Dear Healthcare Provider,
With the emergence of home sleep testing, there has been some confusion regarding the
indications for home sleep testing. This letter is an attempt to provide clarity on the use
of home sleep testing.
Patients should be pre-screened for sleep apnea before using any home sleep testing
program. It is important to use a validated screening tool. The Berlin questionnaire is
the most validated screening tool, but unfortunately it is not easy to use or score. I prefer
the Stop-Bang questionnaire (see attached) because it is extremely simple. If the patient
answers yes to any 3 of the questions – they are at high risk for sleep apnea.
Home sleep testing should only be used in patients who are at high risk for sleep apnea.
Anyone who screens positive to the Stop-Bang questionnaire is high risk. I use
the Watermark Ares home testing device which performs level 2 sleep studies. Level 2
studies measure indices of both sleep and breathing. These studies have proven to be
equivalent to laboratory testing for the assessment of sleep apnea. Most home testing
equipment performs level 3 sleep studies which only record indices of breathing. Level 3
studies are also appropriate for testing for sleep apnea. A positive level 3 study is
sufficient for the diagnosis of sleep apnea. However a negative level 3 study in a high
risk patient does not rule out sleep apnea and necessitates a laboratory study.
Home sleep testing is not appropriate for patients who are not at high risk for
obstructive sleep apnea. It is also contraindicated in circumstances in which the accuracy
of the testing equipment may be altered. The most common scenario that will decrease
the accuracy of a home sleep testing device is the use of nasal oxygen. This is because
nasal airflow is usually measured by monitoring nasal pressure changes at the nose. The
slightly positive pressure of nasal oxygen can alter the signal.
Continuous positive airway pressure (CPAP) is the preferred therapy for sleep apnea.
There are 2 big categories of CPAP: traditional fixed pressure CPAP machines and autotitrating
CPAP machines. These have been shown to be equivalent in the treatment of
obstructive sleep apnea in multiple clinical trials. They are both recognized as an
acceptable treatment for sleep apnea by the American Academy of Sleep Medicine.
Fixed pressure CPAP machines require a laboratory based sleep study to determine the
best pressure for treatment. Auto-titrating CPAP machines are equipped with a
microprocessor that constantly monitors the patient’s breathing. If an increase in airway
resistance is noted, CPAP pressure is slowly increased. Therapy with an auto-titrating
CPAP machine can be initiated in the home.
Cost and convenience are the two areas that differ greatly between laboratory and
home based testing and treatment. Home sleep testing is roughly one-fourth the cost
of laboratory testing. The use of an auto-titrating CPAP machine can eliminate the need
for a second sleep study.
In summary, it is no longer necessary to send your routine sleep apnea patients to a sleep
laboratory. High quality, more cost effective care can be provided in the comfort and
convenience of the home.
Please contact me if I can be of assistance in managing your patients.
Thomas P. Stern, M.D., M.S.
Pulmonary, Critical Care, and Sleep Medicine