DiagnOSAS as a screeningstool for obstructive sleep apnea syndrome in the primary care setting

DiagnOSAS (Diagnosis - Obstructive Sleep Apnea Syndrome) focuses on patients
with unexplained daytime symptoms of tiredness and sleepiness with or without
observed breathing stops and suspected by the general practisoner of
obstructive sleep apnea syndrome (OSAS).

In obstructive sleep apnea syndrome, patients have accompanying symptoms and
also a positive sleep study A sleep study is considerd positive if the
apneu/hypopnea index is at least five, indicating that more than five breathing
events occur per hour of sleep. During these breathing events (apneas or
hyopneas), the blood oxygen content decreases to a point that the body emmits a
reaction to wake up in order to start breathing again. The patient is often not
aware of this.

This 'wake up reaction' disturbs the sleep pattern which prohibits the patient
to rest fully during the night. As a consequence, patients are sleepy during
the day, function worse in their work and have an increased risk of serious
accidents at work and / or in traffic. In recent years, it has also become
known that OSAS is associated with a strongly increased risk of cardiovascular
and vascular disorders, including hypertension, arrhythmias and the development
of a heart attack or stroke. In addition, there is an increased risk of
developing diabetes, malignancies and dementia. Timely diagnosis and treatment
of OSAS is of vital importance to prevent both short and long term health
damage.

Annually, over 40,000 patients are referred by their GP to a sleep center with
suspected OSAS. Here, they are evaluated by a (team of) medical specialist(s)
and undergo numerous tests of which the most important is the
poly(somno)graphy. During such a test, several sensors are attached to the
patient in order to measure various variables during the night. The polygraphy
is stressful for the patient, time-consuming and also associated with high
costs. Furthermore, the waiting lists to undergo a polygraphy is growing and
therefore the (suspected) patients suffer from their complaints longer than
necessary.

Recent figures show that only 50% of patients referred to a sleep center
actually suffers from OSAS. On the other hand, approximately 80% of patients
who suffer from OSAS did not initially present with fatique symptoms at their
GP visit. It is estimated that several hundred thousand Dutch people are not
aware that they have Obstructive Sleep Apnea but are exposed to the harmful
(health) effects on a daily basis.

A better pre-selection of patients is needed in order to refer patients with a
very high suspicion of have OSAS and at the same time not referring patients
with a very low probablity of having OSAS. An accessible, simple, reliable and
inexpensive screening tool is required for this. With DiagnOSAS we hope to meet
this need.

Previous studies suggest that OSAS can also be established with the aid of a
nocturnal saturation measurement (pulse-oximetry). The reliability of nocturnal
pulse-oximetry would be similar to that of polygraphy. Moreover, a recent study
among more than 4,000 Philips employees, suggests that the absence of OSAS can
be identified with reasonable reliabilty using a simple questionnaire.

DiagnOSAS combines the use of an (online) questionnaire with data obtained by
means of night-time pulse-oximetry. In the present study, the diagnostic
parameters of DiagnOSAS for determining OSAS will be examined and compared with
polygraphy as the gold standard. The ultimate aim is to develop DiagnOSAS into
a reliable screening tool for OSAS for the general practice.

By offering a screeningstool for OSAS in the first line (general
practitioners), it is expected that diagnosing OSAS becomes easier, faster,
cheaper, more efficient, patientfriendly, and is also accessible to a wider
audience.

By offering a screeningstool for OSAS in the first line (general
practitioners), it is expected that diagnosing OSAS becomes easier, faster,
cheaper, more efficient, patientfriendly, and is also accessible to a wider
audience.

The current study is an observational study on the diagnostic value of
DiagnOSAS for identifying obstructive sleep apnea syndrome in 150 subjects (>
18 years) with suspected obstructive sleep apnea syndrome (OSAS) who are
referred by their GP to a sleep center for further diagnostics (polygraphy).
The subjects will complete a brief online questionnaire (25 items). In
addition, the oxygen level in the blood is noninvasively recorded by a
nocturnal pulse-oximetry in the comfort of their own home. After this night,
the subjects undergo polygraphy, which is currently the standard diagnostics
for obstructive sleep apnea syndrome and also acts as a gold standard.

Burden and risk to study participants was held to a minimum. Burden for the
patient for the DiagnOSAS study implies that they have to spend a night at home
with a (comfortable) pulse-oximeter. Wearing a "watch" can be experienced as
stressful by the patient, but carries no expected adverse events. In addition,
the completion of a questionnaire (25 items) is required. The questionnaire is
soley a burden for time. There are no questions included which may cause
ethical concerns. The questionnaire has been used in previous research.
Finally, the patient will have to go to their GP twice more than otherwise
necessary for collection / delivery of the pulse oximeter. There are no
expected serious adverse events. There are no further expected risks to the
investigation.