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Cardiovascular Risk
Accuracy of a Home Blood Pressure Monitor Tested in
End-stage Renal Disease Patients
a report by
Aliza M Thompson, Kazuo Eguchi, Michael E Reznik, Samir S Shah and Thomas G Pickering
Department of Medicine, Behavioural Cardiovascular Health and Hypertension Program, and Division of Nephrology, Columbia University
Hypertension is a prevalent co-morbidity in the dialysis population. prior to their widespread use.
Monitoring blood pressure (BP) in the dialysis unit in order to identify
cardiovascular risk is common, but measurements taken in this setting have Using this protocol, a group of researchers tested one particular
been shown to be poor indicators of a patient’s BP control.
1
A convenient, device – the Microlife 3AC1-1PC – in a specific subpopulation: end-
portable device requiring minimal patient training that allows them to stage renal disease (ESRD) patients.
9
ESRD patients commonly suffer
accurately measure their own BP at home would dramatically improve care. from increased arterial stiffness,
10
which – as in other populations –
Several devices have come to market in an attempt to fill this niche, making could affect the accuracy of oscillometric BP devices used by these
use of oscillometric methods to replace the human ear and mercury patients. Thus, the researchers aimed to test the specific effect this
sphygmomanometers – the gold standard. These devices require manual condition had on differences in readings between the named
calibration and are known to be affected by patient characteristics. oscillometric monitor and the gold standard readings.
Studies to date have shown that oscillometric devices tend to Comparative Study
underestimate diastolic BP (DBP) and have been variably affected by Thompson et al. recruited 33 ESRD patients (24 male, nine female;
conditions such as diabetes and increased arterial stiffness with regard mean age 57 years) in total for the two phases of the study, following
to readings for systolic BP (SBP). Interestingly, previous studies that the protocol determined by ESH. All patients were on either
have shown such devices to underestimate DBP have also shown that
this effect was diminished in patients with diabetes or increased
arterial stiffness. For example, a retrospective analysis by van Ittersum
et al. of 106 insulin-dependent diabetics and 92 controls revealed that Monitoring blood pressure (BP) in the
DBP measurements in diabetics taken using the oscillometric device
dialysis unit in order to identify
were closer to the sphygmomanometric reading than were the
DBP measurements for controls.
2
The same study also found that SBP cardiovascular risk is common, but
was overestimated to a greater extent in diabetics compared with
measurements taken in this setting
healthy controls.
have been shown to be poor indicators
Other population-based cohort studies have demonstrated a
of a patient’s BP control.
relationship between arterial stiffness and the correspondence
between oscillometric home BP monitors and mercury sphygmo-
manometer readings.
3–4
Nevertheless, more widespread use of home BP monitoring has been haemodialysis or peritoneal dialysis (mean duration approximately two
recommended.
5–7
It is therefore important that potential purchasers years), and were under the care of physicians based at the New York-
are satisfied that such devices have been evaluated according to Presbyterian Hospital. Nearly two-thirds were diabetic. Those patients
agreed criteria, namely the European Society of Hypertension with sustained arrhythmia, severe tremors, lack of palpable pulse or
(ESH) International Protocol.
8
Furthermore, the accuracy of each history of arteriovenous fistula or graft on both upper arms, or those
oscillometric monitor should be confirmed in different subpopulations who were obese, were excluded.
The first phase of the study included 15 subjects with SBP between 90
Aliza M Thompson has recently completed a post-doctoral
research fellowship in nephrology in the Department of
and 180mmHg and DBP between 40 and 130mmHg. Between dialysis
Medicine at Columbia University, New York. She also sessions, nine sequential blood pressure measurements were taken
holds a Master degree in biostatistics from the same
from a non-fistula-bearing arm using both the Microlife oscillometric
institution. Dr Thompson received her medical degree from
Johns Hopkins Medical School and trained in internal
device (purchased for the study) and a standard mercury
medicine at New York-Presbyterian Hospital. Her
sphygmomanometer. Following these measurements, the researchers
reasearch interests include cardiovascular complications in
end-stage renal patients.
also assessed arterial stiffness using applanation tonometry on the
radial artery of the same arm. They took consecutive readings using the
E: at2026@columbia.edu
AtCor SphygmoCor device until three readings with a quality index
greater than 80% were obtained.
38 © TOUCH BRIEFINGS 2007