CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 8, September 2012
AFRICA
461
general outpatient clinics), the use of FBPR as a single reading or
its inclusion in repeated readings for deriving average BP values
may not have a significant effect on clinical decisions regarding
BP classification or consideration for a diagnosis of hypertension;
(3)
in terms of clinically significant absolute differences (
≥
5
mmHg) between readings including and excluding FBPR,
differences between a purely hypertensive population and a
mixed population may not be of statistical significance. This
suggests that a recommendation for the exclusion of FBPR for
either of the population groups may not be clinically useful.
We observed that the issue of whether or not to discard the
FBPR is an important one that has not received adequate research
attention. Considering the fact that blood pressure measurement
is associated with transient discomfort to the patient, subjecting
patients to uncomfortable (albeit transient) cuff inflation and
deflation to obtain a reading that will be discarded without a
scientifically sound reason is unjustifiable. Discarding the FBPR
is associated with the expending of patient and personnel time
as well as energy. The consequence of this will be particularly
relevant in resource-poor settings.
Graves and Grossardt had earlier found that discarding the
first of three nurse-auscultatory or oscillometric blood pressure
measurements did not improve the association of office blood
pressure with ambulatory blood pressure readings.
11
Despite
conducting an extensive literature review, we were unable to
identify any previous study that addressed this issue with sets of
readings from the same BP monitor. However, it is noteworthy
to state that Mengden
et al
.
were the first to report that patients
are also inclined to discard the first reading in home monitoring
of blood pressure.
12
It is not unlikely that this practice may have
been acquired by the patients from physicians or nurses.
In our study, we focused on a single oscillometric device,
the BpTRU, because it was designed for automated exclusion
of the first BP reading. The value of this BpTRU design in
improving the association between OBP and ABPM has been
reported by Beckett and Godwin.
13
Their findings suggested that
by discarding the first reading, the improvement resulted from a
reduction in the white-coat effect. Therefore, while this device
may reduce the white-coat effect in comparative studies that
involved other devices with different principles and algorithms,
in our study, it has clearly been unable to justify the effect of
discarding the first reading on important parameters that often
guide hypertension-related clinical decisions.
We avoided the use of more than one device or additional
auscultatory measurements because of confounding factors that
could be introduced. Furthermore, it was considered that six BP
readings at one sitting were taxing enough for our participants.
Important limitations of our study include the relatively
small sample size. However, evaluation of our objectives in
sub-populations showed that findings within the final study
population were not likely due to chance.Also, these findings may
not necessarily apply to automated oscillometric measurements
in the home setting.
The strengths of this study lie in the wide range of blood
pressure values that were involved and the use of a general
out-patient population, which enabled us to perform sub-group
analyses of hypertensive and undifferentiated sub-populations.
There is a need for further studies with larger sample sizes to
create more robust evidence on this important clinical subject.
Also, investigation of the inclusion or exclusion of the first
blood pressure reading in HBPM will illuminate its effect on
the diagnosis and control of hypertension with the use of HBPM
readings.
Conclusion
Our findings suggest that exclusion of the first office BP reading
is not likely to have a significant impact on hypertension-related
clinical decisions.
This study was made possible through the research capacity developed from
the NIH grant R03TW007452-04. The authors are grateful to all participants
who willingly committed their time to this study.
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