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Construct Overview of Hypertension

Please note that this section is an archive and is no longer being updated.

Background

Hypertension refers to a condition in which there is greater than optimal force against the arteries during and/or between heartbeats. Hypertension is defined as a systolic blood pressure (pressure during heartbeat) >= 140 mmHg and/or diastolic blood pressure (pressure between beats) >= 90 mm Hg.^1,2 A recently designated classification of “prehypertension” is defined as a systolic blood pressure of 120-139 mm Hg or diastolic blood pressure of 80-89mm Hg.² The American Heart Association has estimated that 65 million Americans have hypertension, and 30% are not aware that they have the condition.¹ Hypertension is an established risk factor for several serious conditions, including myocardial infarction (heart attack), stroke, heart failure, and kidney disease.²

Although it is a significant health risk factor, hypertension itself is often asymptomatic. However, some studies have suggested that individuals with hypertension enjoy somewhat lower quality of life than those without the condition.³ Treatment with antihypertensive medication is associated with several well established side effects, including fatigue, nausea, dizziness, and sexual dysfunction.⁴ Findings concerning the impact of treatment on quality of life have been inconsistent, with some studies reporting positive effects and others reporting negative effects on health-related quality of life.^3-5 These inconsistencies may reflect differences in research populations, study designs, drug types, dosages, or measurement factors across studies.

VA Relevance

Hypertension is the most prevalent chronic medical condition diagnosed among VA health care system users, affecting 36.8% (approximately 1.2 million) of the VA patient population in 1999 and associated with over $6,000 in costs per patient.⁶ However, research suggests that, as in the general U.S. population, hypertension may not be managed effectively in a large proportion of VA users with the condition. Two studies of hypertensive patients treated at VA medical centers have found that fewer than half were able to attain well-controlled blood pressure (i.e., no longer meeting the criteria for hypertension, < 140/90).^7,8

To assess hypertension, an accurate reading of systolic and diastolic blood pressure must be obtained using a calibrated instrument, typically a mercury sphygmomanometer. Because transient increases in blood pressure can occur as a result of physical activity or emotional states such as anxiety, the setting and circumstances of the blood pressure assessment are potential sources of measurement error.² Although standardized procedures have been recommended to improve the comparability and reliability of measurements over time, a measurement of blood pressure at any given moment is an indirect estimate of a hypothetical “actual” blood pressure. Thus, individual blood pressure measurements may be viewed as estimates of a presumably stable latent trait, subject to error from multiple sources.⁹

Measurement

The “white coat effect,” a common phenomenon in which the clinic setting itself is associated with an elevation in blood pressure, can increase error in the diagnosis and treatment of hypertension. Further complicating this problem, the white coat effect appears to be more pronounced among hypertensive than non-hypertensive patients. Ambulatory or home monitoring of blood pressure may be helpful in validating blood measurements taken in the clinic when “white coat hypertension” is suspected.^2,10

Self-report instruments are often used to assess symptom severity and health-related quality of life in individuals with hypertension. The use of generic (i.e., non-disease specific) health surveys has been common in this type of research. However, many clinical trials claiming to assess “quality of life” as an outcome have actually used a set of symptom-specific measures (e.g., questionnaires to specifically assess psychological well-being, sleep dysfunction, etc.) for this purpose.^11,12 Relatively few studies have employed established instruments that are specially designed for assessment of hypertensive populations.

Failure to define “quality of life” in specific terms is a limitation of many previous studies of hypertension that have attempted to measure this construct.^4,12 Hypertension-specific measures should be constructed to measure the full range of possible influences on well being associated with the condition. In addition, outcome measures designed for use among hypertensive patients should be sensitive to the effects of both the condition itself and to the effects of treatment, including unwanted side effects.¹³

Through literature review, METRIC identified two commonly used self-report instruments for use in evaluating the effects of hypertension and its treatment. These are ranked according to number of citations, as determined by the ISI Web of Knowledge.¹⁴ What follows is a brief summary of each instrument and three applicable references.

Most Frequently Cited Instruments

1. Physical Symptoms Distress Index
   [15 Citations]
2. Vital Signs Quality of Life Questionnaire
   [14 Citations]

1. American Heart Association. Heart disease and stroke statistics – 2006 update. Accessed January 2006. Available: http://www.americanheart.org/presenter.jhtml?identifier=3000090.
2. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, Jones DW, Materson BJ, Oparil S, Wright JT Jr, Roccella EJ; National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA 2003;289:2560-2572. [Abstract]
3. Li W, Liu L, Puente JG, Li Y, Jiang X, Jin S, Ma H, Kong L, Ma L, He X, Ma S, Chen C. Hypertension and health-related quality of life: an epidemiological study in patients attending hospital clinics in China. J Hypertens 2005;23:1637-1676. [Abstract]
4. Hunt SM. Quality of life claims in anti-hypertensive therapy. Qual Life Res 1997;6:185-191. [Abstract]
5. Beto JA, Bansal VK. Quality of life in treatment of hypertension: a metaanalysis of clinical trials. Am J Hypertens 1992;5:125-133. [Abstract]
6. Yu W, Ravelo A, Wagner TH, Phibbs CS, Bhandari A, Chen S, Barnett PG. Prevalence and costs of chronic conditions in the VA health care system. Med Care Res Rev 2003;60(Suppl);146S-167S. [Abstract]
7. Berlowitz DR, Ash AS, Hickey EC, Friedman RH, Glickman M, Kader B, Moskowitz MA. Inadequate management of blood pressure in a hypertensive population. N Engl J Med 1998;339:1957-1963. [Abstract]
8. Johnson ML, Pietz K, Battleman DS, Beyth RJ. Therapeutic goal attainment in patients with hypertension and dyslipidemia. Med Care 2006;44:39-46. [Abstract]
9. Sechrest L. Validity of measures is no simple matter. Health Serv Res 2005;40:1584-1604. [Abstract]
10. Gerin W, Ogedegbe G, Schwartz JE, Chaplin WF, Goyal T, Clemow L, Davidson KW, Burg M, Lipsky S, Kentor R, Jhalani J, Shimbo D, Pickering TG. Assessment of the white-coat effect. J Hypertens 2006;24:67-74. [Abstract]
11. Côté I, Grégoire J-P, Moisan J. Health-related quality-of-life measurement in hypertension. Pharmacoeconomics 2000;18:435-450. [Abstract]
12. Coyne KS, Davis D, Frech F, Hill MN. Health-related quality of life in patients treated for hypertension: a review of the literature from 1990 to 2000. Clin Ther 2002;24:142-169. [Abstract]
13. Bulpitt CJ, Fletcher AE. The measurement of quality of life in hypertensive patients: a practical approach. Br J Clin Pharm 1990;30:353-364. [Abstract]
14. ISI Web of Knowledge. Accessed January 2006. Available: http://isi01.isiknowledge.com/portal.cgi/wos/.