Canadian Medical Association Journal 1996; 155: 1693-1694
[résumé]
Paper reprints may be obtained from: Dr. William A. Whitelaw, Heritage Medical Research Building, University of Calgary, 3330 Hospital Dr. NW, Calgary AB T2N 4N1; wwhitela@acs.ucalgary.ca
© 1996 Canadian Medical Association (text and abstract/résumé)
Public and professional interest in sleep disorders is increasing rapidly in response to the growth of scientific knowledge about sleep physiology, the discovery of obstructive sleep apnea (and the subsequent development of an effective treatment) and the proliferation of medications for altering sleep. The vast numbers of patients eager to get help for such common complaints as snoring, insomnia, somnolence and fatigue place immense pressure on resources for diagnosis and treatment.
Polysomnography, the standard investigation for many sleep disorders, is expensive, costing approximately $1000 per patient. Waiting lists of many months and sometimes over a year are, unacceptably, the norm in many cities across Canada. Governments are puzzled as to how much of their health care budgets to allot to an area of practice with such potential to consume money and vulnerability to abuse. As a result, funding for sleep disorders medicine has lagged behind that for many other disciplines and is dealt with by each province differently. In Alberta, for example, neither diagnostic investigations such as polysomnography nor beneficial treatments such as continuous positive airway pressure to manage sleep apnea are funded; in Ontario, by contrast, funding for diagnosis and therapy is comprehensive and open ended.
Unfortunately, because evidence of the importance of most sleep disorders is still poorly defined, the need for diagnostic testing is not always clear. The funding priority given to a diagnostic procedure should rest on certain criteria. First, the test should perform well and be reproducible; this requires, among other things, a definition of the population in whom it will yield useful diagnostic information. Second, the problems that it diagnoses should have a significant impact on longevity or quality of life. Third, some benefit -- an effective treatment, helpful counselling or a useful prognosis -- should stem from a diagnosis. Sleep disturbances are not responsible for many deaths, but they can cause prolonged misery and impair energy and mental function. Controlled outcome trials are difficult to carry out and may in some cases be unethical. Validated measures of quality of life in patients with sleep disorders are still being developed. A high percentage of patients with severe sleep apnea or periodic leg movements, for example, get dramatically better with treatment and only then recognize how badly impaired they were before. Nevertheless, there are only loose correlations between mild to moderate physiologic disturbances as demonstrated by polysomnography and clinical signs and symptoms.[2] To provide evidence on which to found reasonable clinical decisions, we need to establish a favourable climate for excellence in clinical care and research. This would involve establishing a network of Canadian sleep centres for those purposes.
Given the huge demand for very limited diagnostic resources, the focus of recent research in Canada has been to determine whether some sleep disorders, especially sleep apnea, can be diagnosed and managed without polysomnography. Because the forecast for increased funding for polysomnography is unpromising, this hypothesis is a necessary and attractive one. It may be argued that the CSS/CTS standards should have made room for practitioners with less extensive training and experience to supervise testing for sleep apnea using simplified, home-based monitoring that relies mainly on oximetry. However, this argument is premature. Although many different types of monitors are in use, published evidence of their reliability is weak at best, coming from poorly designed trials with small samples. It can be expected that portable monitors and clinical approaches that can be used by general physicians to assess straightforward cases of sleep apnea will become established over the next few years, but standards for portable testing, including its indications, need to await the results of more extensive and rigorous clinical trials. In the meantime, patients will be much better served if testing, whether by full-scale polysomnography or by simple portable monitors, is supervised and interpreted by professionals whose training and experience allow them to fully appreciate the nuances of the clinical problems they are examining and the pitfalls of various assessment techniques.
Because polysomnography is expensive and likely to remain a limited resource, the strategy proposed by the CSS/CTS of using sleep disorders specialists as gatekeepers who decide whether testing is needed should also be supported. There is simply not enough evidence on which to base simple recommendations about indications for sleep disorders testing. Most patients with prevalent disorders such as obstructive sleep apnea and insomnia are separated from the rest of the population only by a degree. Who has not had some sleepless nights or felt unduly tired on some days? Most people who snore may have occasional apnea, especially after an evening of alcoholic revelling. Many other complaints are sometimes associated with a sleep disorder and could lead to a request to perform polysomnography; these include impotence, hypertension, headache, chronic fatigue, nephrotic syndrome, depression, fibromyalgia, snoring, bruxism, nightmares, anxiety attacks, chronic obstructive pulmonary disease, asthma, memory loss and restless legs. A wellness practitioner might want to check that the sleep of each patient is perfectly optimal. If polysomnography were as simple and cheap as electrocardiography -- that is, if it did not require the recording of 10 to 16 channels of electrical signals for 8 hours and did not demand expertise in the use of both electronic and cerebral software for its interpretation -- then perhaps everyone could undergo testing. As it stands, leaving some constraint on the number of tests performed and giving the responsibility for the wise use of this diagnostic resource to people who are knowledgeable and experienced in the field is a reasonable way to manage things while the evidence accumulates.
Sleep disorders medicine needs to find its proper place in the health care system. An important step is to establish credibility for its practitioners and diagnostic procedures. Following the CSS/CTS standards will go a long way toward assuring patients, physicians and payers that assessments performed in sleep laboratories are reliable and that the recommendations that stem from them are appropriate.