Objective. The clinical diagnosis of hypertension is subject to misclassification, and this may be clinically important. This article calculates positive and negative predictive values for blood pressure measurement and assesses the frequency of clinically important blood pressure misclassification. Design, Setting, and Participants. A modeling study was carried out on 4763 adults in the National Health and Nutrition Examination Survey (NHANES) population. True treatment eligibility was determined by applying Joint National Committee (JNC) VII criteria to individuals in the study population. Each individual was also allocated a series of blood pressures incorporating an error term reflecting day-to-day measurement variation. Test positives are persons classified as needing treatment on the basis of the mean of 2 blood pressure measurements. Measurements and Main Results. Positive predictive values of a diagnosis of hypertension based on 2 measurements were calculated for each age-sex group. Low-risk false positives and highrisk false negatives were categorized as clinically important errors. Positive predictive values are high in persons older than age 65. In persons ages 16 to 34, the positive predictive value is 0.24 (95% confidence interval [CI]: 0.17–0.32) in men and 0.16 (95% CI: 0.06–0.26) in women. Persons younger than age 35 are almost always at low risk of cardiovascular disease, and therefore this misclassification is clinically important. Even with 24-hour ambulatory blood pressure measurement, positive predictive values in young adults are under 0.5. Conclusions. Blood pressure estimation is a poor diagnostic test in low-prevalence populations such as young adults. Estimation of blood pressure should be informed by prior estimation of cardiovascular risk.
National High Blood Pressure Education Program. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Pub. No. 98-4080. Bethesda, MD: National Institutes of Health; 1997.
2.
The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. NIH Pub. No. 03-5233. Bethesda, MD: National Institutes of Health, National Heart, Lung and Blood Institute, National High Blood Pressure Education Program; 2003.
3.
Mosca L, Appel LJ, Bengamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. J Am Coll Cardiol. 2004;43:900–921.
4.
American Academy of Family Physicians. F-J: recommendations for periodic health examinations. Available at: http://www.aafp.org/x24975.xml. Last accessed 29 January 2004.
5.
University of Texas at Austin, School of Nursing, Family Nurse Practitioner Program. Screening for Hypertension in Adults. Austin: University of Texas at Austin, School of Nursing; 2002. Available at: http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=3226&nbr=2452. Last accessed 1 February 2005.
6.
Knottnerus JA, ed. The Evidence Base of Clinical Diagnosis. London: BMJ Books; 2002.
7.
Rosner B, Polk BF. Predictive values of routine blood pressure measurements in screening for hypertension. Am J Epidemiol. 1983;117:429–442.
8.
Hypertension Detection and Follow-up Program Cooperative Group. Variability of blood pressure and the results of screening in the hypertension detection and follow-up program. J Chronic Dis1978;31:651–667.
9.
Wright JM, Musini VJ. Blood pressure variability: lessons learned from a systematic review. Poster presentation D20 at the 8th International Cochrane Colloquium; Cape Town, South Africa; October 2000. Further details obtained from a personal communication (e-mail) on 21 July 2003.
10.
NHANES 1999–2000 Data Release (June 2002). Available at: http://www.cdc.gov/nchs/about/major/nhanes/nhanes99_00.htm. Last accessed 8 January 2004.
11.
NHANES 1999–2000 Public Release Dataset Laboratory 13AM— Triglycerides and LDL-Cholesterol (September 2003). Available at: www.cdc.gov/nchs/data/nhanes/frequency/l13amdoc.pdf. Last accessed 1 February 2005.
12.
Perloff D, Grim C, Flack J, et al. Human blood pressure determination by sphygmomanometry. Circulation. 1993;88:2460–2469.
13.
Blood Pressure Section of the Physician's Examination (June 2002). MEC Examination. Available at: www.cdc.gov/nchs/data/nhanes/frequency/bpxdoc.pdf. Last accessed 1 February 2005.
14.
Anderson KA, Wilson PWF, Odell PM, Kannel WB. An updated coronary risk profile: a statement for health professionals. Circulation. 1991;83:356–362.
15.
Baker S, Priest P, Jackson R.Using thresholds based on risk of cardiovascular disease to target treatment for hypertension: modelling events averted and number treatedBr Med J2000;320: 680–685.
16.
Assessment and Management of Cardiovascular Risk New Zealand Guidelines Group (NZGG). Date published: 8 December 2003. Available at: http://www.nzgg.org.nz/guidelines/dsp_guideline_popup.cfm?guidelineCatID=32&guidelineID=35. Last accessed 11 March 2004.
17.
Barter P, Best P, Boyden A, et al. Lipid management guidelines— 2001. Med J Aust2001;175(Suppl):S57–S88.
18.
National Cholesterol Education Program (NCEP). Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation. 2002;106:3143–3421.
19.
Wood D, Durrington P, Poulter N, McInnes G, Rees A, Wray R, on behalf of the Societies. Joint British recommendations on prevention of coronary heart disease in clinical practice. Heart. 1998;80 (Suppl 2):S1–S29.
20.
McAlister FA, O'Connor AM, Wells G, Grover SA, Laupacis A.When should hypertension be treated? The different perspectives of Canadian family physicians and patients. Can Med Assoc J2000;163:403–408.
21.
Trewby PN, Reddy AV, Trewby CS, Ashton VJ, Brennan G, Inglis J.Are preventive drugs preventive enough? A study of patients' expectation of benefit from preventive drugs. Clin Med2002;2:527–533.
22.
Lewis DK, Barton S.Who decides when to start preventive treatment? A questionnaire survey to compare the views of different population subgroups. J Epidemiol Community Health. 2003;57:241–242.
23.
Gueyffier F, Boutitie F, Boissel JP, et al. Effect of antihypertensive drug treatment on cardiovascular outcomes in women and men: a meta-analysis of individual patient data from randomized, controlled trials. The INDANA Investigators. Ann Intern Med1997;126:761–767.
24.
Blood Pressure Lowering Treatment Trialist's Collaboration. Effects of different blood-pressure-lowering regimens on major cardiovascular events: results of prospectively-designed overviews of randomised trials. Lancet. 2003;362:1527–1535.
25.
Little P, Barnett J, Barnsley L, Marjoram J, Fitzgerald-Barron A, Mant D.Comparison of agreement between different measures of blood pressure in primary care and daytime ambulatory blood pressure. Br Med J2002;325:254–260.
26.
Brueren MM, van Limpt P, Schouten HJA, de Leeuw PW, van Ree JW. Is a series of blood pressure measurements by the general practitioner or the patient a reliable alternative to ambulatory blood pressure measurement? A study in general practice with reference to short-term and long-term between-visit variability. Am J Hypertens. 1997;10:879–885.
27.
Bakx JC, Netea RT, van den Hoogen HJM, et al. De invloed van een rustperiode op de bloeddruk [The influence of a rest period on blood pressure measurement]. Huisarts en Wetenschap. 1999;42:53–56.
28.
Reeves RA. Does this patient have hypertension? How to measure blood pressure. JAMA. 1995;273:1211–1218.
29.
Marshall T, Anantharachagan A, Choudhary K, Chue C, Kaur I.A randomised controlled trial of the effect of anticipation of a blood test on blood pressure. J Hum Hypertens. 2002;16:621–625.
30.
http://www.cdc.gov/nchs/datawh/statab/unpubd/mortabs/gmwk12_10.htm. Last accessed 11 February 2004.
31.
Pickering TG. How should we take blood pressure in clinical practice? The wider use of home and ambulatory monitoring should be encouraged. Br Med J2003;327:E150–E151.
32.
The assessment and management of cardiovascular risk evidence-based best practice guideline. New Zealand Guidelines Group (NZGG) December 2003. Available at: http://www.nzgg.org.nz/guidelines/dsp_guideline_popup.cfm?&guidelineID=35. Last accessed 23 February 2004.
33.
De Backer G, Ambrosioni E, Borch-Johnsen K, et al. European guidelines on cardiovascular disease prevention in clinical practice. Third Joint Task Force of European and Other Societies on Cardiovascular Disease Prevention in Clinical Practice. Eur Heart J2003;24:1601–1610.
34.
Marshall T, Rouse A.Resource implications and health benefits of primary prevention strategies for cardiovascular disease in people aged 30 to 74: mathematical modelling study. Br Med J2002;325:197–199.
