Ambulatory blood pressure monitoring is an accepted method of blood pressure measurement in hypertension trials. It is more reproducible than office blood pressure, does not show a placebo effect, and excludes white-coat hypertensive people, therefore offering significant advantages over office-based measurement. Investigators are aware of these advantages, and the use of ambulatory monitoring in hypertension trials is increasing.
JamesGDPickeringTGYeeLSHarshfieldGARivaSLaraghJH: The reproducibility of average ambulatory, home and clinic pressures. Hypertension1988, 11:545–549.
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BruceNGShaperAGWalkerMWannametheeG: Observer bias in blood pressure studies. J Hypertens1988, 6:375–380.
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GouldBAMannSDaviesABAltmanDCRafteryEB: Does placebo lower blood pressure? Lancet1981, ii:1377–1381.
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Ocon-PujadasJMora-MaciaJ: White coat hypertension and related phenomena: A clinical approach. Drugs1993, 46 (suppl 2):95–102.
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BulpittCJ: Responders and non-responders to antihypertensive treatment. Drugs1988, 35 (suppl 6): 142–146.
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TendlerBEWhiteWB: Assessing hypertension management: The role of 24-hour blood pressure monitoring. Cleve Clin J Med1993, 60:278–283.
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SeverPSPoulterNRBulpittCJ: Double-blind crossover versus parallel groups in hypertension. Am Heart J1989, 117:735–739.
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RoseMMcMahonFG: Some problems with antihypertensive drug studies in the context of the new guidelines. Am J Hypertens1990, 3:151–155.
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Lund-JohansenPOmvikPWhiteWBDigranesDHellandOJordalO: Long-term haemodynamic effects of amlodipine at rest and during exercise in essential hypertension. Cardiology1992, 80 (suppl 1):37–45.
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TrazziSMuttiEFrattolaAImholzBParatiGManciaG: Reproducibility of non-invasive and intra-arterial blood pressure monitoring: Implications for studies on antihypertensive treatment. J Hypertens1991, 9:115–119. This study showed that an improvement in the overall reproducibility of blood pressure measurements could be attained with modest numbers of ambulatory readings; intra-arterial recordings did not enhance this improvement.
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WhiteWB: Ambulatory blood pressure and target organ involvement in hypertension. Clin Invest Med1991, 14:224–230.
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WhiteWBDeyHMSchulmanP: Assessment of the daily blood pressure load as a determinant of cardiac function in patients with mild to moderate hypertension. Am Heart J1989, 118:782–795.
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AsmarRGBruneiPCPannierBMLacolleyPJSafarME: Arterial distensibility and ambulatory blood pressure monitoring in essential hypertension. Am J Cardiol1988, 61:1066–1070.
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MingJShengLLZhangLGRenQDXueyanCFenZJ: Abnormal renal function in isolated systolic hypertension correlation with ambulatory blood pressure. Int J Cardiol1993, 41:69–75.
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ShimadaKKawamotoAMatsubayashiKOzawaT: Silent cerebrovascular disease in the elderly: Correlation with ambulatory pressure. Hypertension1990, 16:692–699. This well-conducted study revealed a correlation between ambulatory blood pressure and the presence of a cerebral lesion probably caused by hypertension on a magnetic resonance imaging scan. This is the only study of its type.
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PerloffDSokolowMCowanR: The prognostic value of ambulatory blood pressures. J Hypertens1991, 9 (suppl 1):S33–S40. This study examined the cardiovascular outcome of treated hypertensive patients whose blood pressure was studied once using ambulatory monitoring and related it to other risk factors. Ambulatory blood pressure as well as traditional risk factors were predictors of future cardiovascular events. This is a strong but certainly not conclusive piece of evidence for a link between ambulatory blood pressure and outcome.
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MuttiETrazziSOmboniSParatiGManciaG: Effect of placebo on 24-h non-invasive ambulatory blood pressure. J Hypertens1991, 9:361–364. This study of 27 hypertensive patients showed that the placebo effect is absent from overall 24 h blood pressure readings. Ambulatory blood pressure data, however, did show a small placebo effect during the first 8h of treatment.
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DupontAGvan der NiepenPSixRO: Placebo does not lower ambulatory blood pressure. Br J Clin Pharmacol1987, 24:106–109.
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BottiniPBCarrAARhoadesRBPrisantLM: Variability of indirect methods used to determine blood pressure. Arch Intern Med1992, 152:139–144.
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SassanoPChatellierGCorvolPMenardJ: Influence of observer's expectation on the placebo effect in blood pressure trials. Curr Ther Res1987, 41:305–312.
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McDonaldCJMazzucaSAMcCabeGP: How much of the placebo effect is really statistical regression? Stat Med1983, 2:417–427.
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O'BrienEO'MalleyKCoxJSantonA: Ambulatory blood pressure monitoring in the evaluation of drug efficacy. Am Heart J1991, 121:999–1006.
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HoegholmAKristensenKSMadsenHSvendsenTL: White coat hypertension diagnosed by 24-h ambulatory monitoring. Am J Hypertens1992, 5:64–70.
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GrinJMMcCabeEJWhiteWB: Management of hypertension after ambulatory blood pressure monitoring. Ann Intern Med1993, 118:833–837. This cross-sectional study examined why practitioners recommended ambulatory monitoring and assessed their use of the results and the possible relevance to patient care. Practitioners appeared to make good use of the technique within current recommendations.
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MyersMGReevesRA: White coat phenomenon in patients receiving antihypertensive therapy. Am J Hypertens1991, 4:844–849.
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WhiteWBSchulmanPMcCabeEJDeyHM: Average daily blood pressure not office blood pressure determines cardiac function in patients with hypertension. JAMA1989, 261:873–877. This is an important study that showed that patients who had office hypertension but whose ambulatory blood pressures were normal had levels of cardiac hypertrophy similar to those in normotensive but much lower than those in hypertensive individuals.
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WeberMACheungDGGraettingerWFLipsonJL: Characterization of antihypertensive therapy by whole-day blood pressure monitoring. JAMA1988, 259:3281–3285.
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ConwayJCoatsA: Value of ambulatory blood pressure monitoring in clinical pharmacologyJ Hypertens1989, 7 (suppl 3):S29–S32. This paper discusses the two key factors in clinical trials that are improved by ambulatory monitoring: (1) the reduction in sample size possible through the improvement in reproducibility and (2) the exclusion of white-coat hypertensive individuals.
29.
ManciaGOmboniSParatiGTrazziSMuttiE: Limited reproducibility of hourly blood pressure values obtained by ambulatory blood pressure monitoring: Implications for studies on antihypertensive drugs. J Hypertens1992, 10:1531–1535. Fifteen hypertensive patients were assessed on two occasions 4 weeks apart using ambulatory monitoring. Although the reproducibility of overall mean blood pressures was high, hourly reproducibility was less impressive.
30.
PalatiniPMorninoPCanaliCSantonastasoMDe VenutoGZanataG: Factors affecting ambulatory blood pressure reproducibility. Results of the HARVEST trial. Hypertension1994, 23:211–216. This is the largest study (508 people) of ambulatory blood pressure reproducibility and the factors influencing it. The reproducibility of ambulatory blood pressures was higher than that of office pressures, and, in addition, some of the variability visible in the measurements could be accounted for by the patients' reaction to the medical care environment and by changes in body weight.
31.
SilagyCAMcNeillJFarishSMcCloudPIMcGrathBP: Components of blood pressure variability in the elderly and effects on sample size calculations for clinical trials. Am J Hypertens1992, 5:449–458. Twenty-six elderly hypertensive patients were studied for 4 weeks using office and ambulatory techniques, after which an estimate of the effect of ambulatory monitoring on sample sizes in clinical trials was made. A modest reduction of sample size was noted, but the authors emphasized the advantages of crossover designs and increasing the number of patients studied.
32.
FotherbyMDPotterJF: Reproducibility of ambulatory and clinic blood pressure measurements in elderly hypertensive subjects. J Hypertens1993, 11:573–579.
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WhiteWB: Analysis of ambulatory blood pressure data in antihypertensive drug trials. J Hypertens1991, 9 (suppl 1):S27–S32.
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DicksonDHasfordJ: 24-hour blood pressure measurement in antihypertensive drug trials: Data requirements and methods of analysis. Stat Med1992, 11:2147–2158. The authors of this study discuss the possible limitations of the analysis of ambulatory data and suggest using the moving interval mean as a smoothing technique to be carried out on individual blood pressure profiles.
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NeutelJMSmithDHGRamCVSKaplanNMPapademetriouVFaganTC: Application of ambulatory blood pressure monitoring in differentiating between antihypertensive agents. JAMA1993, 94:181–187. This study demonstrated the power of ambulatory blood pressure recordings to show significant differences in the blood pressure-lowering efficacy of two agents when no difference is detected using office blood pressures. The antihypertensive effect of bisoprolol was found to be greater than that of atenolol using ambulatory monitoring.
36.
WheltonAMillerWEDunneBHaitHITresznewskyPN: Once-daily lisinopril compared with twice-daily captopril in the treatment of mild to moderate hypertension: Assessment of office and ambulatory blood pressure. J Clin Pharmacol1990, 30:1074–1080.
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LacourcièreYLefebvreJProvencherPPoirierL: Comparison of quinapril and atenolol as single drugs or in combination with hydrochlorothiazide in moderate to severe hypertensives, using automated ambulatory monitoring. Br J Clin Pharmacol1993, 35:121–127.
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PalatiniPRacioppaARauieGZaninottoMPenzoMPessinaA: Effect of timing of administration on the plasma ACE inhibitory activity and the antihypertensive effect of quinapril. Clin Pharmacol Ther1992, 52:378–383.
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LacourcièreYLefebvreJPoirierLArchambaultFArnottW: Treatment of ambulatory hypertensives with nebivolol or hydrochlorothiazide alone or in combination. Am J Hypertens1994, 7:137–145. This multifactorial-design trial, which used ambulatory blood pressure measurements taken before randomization, showed that both nebivolol and hydrochlorothiazide, alone and in combination, had a dose-related antihypertensive effect. The reduction in mean blood pressure was corroborated with falls in blood pressure load. This is the largest such trial to use ambulatory blood pressure criteria for qualification.
