Press Release Date: December 8, 1998
An expensive, all-night test considered the "gold standard" for diagnosing sleep apnea—an under-recognized, under-diagnosed and potentially life-threatening nighttime breathing disorder—still appears to have no rivals, according to a study by the Boston research center, MetaWorks, Inc., conducted on behalf of the U.S. Agency for Health Care Policy and Research (AHCPR). But the study also concluded that several less expensive and less time-consuming tests than the overnight, full channel polysomnography (full PSG) appear promising for accurately diagnosing sleep apnea—a condition estimated to affect more than 12 million people in the United States and Canada.
The study's conclusions are based on a systematic review of the best available evidence from published research. MetaWorks was aided in its research by its partners, the Sleep Disorders Centre of Metropolitan Toronto and Blue Cross-Blue Shield of Massachusetts.
The Sleep Apnea evidence report is the first in a new series of evidence reports and technology assessments sponsored by AHCPR to provide public- and private-sector organizations with comprehensive, science-based information on common, costly medical conditions and health care technologies. MetaWorks is one of 12 AHCPR Evidence-based Practice Centers in the United States and Canada under contract to review all the relevant literature on designated topics related to prevention, diagnosis, treatment and management of common diseases and clinical conditions, and where appropriate, use of alternative or complementary therapies, and technology assessments of specific medical procedures or health care technologies.
AHCPR Administrator, John M. Eisenberg, M.D., said, "This report marks an important step forward in AHCPR's program of providing health care decisionmakers with the evidence they need to improve quality of care. The report provides the evidence needed to make accurate diagnoses of sleep apnea—a poorly understood and often under-diagnosed problem."
Dr. Eisenberg said that AHCPR will disseminate the report to a broad array of health care-related organization, government health agencies and other interested groups in the United States and Canada.
MetaWorks' director, Susan D. Ross, M.D., said, "Since the purpose of harnessing the data in this way is to put them to work for decision-making, we are eager to see how the results actually will be used. We are also eager to see the data updated often in order to maintain the usefulness of the information."
Interest in less expensive methods of diagnosing sleep apnea is growing because of the high cost of testing large numbers of patients. Experts estimate that up to four percent of all middle-aged men and two percent of women the same age—more than the percentage of people who have asthma—have sleep apnea. Persons with this disorder usually experience tiredness, fatigue, irritability and difficulty concentrating. Worse still, they are more likely to fall asleep at inappropriate times and have a higher rate of vehicular crashes and work-related accidents than other people.
Sleep apnea also affects the cardiovascular system. It is associated with increased blood pressure, cardiac arrhythmias during sleep, and it may contribute to myocardial ischemia and even myocardial infarction in persons with underlying cardiovascular disease. MetaWorks' systematic literature review also found some evidence, in a relatively small number of patients, that a full PSG may not be necessary to diagnose sleep apnea. In addition, oximetry—measurement of the arterial blood's oxygen saturation—performed in a sleep laboratory, chest and abdominal respiratory movements, and airflow alone (partial channel polysomnography), may have sufficient sensitivity and specificity when used with persons suspected of having obstructive sleep apnea.
There is still insufficient evidence that any multi-channel portable device can be used reliably to diagnose sleep apnea in a home setting. Other approaches, used to aid in diagnosing sleep apnea, including neck circumference and other body measurements; ear, nose and throat and dental assessments; radiologic exams including computerized axial tomography and magnetic resonance imaging, remain controversial.
The conclusions about the accuracy of methods for diagnosing or screening for sleep apnea were based on 71 analyzable studies, involving 7,572 patients, published between 1980 to November 1, 1997. The draft report was peer-reviewed by American and Canadian experts representing consumer groups and health care professions including neurology, pulmonary/respiratory disease, dentistry, otolaryngology, epidemiology and nursing, and by the American Sleep Disorders Association, American Sleep Apnea Association and the American Academy of Neurology.
Select for a summary of Systematic Review of the Literature Regarding the Diagnosis of Sleep Apnea (AHCPR 99-E001). Hard copies are available from AHCPR Publications Clearinghouse (P.O. Box 8547, Silver Spring, MD 20907 (telephone within the U.S: 1-800-358-9295 and 410-381-3150 from outside the United States).
The full report will be posted on the National Library of Medicine's HSTAT database, which can be accessed through AHCPR's website under "Clinical Information," in late January, 1999. Also at that time, printed copies of the full report will become available from the AHCPR Publications Clearinghouse.
Forthcoming AHCPR evidence reports and technology assessments examine traumatic brain injury, pharmacotherapy for alcohol dependence, evaluation of abnormal cervical cytology, depression treatment with new drugs, treatment of attention deficit and hyperactivity disorder, treatment of acute sinusitis, testosterone suppression treatment for prostatic cancer and other topics. Recently assigned topics include management of acute chronic obstructive pulmonary disease, management of cancer pain, criteria for weaning from mechanical ventilation and management of chronic hypertension during pregnancy.
Note to Editors: For further details about the study, including the respective roles of MetaWorks and of its partner organizations, call: Matthew Bush, MetaWorks, (617) 368-3575, ext. 218; Dr. Jeffrey Lipsitz, Sleep Disorders Centre of Metropolitan Toronto (416) 785-1128, ext. 301; Sus an Leahy, Blue Cross-Blue Shield of Massachusetts (617) 832-4823.
For additional information, contact AHCPR Public Affairs: Karen Migdail, (301) 427-1855 (KMigdail@ahrq.gov).
Internet Citation:
Overnight Test Still Best for Diagnosing Sleep Apnea. Press Release, December 8, 1998. Agency for Health Care Policy and Research, Rockville, MD. http://www.ahrq.gov/news/press/apneapr.htm