AASM Membership Sections Newsletter Issue #2
21
without significant co morbidity and with high
pretest probability of OSA. The broader applicabil-
ity of such results however is open to question – for
example in the widely referenced study by Mulgrew
et al, only 3% of over 2000 patients referred for an
evaluation met eligibility criteria for randomization
for HST. Advantages to HST are convenience, and
hence better patient acceptance, low barrier to de-
ployment and, lower cost. Disadvantages include data
loss – which could be as high as 18%, a large percent-
age of indeterminate study results, particularly when
deployed in large numbers, misdiagnosis – both false
positive and false negative (which could be as high
as 31% and 45% respectively), and finally, inability to
determine effects on sleep architecture, as well as di-
agnose co-morbid sleep conditions such as periodic
limb movement disorder (PLMD) and REM behav-
ioral sleep disorder. Important concerns regarding
HST have been raised which include the lack of large
outcome studies, lack of external validity, particularly
in a heterogenous population with a high burden of
co-morbid cardiac and pulmonary disease. The cost
effectiveness of a strategy that largely adopts HST
as a diagnostic modality has also been questioned.
In an integrated health economic analysis Pietzch
et al have shown that “because of the higher risk of
false-positive diagnosis, the immediate cost-savings
from choosing the less expensive, less specific test
are overwhelmed by the long-term costs of treating
the many false-positive diagnosis patients without
benefit” and recommended in lab sleep study testing
when available as the preferred diagnostic modality
even in terms of a cost-benefit paradigm. It is impor-
tant to be aware of the limitations and contraindica-
tions of HST and these are well laid out in the clinical
guidelines paper published in the Journal of Clinical
Sleep Medicine by the AASM Portable Monitor-
ing task force. The key elements include selecting
patients with high pretest probability and excluding
patients with moderate to severe pulmonary disease,
neuromuscular disease and congestive heart failure,
or when other sleep disorders are either suspected or
comorbid including insomnia, periodic limb move-
ments disorder, parasomnias or narcolepsy. Also,
there needs to be in place in the program the provi-
sion for trained sleep technologists to provide direct
education to the patient for the application of sen-
sors, as well as a quality program that includes inter-
scorer reliability to assure accurancy and reliability.
More recently HST has assumed center stage as
multiple private payors have mandated use of HST
for most patients with sleep apnea, and required a
pre-authorization to justify use of inlab polysomnog-
raphy. Many of these payors are also outsourcing this
entire program to a utilization management firm.
The elements involved in such a relationship include
review and implementation of authorization policies,
and coordination of sites of service for diagnostic
and CPAP setups. The trend clearly calls for most if
not all sleep centers to begin to incorporate HST as
part of their diagnostic strategy. Issues to consider
as one incorporates a HST strategy include selecting
the appropriate equipment, and outlining an appro-
priate triage and distribution plan, that includes an
appropriate chain of custody. There is a wide variety
of HST equipment now available and a recent paper
from the AASM, published in the Journal of Clinical
Sleep medicine, has done a great job in categoriz-
ing the different systems on the basis of a SCOPER
system, so as to enable a ready comparison of the
features across different systems. Factors, besides the
technological features, that need to be considered
would include costs, not only of the equipment itself,
but more importantly of the disposables, as well as
data management, and software integration with your
existing platform. The AASM has outlined an ac-
creditation process for existing sleep centers to gain
accredited status as a provider of HST.
In summary, there is an increasing need for sleep
physicians to become aware of and initiate HST in
Home Sleep Testing continued
Continued >>