American Journal of Respiratory and Critical Care Medicine

Brief periods of breathing cessation (apneas) or marked reduction in Vt (hypopneas) are common in adults during sleep. Prospective studies indicate that sleep apnea contributes to systemic hypertension (1), is a modifiable risk factor for motor vehicle accidents (2), and that its adverse impact on quality of life is treatable (36). As a result, there is substantial and growing demand by patients to access diagnostic studies and effective treatment. Wait times result when demand exceeds capacity. Demand is influenced by (1) prevalence and incidence of sleep apnea, (2) cost and patient reimbursement policies, (3) patient and primary physician awareness, and (4) wait times. Capacity is dictated by (1) availability of sleep laboratory beds determined by funding policies, (2) adherence to guidelines for diagnosing sleep apnea and continuous positive airway pressure (CPAP) titration published by the American Academy of Sleep Medicine (7) and the American Thoracic Society (8), (3) availability of sleep specialists, and, (4) policies about who can order/interpret diagnostic polysomnography and CPAP titration studies. This article represents information from five countries regarding their population, annual number of sleep studies performed, the range of wait times patients experience, and some strategies used for dealing with the mismatch between demand and capacity (Table 1)

TABLE 1. Sleep study rates per 100,000 population and waiting time for diagnosis and treatment with continuous positive airway pressure in five countries



No. of Sleep

No. of Sleep

No. of Beds/

No. of Studies/yr

No. of Studies/yr/100,000

Waiting Time
United Kingdom58,800,000841700.325,00042.57–60
United States280,000,0001,2921,170,000427.02–10
. Policy issues regarding sleep laboratory funding and sleep specialist practice and training have also been addressed.

The authors have estimated data on number of sleep laboratories and studies and wait times because no country systematically tracks this.

United Kingdom

The population of the United Kingdom is 58.8 million ( It is estimated that there are 84 sleep laboratories in the United Kingdom with a total of 170 polysomnography beds (Simone De-Lacy, British Sleep Society, personal communication). The best estimate of the number of new patient sleep studies per year is 25,000 (42.5 studies per 100,000 population).

Waiting times vary widely across the country with no clear geographic trends. The average time for a nonurgent referral to be seen by a specialist is around 6 months (range, 2–24 months) and for a sleep study thereafter around 4 months (range, 0–48 months). Thereafter the delay for a CPAP titration is 4 months (range, 3–6 months). Thus, the overall wait from referral to CPAP averages approximately 14 months (range, 7–60 months).

The sleep center at the Edinburgh Royal Infirmary is university affiliated, but the funding for the clinical service is 100% from government. General practitioners refer half of the patients to this service and hospital specialists the other half. Sleep studies are ordered by one of two sleep physicians. To deal with the mismatch of demand and capacity, all referral letters are reviewed and prioritized by one of the sleep specialists. All patients living within 100 miles (160 km) are offered home-limited sleep studies, and only those with equivocal results get polysomnography. Patients living beyond 100 miles get split-night studies if their Epworth sleepiness score exceeds 11 (total score = 24) or if they report sleepiness when driving. Night nurses are cleared to start titrating CPAP if a sleepy patient's apnea–hypopnea index (AHI) exceeds 20 after 2 hours of good sleep.

These practices differ from those elsewhere in the United Kingdom. Overall, in the United Kingdom around two thirds of all “sleep studies” are oximetry alone and 20% are limited sleep studies, with only 10% being full polysomnography studies (Simone De-Lacy, British Sleep Society, personal communication). Over 50% of all such sleep studies are performed unattended at home. Oximetry alone studies are especially prevalent in England. Some general practitioners refer patients to otolaryngologists, who have no specific training in sleep, because of the long waiting times.

Reimbursement for diagnosis and treatment is provided completely from government. Almost all physicians who review patients with sleep apnea are respirologists. Training in sleep is unregulated, but at least 3 months in a sleep center is recommended for all trainee respiratory physicians.


Belgium has a population of 10.0 million and approximately 50 sleep laboratories. In 2001, about 17,700 adult polysomnographies were reimbursed by the social security system (177 studies per 100,000 population). More than 90% of polysomnographies were performed in hospital-based sleep laboratories.

A general practitioner may request a sleep study directly but most usually through referral to a sleep specialist of the particular hospital, usually a respirologist, neurologist, or adult psychiatrist. A standard, nonurgent referral will be seen within 1 to 3 weeks. Thereafter, the waiting time for diagnostic polysomnography varies from 2 weeks to 2 months, and the waiting time for a CPAP trial under polysomnography is generally 1 to 4 weeks. Thus, a patient who is nonurgent waits 1 to 3 months from referral to the start of therapy. Some laboratories add ambulatory equipment to standard hospital sleep beds to keep waiting lists within this range.

The sleep laboratory of the Cliniques Universitaires Saint-Luc, a 950-bed, private university hospital, receives referrals from general practitioners and specialists; after an outpatient assessment by a member of the medical team, a 24-hour hospital admission is ordered for testing that includes both afternoon and night polysomnography. To cope with increasing demand, we have increased the number days per week of operation from 4 nights to 7 nights (2 beds per night); we have not had to use portable monitoring or split-night studies. Clinical prediction rules are used to establish “a priori” probabilities but not to select patients.

Polysomnography in Belgium is reimbursed by a mandatory social security program if overseen by a specialist in neurology, psychiatry, respirology, or pediatrics, and it records standard signals. CPAP is covered if the AHI and the movement arousal index are at least 20 and 30, respectively, and the therapeutic polysomnography CPAP trial shows a clear improvement. Hospitals providing CPAP therapy have to be approved by a specific contract with the social security, thereby limiting the number of centers able to treat these patients.

Belgium has not defined the minimal requirements to read and interpret polysomnography; however, it is expected that physicians performing this task will be specialists with appropriate training.


Australia had a population of 18.97 million in 2001 ( An informal listing by Sleep Disorders Australia, a patient support group, has identified a total of 65 adult sleep laboratories across the country, with the number increasing each year. In a brief survey of these laboratories (60% response rate), 52% were in the private sector, 28% were in the public sector, and the remaining 20% had a mixture of public and private beds. There are a similar number of beds (∼ 122) in both the public and private sectors. The combined sectors are performing an estimated 53,500 polysomnograms per year (282 studies per 100,000 population). The real percentage of the population studied each year is likely to be only half of this figure as many studies represent treatment or follow-up studies.

Patients wait an average of 9 (range, 1–32) weeks for initial consultation after being referred. Sleep specialists request diagnostic polysomnography resulting in an additional wait of 21 (4–68) weeks in the public sector and 4 (112) weeks in the private sector. After completion of the diagnostic study, the time lapse until therapy is started is highly variable with some centers starting patients immediately and others waiting up to 40 weeks for a CPAP titration study. Most laboratories will prioritize studies on the basis of clinical urgency that is decided by the referring physician and some will also use clinical prediction rules. Some laboratories use split-night studies and some use oximetry studies to monitor moderate to severe cases who are started on CPAP. There are very few alternate diagnostic services (such as portable monitoring) provided by any of the sleep centers in Australia because of inadequate reimbursement. Some patients approach equipment companies directly for a trial of treatment, but little information is available about their outcomes.

Australians are provided with a federal government–funded Medicare system and state government–funded public hospitals. Sleep centers that operate in state government hospitals do not charge a polysomnography fee to the patient. Private sleep laboratories are reimbursed Australian $450 for polysomnography by Medicare; an additional Australian $350 to 500 is paid by the private health insurance fund and the patient in varying combinations. To access Medicare funding a “qualified sleep medicine practitioner” must be a Fellow of the Royal Australasian College of Physicians, necessitating postmedical degree training for 7 or more years, including a period of 1 to 3 years in full-time sleep medicine training. The Royal Australasian College of Physicians has recognized Sleep Medicine as a subspeciality of internal medicine and offers postgraduate training.

United States

The United States has an estimated population of 280 million (Central Intelligence Agency—The World Factbook 2002). A nationwide survey in June 2001 estimated that there were 1,292 sleep laboratories in the United States and that 1.17 million polysomnograms were performed in the preceding year (427 polysomnograms/100,000 population) (9). By contacting all known sleep laboratories in Massachusetts (34), Oregon (20), and Louisiana (29), this survey found polysomnography rates (studies per year per 100,000 population) of 529, 448, and 406, respectively. Estimates of rates in other states ranged from 121 (Colorado) to 1,161 (Maryland).

The Veterans Health Administration (VHA) provides additional insights concerning patient access to the diagnosis and treatment of sleep apnea in the United States. The VHA cares for approximately 3.75 million veterans (95% men, 5% women), and in 2001 there were 55 sleep laboratories in the VHA system (148 beds; 6,000 patients—160 studies per 100,000).

The average time from patient referral to sleep clinic evaluation and laboratory testing in the United States is quite variable ranging from a few weeks to more than a year. In general, wait times are longer in laboratories located in university, state, and federal government (VHA) facilities.

The Penn Sleep Center (University of Pennsylvania) receives patient referrals primarily from primary care providers within the medical center and throughout the greater Philadelphia area. Patients are scheduled for in-laboratory testing (12 beds) after clinic evaluation by sleep center specialists. The wait time from referral to initial clinic visit varies (2–12 weeks); the average time from clinic visit to polysomnogram is 2 to 3 weeks, although it was 4 to 5 months when the sleep laboratory capacity was four beds. Split-night studies are performed, but portable monitors are rarely used.

In contrast, the four-bed sleep center at the Philadelphia Veterans Affairs Medical Center, the only VHA sleep laboratory in the region, receives referrals from VHA providers in the states of Delaware, southern New Jersey, and eastern Pennsylvania. Funding for technology staff is only available to operate two beds, 4 nights per week. The average wait time from referral to initial clinic visit is 2 to 3 months and from clinic visit to polysomnogram an additional 2 to 3 months. Other VHA sleep programs report that patients wait on average approximately 8 to 9 months from laboratory referral to sleep evaluation. Using VHA guidelines, the Philadelphia Veterans Affairs Medical Center performs unattended home studies with validated portable monitors for diagnosis and to initiate treatment with CPAP in about 40% of patients with clinical suspected sleep apnea. When sleep apnea is diagnosed with a home study, a 1-week home auto-CPAP titration is performed before initiating CPAP treatment.

The majority of sleep evaluations are split-night polysomnograms, a practice driven by limited resources and reimbursement policies. Effective March 2, 2003, the Centers for Medicare and Medicaid Services accepts charges of US $807.69 for a split-night polysomnogram and US $223.62 for a Level II unattended sleep study (no sleep staging). Sleep laboratories such as those in the VHA and health maintenance organizations are more likely to perform sleep evaluations with portable monitors in addition to polysomnograms. The majority of sleep laboratories in the United States are directed by respirologists, and about one-third of them are accredited by the American Academy of Sleep Medicine. Certification of the sleep specialist and the sleep laboratory are increasingly being required for reimbursement by states and insurance carriers.


Canada has a population of 31.4 million (Statistics Canada: residents living in 10 provinces and 3 territories. The number of sleep studies per 100,000 varies greatly across the country (0–776 per 100,000, Table 2)

TABLE 2. Sleep study rates per 100,000 population across canada



No. of Sleep Labs

No. of Sleep Beds

No. of Beds/100,000

No. of Studies/yr

No. Studies/yr/100,000
Western Canada9,417,51415440.511,450122
British Columbia4,141,2725180.46,000145
Central Canada19,523,50981384*2.0*103,600*531*
Eastern Canada2,372,9254110.51,30055
Nova Scotia944,765260.670074
New Brunswick756,652130.445060
Prince Edward Island139,913000.000
Northwest Territories41,403000.000

*Data from all provinces obtained from questionnaires/telephone survey. Sleep laboratory contact list from personal communications and the Canadian Sleep Society ( All sleep laboratories were surveyed except Ontario, where numbers are based on projections generated from data provided by 38 of 69 known sleep laboratories.

as do waiting times. In eastern and western Canada the wait for sleep specialist consultation averages 4 to 6 months (in some places it exceeds 12 months), and completion of a polysomnogram varies from 8 to 30 months, resulting in a total wait of approximately 24 months (range, 8–36 months). Patients in Quebec experience similar wait times as the Western and Eastern regions. With greater sleep studies per capita in Ontario, wait times are much shorter for consultation and polysomnography, averaging 2.4 and 2 months, respectively, and there is generally little time required to start CPAP.

The sleep laboratory at the Foothills Medical Centre is affiliated with the University of Calgary, has four beds, and performs approximately 1,000 polysomnograms per year. Funding, including interpretation fees, is provided by the Calgary Health Region from its global operating funds provided by the provincial government. Physician consultation fees originate from a separate, fee-for-service budget. Patients are referred mostly by primary care physicians, some otolaryngologists, and some internists/subspecialists. Polysomnography ordering is limited to eight sleep consultants who review all referred patients. Split-night polysomnograms and home monitors (oximetry, body position, snoring, and airflow) (10) are used to increase capacity. Patients are triaged on the basis of medical history, a validated clinical prediction rule (11), and reported daytime sleepiness. Treatment is often initiated at home using auto-CPAP machines. Because of extensive wait times, primary care physicians have started to order home oximetry for their patients and will not necessarily refer these patients to the sleep center. This testing is not covered by provincial Medicare.

Provinces and territories have the responsibility of providing comprehensive medical coverage to their citizens. In most provinces funding is only available to hospitals for performing polysomnography, limiting the number of laboratories; however, in Ontario funding is available based on a fee for service contract that allows for nonhospital laboratories. CPAP funding varies across the country; in some provinces it is completely covered by provincial Medicare, although in the majority, patients are responsible for paying unless they have private insurance. The Royal College of Physicians and Surgeons of Canada has not recognized sleep medicine as a specialty. An increasing number of physicians who interpret polysomnography have been certified by the American Board of Sleep Medicine; however, this is not a stipulation of provincial licensing authorities for providing consultation and polysomnography interpretation services.

In many locations around the world patients suspected of having sleep apnea face challenges accessing diagnostic services and treatment because of the discrepancy between demand and capacity. Demand is difficult to quantify. The prevalence of sleep apnea, based on an AHI (number of apneas plus hypopneas per hour of sleep) of 5 or higher, is 24% in males (15.5%of whom self-report hypersomnolence; 4% have both) and 9% in females (22.3% of whom self-report hypersomnolence; 2% have both) aged 30 to 60 years (12). The prevalence of moderate sleep apnea (AHI ⩾ 15) is 9 and 4% in males and females, respectively. Sleep apnea is suspected in patients who are obese, hypertensive, habitual snorers, and hypersomnolent (13). All of these conditions are highly prevalent; thus a conservative estimate of the “at-risk” population who might be expected to be referred for assessment is at least twice the prevalence (13%) of moderate sleep apnea. Predictions of at-risk populations in this report have not been adjusted for age less than 30 and greater than 60 because the data is preliminary; it is estimated that about 2% of children have sleep apnea (14), but there is a high at-risk population of children who habitually snore (15) that is difficult to quantify. Sleep apnea prevalence is increased in older adults (15), which would offset possible lower rates in children.

Estimation of sleep apnea incidence is problematic because of using AHI cut points to identify who is at risk for incident sleep apnea at baseline. It is recommended to estimate incidence on the basis of the difference in prevalence between baseline and follow-up (T. B. Young, personal communication). Using this approach the incidence of moderate to severe sleep apnea (AHI ⩾ 15) is estimated at 0.6% (increase in prevalence of 5.1% over 8 years) (16).

The capacity for performing polysomnography is limited. The American Academy of Sleep Medicine recommends polysomnography for determining the severity of, and evaluating patients' response to treatment for, sleep apnea (7). The American Thoracic Society recommends polysomnography for CPAP titration (8). If these guidelines are followed, on the basis of incidence estimates alone, 600 polysomnograms per 100,000 population per year would be required; however, the Wisconsin sleep cohort study has found that 82% of men and 93% of women with moderate to severe sleep apnea have not been diagnosed (17). The capacity required to deal with these undiagnosed cases, spread over a 10-year period (82% of 9% of the male population and 93% of 4% of the female population), would be an additional 555 polysomnograms per 100,000 population per year. This assumes that each patient would only require a single polysomnogram and does not take into account at-risk patients who should be offered polysomnography but who ultimately are not diagnosed with sleep apnea. Using a conservative estimate that 50% of polysomnograms would be positive for sleep apnea, approximately 2,310 polysomnograms per 100,000 people per year would be required to adequately address the demand for diagnosis and treatment of patients with suspected sleep apnea of at least moderate severity. This exceeds by a factor of 10 in most countries and a factor of 50 in the United Kingdom, the actual capacity for polysomnography. In sleep centers where specialists control access to polysomnography, their availability is likely to be more limiting than polysomnography. If a full-time specialist reviewed 1,500 new patients with suspected sleep apnea per year (6 patients per day), a community would require 1.4 full-time sleep specialists per 100,000 population. For the Calgary population (∼ 1,000,000), this would translate into 14 full-time sleep specialists. At the Foothills Medical Centre, eight part-time sleep specialists equate to about one full-time position. Hence, we service approximately 7% of the potential sleep apnea referral population.

Funding models clearly dictate availability of polysomnography as evidenced by the marked variation in the rate of sleep studies per year across Canada (Table 2). In most locales in Canada and many across the world, polysomnography availability is capped by administrative funding. Waiting times for consultation, diagnosis, and treatment in this type of system are excessive; the exception is Belgium, which, although has a similar ratio of sleep studies to population as other countries, does not have similar waiting times. This would suggest that the demand there is limited, perhaps because of underrecognition by primary care physicians. Excessive waits lead to polysomnography alternatives for diagnosis and CPAP titration, in some circumstances by practitioners with little or no training in sleep or respiratory medicine. There is a lack of evidence indicating that these alternative strategies offer comparable outcomes for patients.

Patient access to appropriate investigation and treatment for sleep apnea is clearly restricted. Resources in the five countries that are included in this report, including the estimated resources in the United States (9), are inadequate to deal with conservative estimates of demand based on known prevalence and incidence data. Because treatment of sleep apnea provides many benefits to patients and society, it is imperative that strategies be developed, and research evidence gathered to support them, that address the current demand–capacity chasm.

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Correspondence and requests for reprints should be addressed to W. Ward Flemons, M.D., University of Calgary & Foothills Medical Centre, 1403 29th Street N.W., Calgary, AB, T2N 2T9 Canada. E-mail:


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