Recommendation: Blood pressure should be measured regularly in all persons aged 3 and above (see Clinical Intervention). Burden of Suffering Hypertension may occur in as many as 58 million Americans. It is a leading risk factor for coronary artery disease, congestive heart failure, stroke, renal disease, and retinopathy. These complications of hypertension are among the most common and serious diseases in the United States, and successful efforts to lower blood pressure could thus have substantial impact on population morbidity and mortality. Heart disease is the leading cause of death in the United States, accounting for over 765,000 deaths each year, and cerebrovascular disease, the third leading cause of death, accounts for 150,000 deaths each year. Hypertension is more common in blacks and the elderly. Efficacy of Screening Tests The most accurate devices for measuring blood pressure (e.g., intraarterial catheters) are not appropriate for routine screening because of their invasiveness, technical limitations, and cost. Office sphygmomanometry (the blood pressure cuff) remains the most appropriate screening test for hypertension in the asymptomatic population. Although this test is highly accurate when performed correctly, false-positive and false-negative results (i.e., recording a blood pressure that is not representative of the patient's mean blood pressure) do occur in clinical practice.3 A recent study found that 21% of persons diagnosed as mildly hypertensive based on office sphygmomanometry had no evidence of hypertension when 24-hour ambulatory recordings were obtained. Errors in measuring blood pressure may result from instrument, observer, and/or patient factors.5 Examples of instrument error include manometer dysfunction, pressure leaks, stethoscope defects, and bladders of incorrect width and length for the patient's arm size. The observer can introduce errors due to sensory impairment (difficulty hearing Korotkoff sounds or reading the manometer), inattention, inconsistency in recording Korotkoff sounds (e.g., Phase IV vs. Phase V), and subconscious bias (e.g., digit preference'' for numbers ending with zero or preconceived notions of normal'' pressures). The patient can be the source of misleading readings due to posture and biological factors. Posture (i.e., lying, standing, sitting) and arm position in relation to the heart can affect results by as much as 10 mm Hg.5 Biological factors include anxiety, meals, tobacco, temperature changes, exertion, and pain. Due to these limitations in the test-retest reliability of blood pressure measurement, it is commonly recommended that hypertension be diagnosed only after more than one elevated reading is obtained on each of three separate visits. Additional factors affect accuracy when performing sphygmomanometry on children; these difficulties are especially common when testing infants and toddlers under age 3.6 First, there is increased variation in arm circumference, requiring greater care in the selection of cuff sizes. Second, the examination is more frequently complicated by the anxiety and restlessness of the patient. Third, the disappearance of Korotkoff sounds (Phase V) is often difficult to hear in children and Phase IV values are often substituted. Fourth, erroneous Korotkoff sounds can be produced inadvertently by the pressure of the stethoscope diaphragm against the antecubital fossa. Finally, the definition of pediatric hypertension has itself been uncertain because of confusion over normal values during childhood. Previous criteria using population data to define the 95th percentile at different ages were erroneously high.7 Revised criteria for pediatric hypertension, based on data from over 70,000 children, have recently been published6 (see Clinical Intervention). Effectiveness of Early Detection There is a direct relationship between the magnitude of blood pressure elevation and the benefit of lowering pressure. In persons with malignant hypertension, the benefits of intervention are most dramatic; treatment increases five-year survival from near zero (data from historical controls) to 75%.8 The efficacy of treating moderate hypertension (diastolic blood pressure above 104 mm Hg) is also clear, as demonstrated in the Veterans Administration Cooperative Study on Antihypertensive Agents.9-11 In this randomized double-blind controlled trial, middle-aged men with diastolic blood pressure above 104 mm Hg experienced a significant reduction in cardiovascular events after treatment with antihypertensive medication. Persons with mild hypertension (diastolic blood pressure of 90-104 mm Hg) also benefit from treatment. This was confirmed in the Hypertension Detection and Follow-Up Program, a randomized controlled trial involving nearly 11,000 hypertensives.12 The intervention group received standardized pharmacologic treatment (stepped care'') while the control group was referred for community medical care. There was a statistically significant 17% reduction in five-year all-cause mortality in the group receiving standardized drug therapy; the subset with mild hypertension experienced a 20% reduction in mortality.12 Deaths due to cerebrovascular disease, ischemic heart disease, and other causes were also significantly reduced in the stepped care group.13 Similar results have been reported in other studies, such as the Australian National Blood Pressure Study14 and the Medical Research Council trial.15 Although treatment of hypertension is associated with multiple benefits, the greatest effect appears to be in the prevention of cerebrovascular disease.16 Improved treatment of high blood pressure has been credited with the greater than 50% reduction in age-adjusted stroke mortality that has been observed since 1972. Although the efficacy of antihypertensive treatment has been well established in clinical research, certain factors may influence the magnitude of benefit achieved in actual practice. First, the benefits of treatment may be less significant or less well proven in certain population groups, such as children. Second, nonpharmacologic first-line therapy (e.g., weight reduction, exercise, sodium restriction, decreased alcohol intake) may be less effective than drug therapy in achieving significant and consistent blood pressure reductions. Although it is known that weight reduction and sodium restriction can lower blood pressure,18,19 the magnitude and duration of reduction in actual practice may be limited by biological factors (e.g., hypertensives who are not salt-sensitive'') and the difficulties of maintaining behavioral changes (e.g., weight loss). Finally, compliance with drug therapy may be limited by the inconvenience, side effects, and cost of these agents. Recommendations of Others Revised recommendations for adults from the National Heart, Lung, and Blood Institute were issued recently by the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure,1 and similar recommendations have been issued by the American Heart Association.22 These call for routine blood pressure measurement at least once every two years for persons with a diastolic blood pressure below 85 mm Hg and a systolic pressure below 140 mm Hg. Measurements are recommended annually for persons with a diastolic blood pressure of 85-89 mm Hg. Persons with higher blood pressures require more frequent measurements. The Canadian Task Force recommends that all persons aged 25 and over receive a blood pressure measurement during any visit to a physician.23 The American Academy of Pediatrics and the National Heart, Lung, and Blood Institute recommend that children and adolescents receive annual blood pressure measurements from ages 3-20.6 Discussion It is clear from several large clinical trials that lowering blood pressure is beneficial and that the population incidence of several leading causes of death can be reduced through the detection and treatment of high blood pressure. An average diastolic blood pressure reduction of 6-8 mm Hg across the population could reduce the incidence of coronary artery disease by 25% and the incidence of strokes by 50%.24 At the same time, it is important for clinicians to minimize the potential harmful effects of detection and treatment. For example, if performed incorrectly, sphygmomanometry can produce misleading results. Some hypertensive patients thereby escape detection (false negatives) and some normotensive persons receive inappropriate labeling (false positives), which may have certain psychological, behavioral, and even financial consequences.25 Treatment of hypertension can also be harmful as a result of medical complications, especially related to drugs. Clinicians can minimize these effects by using proper technique when performing sphygmomanometry, making appropriate use of nonpharmacologic methods, and prescribing antihypertensive drugs with careful adherence to current guidelines. Clinical Intervention Blood pressure should be measured regularly in all persons aged 3 and above. The optimal interval for blood pressure screening has not been determined and is left to clinical discretion. Current expert opinion is that persons thought to be normotensive should receive blood pressure measurements at least once every two years if their last diastolic and systolic blood pressure readings were below 85 mm Hg and 140 mm Hg, respectively, and annually if the last diastolic blood pressure was 85-89 mm Hg.1 Sphygmomanometry should be performed in accordance with recommended technique.*1 Hypertension should not be diagnosed on the basis of a single measurement; elevated readings** should be confirmed on more than one reading at each of three separate visits. Once confirmed, patients should receive counseling regarding exercise (see Chapter 49), weight reduction, dietary sodium intake (Chapter 50), and alcohol consumption (Chapter 47).1 Other cardiovascular risk factors, such as smoking and elevated serum cholesterol, should also be discussed (Chapters 2 and 48). Antihypertensive drugs should be prescribed in accordance with recent guidelines1 and with attention to current techniques for improving compliance. Notes *Guidelines for Sphygmomanometry Patient should be seated with arm bared, supported, and positioned at heart level. Patient should have refrained from smoking or ingesting caffeine within 30 minutes before measurement. Measurement should begin after five minutes of quiet rest. An appropriate cuff size (child, adult, large adult) should be selected; the rubber bladder should encircle at least two thirds of the arm. Measurements should be taken with a mercury sphygmomanometer, a recently calibrated aneroid manometer, or a validated electronic device. Both systolic and diastolic pressures should be recorded; the disappearance of sound (Phase V) indicates the diastolic pressure. Two or more readings should be averaged; if the first two differ by more than 5 mm Hg, additional readings should be obtained. **In adults, current blood pressure criteria for the diagnosis are a diastolic pressure of 90 mm Hg or greater or a systolic pressure of 140 mm Hg or greater.1() In children, the criteria vary with age:6 Pediatric Blood Pressure Age (Yrs) Diastolic (mm Hg) Systolic (mm Hg) 0-2 74 112 3-5 76 116 6-9 78 122 10-12 82 126 13-15 86 136 References 1. 1988 Joint National Committee. The 1988 report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. Arch Intern Med 1988; 148:1023-38. 2. National Center for Health Statistics. Advance report of final mortality statistics, 1986. Monthly Vital Statistics Report [Suppl], vol. 37, no. 6. Hyattsville, Md.: Public Health Service, 1988. (Publication no. DHHS (PHS) 88-1120.) 3. Tifft CP. Are the days of the sphygmomanometer past? Arch Intern Med 1988; 148:518-9. 4. Pickering TG, James GD, Boddie C, et al. How common is white coat hypertension? JAMA 1988; 259:225-8. 5. Kirkendall WM, Feinleib M, Freis ED, et al. Recommendations for human blood pressure determination by sphygmomanometers. Subcommittee of the AHA Postgraduate Education Committee. Circulation 1980; 62:1146A-55A. 6. Task Force on Blood Pressure Control in Children. Report of the Second Task Force on Blood Pressure Control in Children--1987. Pediatrics 1987; 79:1-25. 7. Mehta SK. Pediatric hypertension: a challenge for pediatricians. Am J Dis Child 1987; 141:893-4. 8. Hansson L. Current and future strategies in the treatment of hypertension. Am J Cardiol 1988; 61:2C-7C. 9. Veterans Administration Cooperative Study Group on Antihypertensive Agents. Effects of treatment on morbidity in hypertension. III. Influence of age, diastolic pressure, and prior cardiovascular disease: further analysis of side effects. Circulation 1972; 45:991-1004. 10. Idem. Effects of treatment on morbidity in hypertension: results in patients with diastolic pressures averaging 115 through 129 mm Hg. JAMA 1967; 202:1028-34. 11. Idem. Effects of treatment on morbidity in hypertension. II. Results in patients with diastolic pressures averaging 90 through 114 mm Hg. JAMA 1970; 213:1143-52. 12. Hypertension Detection and Follow-Up Program Cooperative Group. Five-year findings of the Hypertension Detection and Follow-Up Program. I. Reduction in mortality of persons with high blood pressure, including mild hypertension. JAMA 1979; 242:Idem. Persistence of reduction in blood pressure and mortality of participants in the Hypertension Detection and Follow-Up Program. JAMA 1988; 259:2113-22. 14. Management Committee of the Australian National Blood Pressure Study. The Australian therapeutic trial in mild hypertension. Lancet 1980; 1:1261-7. 15. Medical Research Council Working Party. MRC trial of treatment of mild hypertension: principal results. Br Med J 1985; 291:97-104. 16. MacMahon SW, Cutler JA, Furberg CD, et al. The effects of drug treatment for hypertension on morbidity and mortality from cardiovascular disease: a review of randomized, controlled trials. Prog Cardiovasc Dis [Suppl] 1986; 29:99-118. and the declining incidence of stroke. JAMA 1987; 258:214-7. 17. Garraway WM, Whisnant JP. The changing pattern of hypertension and the declining incidence of stroke. JAMA 1987; 258:214-7. 18. Nonpharmacological approaches to the control of high blood pressure. Final report of the Subcommittee on Nonpharmacological Therapy of the 1984 Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 1986; 8:444-67. 19. Stamler J, Stamler R. Intervention for the prevention and control of hypertension and atherosclerotic diseases: United States and international experience. Am J Med 1984; 76:13-36. 20. McClellan WM, Hall WD, Brogan D, et al. Continuity of care in hypertension: an important correlate of blood pressure control among aware hypertensives. Arch Intern Med 1988; 148:525-8. 21. National Institutes of Health. The physician's guide: improving adherence among hypertensive patients. Working Group on Health Education and High Blood Pressure Control. Bethesda, Md.: Department of Health and Human Services, 1987. 22. Grundy SM, Greenland P, Herd A, et al. Cardiovascular and risk factor evaluation of healthy American adults. A statement for physicians by an ad hoc committee appointed by the Steering Committee, American Heart Association. Circulation 1987; 75:1340A-62A. 23. Canadian Task Force on the Periodic Health Examination. 1984 update. Can Med Assoc J 1984; 130:2-15. 24. Blackburn H. Public policy and dietary recommendations to reduce the population level of blood cholesterol. Am J Prev Med 1985; 1:3-11. 25. MacDonald LA, Sackett DL, Haynes RB, et al. Labelling in hypertension: a review of the behavioral and psychological consequences. J Chron Dis 1984; 37:933-42. .