A Multi-centre Study To Evaluate the auto-cuff Response During home vs Ambulatory bp Monitoring

In the management and diagnosis of hypertension, home blood pressure
measurement (HBPM) and ambulatory blood pressure measurement (ABPM) show better
reproducibility and correlation with target organ damage than clinical office
blood pressure (BP) readings. There are, however, no studies reporting in
detail about the predictive value of BP differences between HBPM and ABPM.
There is one study reporting about patients with a difference in BP between
ABPM and HBPM, suggesting that patients with an elevated HBPM compared with a
normal ABPM might be at increased risk of cardiovascular death. However, these
data are inconclusive and reliable data about the prevalence and associated
patient characteristics are lacking. We postulate that this phenomenon is a
variant of the white-coat effect, and that these patients are actually not at
increased risk despite an elevated HBPM, and thus need to BP follow-up only at
ABPM. Therefore, the current study aims to provide data about the prevalence,
predictive value and clinical relevance of this phenomenon, which we refer to
as the auto-cuff response because these patients seem to respond to placing the
BP cuff around their arms. The study also aims to provide information on the
demographic characteristics and cardiovascular risk factors associated with the
auto-cuff response.
Current HBPM devices do not allow for nocturnal BP readings. Recently, a HBPM
device which allows several nocturnal readings has been introduced. Therefore,
the current study also assesses the difference in BP between nocturnal HBPM and
ABPM readings in a subgroup of patients.

This study has two principal aims. The first aim is to establish the relation
between the auto-cuff response and target organ damage defined as difference
in microalbumin/creatinin ratio. The second aim is to assess the difference in
BP between nocturnal HBPM and ABPM readings (AMSTERDAM at Night substudy).

A multi-centre open label crossover study in which seven hospital visits are
planned. When a patient is referred to HBPM or ABPM, the doctor will briefly
inform the patient on the current study and contacts one of the investigators.
The investigators contact the patient and informs him or her about the nature
of the study. If a patient is deemed eligible and is interested in the study,
the patient information folder will be send. The investigator will then again
contact the patient within approximately one week to answer potential
questions. If patient is still willing to participate, an appointment will be
scheduled.for the first visit. In the first visit, which last approximately 30
minutes, patient will again be informed on the study and informed consent will
be signed if the patient is wiling to participate. Then a questionaire will be
taken, and length and weight are recorded. Subsequently the patient will be
informed on the HBPM, and three supervised measurement will be recorded (office
BP measurement). An appointment for the delivery of the urine sample will also
be made, which co-incdes with one of the next visits. Patients also recieve the
anxiety questoinaires. After a week of HBPM, patients return for visit two to
recieve instruction on the 24h measurement. Data of the first HBPM week will
also be retrieved from the memory, so it can be cleared an given back to the
patient for the next week of HBOM. If it is not possible to read out the
information another device will be given, and instructions ons HBPM will be
briefly repeated. This visit lasts approximately 25 minutes. After this visit
the patient starts the ABPM. In visit three the patient returns the ABPM
device, which lasts about 5 minutes. In the fourth and final visit the patient
returns the HBPM device, which also takes about 5 minutes.
Due to a shortage of ABPM devices it is not possible to let the patient keep
the ABPM device until returning the HBPM device.

The burden of this study consists of a total of four visits, totaling
approximately 65 minutes. The techniques used are a 24h ABPM, and HBPM.
Furthermore an anxious state and trait questionnaire (an adapted Dutch version
of the Spielberger State-Trait Anxiety Inventory (STAI) for state and a visual
analogue scale (VAS) and a Dutch short form of the state scale of the STAI)
will be taken. Length, weight, waist circumference and an office BP (OBP) will
be assessed. The other BP measurements will be performed at home, but patients
need to be informed and instructed how to appropriately use the home or
ambulatory BP devices, which will find place within the selected study centers.
Additionally, a morning urine sample will be collected.
These measurements are considered safe. Most discomfort is expected to arise
from the 24h measurement, in which some patients complain about waking up from
the inflating cuff. This might also account for the nocturnal HBPM readings,
although there will be performed only three readings for one night per HBPM
session.
During the study patients are not allowed to change their blood pressure
lowering medication. Therefore, there is a risk some patient will have an
elevated BP for a maximum period of four weeks during the study in which their
BP lowering regiment can not be changed. However, in most patients the BP is
already increased for a prolonged period, and prolonging that period with a few
more weeks is not expected to affect their prognosis. One exception is a
hypertensive crisis in which case the study is terminated.