁸ This type of care management has several advantages. Medication protocols that reflect evidence‐based decision‐making can be developed and followed in a consistent manner. Simple software or more traditional filing systems can be used to track patients and prompt the care manager to contact the patient at appropriate intervals, bolstering medication compliance and blood pressure control over time. A financial advantage, at least in a health maintenance organization setting, is that accurate home blood pressure measurement and reporting, coupled with telephonic medication adjustment and lifestyle modification counseling, can serve to significantly reduce the number of office visits required to achieve goal blood pressures. In addition, programs designed to encourage a patient to take an active role in blood pressure monitoring often result in improved adherence to the treatment plan.¹³ Once control is achieved, home monitoring and occasional contact by the care manager ensure ongoing surveillance and support maintenance of desired blood pressure ranges.

It is important to note that not all patients are candidates for home monitoring. For individuals who are particularly anxious, home monitoring can have a deleterious effect on control and management of hypertension. The anxious patient often becomes alarmed by a single elevated reading and feels compelled to repeat readings frequently in hopes of allaying the fear. In these situations, anxiety tends to mount with each reading and can make subsequent readings higher still. This often prompts repeated and perhaps unnecessary contacts with the health care system. In a situation such as this, neither the patient nor the health care system is well served by home blood pressure monitoring. For anxious individuals, traditional care, perhaps augmented by behavioral medicine services, is likely to be most appropriate.

Patients with very large or very conical arms or a distinct muffle at phase IV of the Korotkoff sounds may not be able to obtain accurate blood pressure readings with automated devices. In these cases, either home monitoring with aneroid devices or clinic readings with a mercury or aneroid sphygmomanometer may be indicated.

Another barrier to home monitoring is cost. Although reasonably priced devices are available, they are still expensive enough to preclude many individuals from purchasing them. Modem devices and services are even more expensive. Third‐party payer reimbursement would vastly improve accessibility to home monitoring by making the devices available to more patients who might benefit from their use. Currently, very few insurance plans cover the costs of such devices.

CONCLUSION

Despite readily available tools to achieve widespread hypertension control, this condition remains woefully undertreated, placing large numbers of individuals at risk for cardiovascular sequelae. Increased use of evidence‐based approaches to hypertension treatment and the development of focused‐care management programs that encourage collaborative care have the potential to vastly improve control rates. Hypertension control is a Health Plan Employer Data & Information Set quality goal for the year 2001. The pressure brought to bear by this level of scrutiny is another powerful reason to re‐examine, update, and improve our treatment strategies for patients with hypertension. Home monitoring, lifestyle counseling, and appropriate medication management, particularly in the context of a systematized, evidence‐based approach to long‐term control, constitute a powerful tool for successful hypertension management and improved health outcomes for the hypertensive population.

Acknowledgment: The authors would like to acknowledge and thank Robert F. DeBusk, MD, Director of Stanford Cardiac Rehabilitation Program, for his assistance in editing this report.