Ambulatory Blood Pressure Monitoring to Assess the White‐Coat Effect in an Elderly East African Population

Abstract

5The authors hypothesized that published hypertension rates in Tanzania were influenced by the physiological response of individuals to blood pressure (BP) testing, known as the white-coat effect (WCE). To test this, a representative sample of 79 participants from a baseline cohort of 2322 people aged 70 years and older were followed to assess BP using conventional BP measurement (CBPM) and ambulatory BP monitoring (ABPM). There was a significant difference between daytime ABPM and CBPM for both systolic BP (mean difference 29.7 mm Hg) and diastolic BP (mean difference 7.4 mm Hg). Rates of hypertension were significantly lower when measured by 24-hour ABPM (55.7%) than by CBPM (78.4%). The WCE was observed in 54 participants (68.4%). The WCE was responsible for an increase in recorded BP. Accurate identification of individuals in need of antihypertensive medication is important if resources are to be used efficiently, especially in resource-poor settings. J Clin Hypertens (Greenwich). 2015;17:389-394. ª 2015 Wiley Periodicals, Inc.Globally, hypertension is a major cause of disability and early mortality.1-3 Previous reports of the prevalence of hypertension in sub-Saharan Africa (SSA) have indicated it to be at least as common as in many highincome regions.4,5 A recent study by members of our team revealed the prevalence of hypertension to be 69.9% in persons aged 70 years and older in rural Tanzania.6 Furthermore, few of those who had hypertension had been previously diagnosed, and effective hypertension control was rare.In most previously published studies of hypertension in SSA, conventional blood pressure measurement (CBPM) has been used to assess blood pressure (BP). However, the white-coat effect (WCE), first observed by Mancia and colleagues in 1983, 8 can lead to falsely elevated recorded BP values and mistaken diagnoses of hypertension, known as white-coat hypertension (WCH).9 WCH is thought to be present in 15% to 30% of people diagnosed with hypertension based on CBPM. 10The use of ambulatory BP monitoring (ABPM) can overcome many of the problems of CBPM. ABPM readings are normally taken over a 24-hour period, with the participant wearing a cuff and data recorded digitally. The use of ABPM is recommended by the National Institute for Health and Clinical Excellence in the United Kingdom for anyone with a CBPM ≥140/90 mm Hg. 11South African hypertension guidelines have been developed and recommend the use of ABPM in some situations.12 However, the impracticalities and cost of regular ABPM in resource-poor settings is acknowledged.Previous studies using ABPM to assess populations from SSA are few. Millen and colleagues 13 used ABPM to assess the relationship between BP, salt intake, and insulin resistance in a cohort of 331 patients from South Africa. In 2014, Polonia and colleagues 14 published a study comparing ABPM findings in untreated hypertensives living in Mozambique and Europe. Those in Mozambique were found to have higher BP, with a notably lower nighttime fall, than patients in Europe. Howev...

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“…In treated patients, the frequency of non-dipping pattern observed in the present study is higher than that of 43%, 53% and 61% found Ikama et al [11] in Brazzaville, Congo and Uys et al [12] in the North-West province, South Africa, respectively. It is, however, similar to that of 72.2% reported by Ivy et al [13] in 79 patients from South Africa of whom 26.6% were receiving antihypertensive medication.…”

Ambulatory Blood Pressure Monitoring to Assess Cardiovascular Risk in Sub‐Saharan Africa

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Ambulatory Blood Pressure Measurement Provides True and Prognostic Information on Blood Pressure Variability in Hypertensive Patients

“…We read the article "Ambulatory Blood Pressure Monitoring to Assess the White-Coat Effect in an Elderly East African Population" written by Ivy and colleagues 1 with great interest. They aimed to investigate the influence of the white-coat effect (WCE) on conventional blood pressure (BP) measurement (CBPM)-recorded hypertension rates in a cohort of elderly people living in rural Tanzania and found a significant difference between mean CBPM and ambulatory blood pressure monitoring (ABPM) readings in their study cohort.…”