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Explore This IssueMarch 2008
Experts agree that continuous positive airway pressure (CPAP) is the gold standard for management of obstructive sleep apnea. Although several types of surgical procedures have been used to treat obstructive sleep apnea (OSA), the evidence base for these procedures is suboptimal, explained Scott E. Brietzke, MD, Director of Pediatric Otolaryngology at Walter Reed Army Medical Center in Washington, DC, who moderated a miniseminar on evidence-based OSA at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery.
Diagnosis of OSA: Home Sleep Studies vs Laboratory Polysomnography
One hotly debated issue is use of lab versus home sleep studies for diagnosing obstructive sleep apnea. This is a timely topic. Medicare is currently debating whether to cover home sleep studies. The Institute of Medicine recognizes that 50 to 70 million Americans suffer from sleep disorders and there is a need for portable technology, stated M. Boyd Gillespie, MD, Associate Professor of Otolaryngology, Head and Neck Surgery and Director of the Medical University of Carolina Snoring Clinic in Charleston, SC.
The current standard for sleep assessment is laboratory polysomnography, which provides a high-quality sleep evaluation in a monitored setting. However, this type of test may not be widely available and is usually expensive. Alternatively, modified portable sleep apnea diagnostic devices that provide information on respiratory airflow and effort, heart rate, and oximetry are now available. These home sleep studies allow for the diagnosis of obstructive sleep apnea but cannot be used to diagnose less common disorders such as upper airway resistance syndrome or periodic limb movement disorder. Dr. Gillespie focused his remarks on modified portable sleep apnea testing versus polysomnography.
Home sleep studies are simple enough to use at home, and are more readily available and less costly than polysomnography. Further, home sleep studies are conducted in a natural sleep environment and analysis of the data is centralized, but there are concerns about accuracy with home sleep studies, Dr. Gillespie said. Sleep cannot be staged and respiratory disturbance index (RDI, used as a measure of sleep apnea) may underestimate the degree of apnea/hypopnea. It’s possible that a high rate of failed recordings can occur in an unattended setting [with home sleep studies], he noted.
A Medline search of available studies comparing home sleep studies and polysomnography yielded 14 randomized controlled trials with a total of 873 subjects. Eleven of the 14 studies found no difference in accuracy of identifying sleep apnea between home sleep studies versus polysomnography. In three of the studies, home sleep studies underestimated RDI compared with polysomnography.
In general, studies show agreement between attended and unattended home-based sleep studies and sleep-based lab polysomnography. Home sleep studies can be used more confidently in patients with a high pretest probability (>50%) of obstructive sleep apnea and therefore perform better in sleep apnea referral clinics than at-large community screenings, Dr. Gillespie said.
Studies are lacking comparing home sleep studies versus polysomnography for other important outcomes, such as clinical treatment decisions, and patient-based outcomes, such as morbidity and mortality, daytime sleepiness, and sleep-related quality of life, he said.
The true cost of sleep testing with either modality is difficult to calculate. Although home sleep studies are less costly to perform, unusable data are reported in 16% of tests, compared with 6% of polysomnography assessments. Home sleep studies may be less effective than polysomnography in maximizing patient outcomes. Therefore, the excess costs of polysomnography may be justified and are not excessive based on third-party willingness to pay, Dr. Gillespie told listeners.
CPAP is considered first-line therapy for obstructive sleep apnea, Dr. Brietzke said. Two extensive reviews by the Cochrane Collaboration have demonstrated the effectiveness of this modality. Subjective evaluations by patients treated with CPAP show a significant improvement in daytime sleepiness, but objective measurements are less robust in favor of CPAP, Dr. Brietzke stated.
However, CPAP works only if patients are compliant, and data show poor acceptance by patients. Studies show that 46% to 85% of patients use CPAP appropriately, he said. Efforts at improving compliance include autotitrating CPAP, biPAP, humidification, and education of patients. Studies comparing autoCPAP versus CPAP show a small effect in favor of autoCPAP, he said. Most patients prefer autoPAP because it delivers lower pressure. Studies of biPAP versus standard CPAP show no difference between these modalities, and more data are needed on the effectiveness of humidification. Studies suggest that education interventions and cognitive behavioral therapy can improve compliance.
Dr. Brietzke said that there is only indirect evidence to suggest that nasal surgery can improve CPAP tolerance. Three studies suggest that the combination of nasal surgery with hypopharyngeal surgery is associated with low complication rates and results in patient satisfaction. Dr. Brietzke said that although nasal surgery can reduce airway resistance, thereby lowering CPAP pressure requirement, it is unclear whether this results in improved compliance.
Nasal surgery alone does not improve the apnea/hypopnea index [AHI] and has success rates of 20 percent, he stated.
The database in support of uvulopalatopharyngoplasty (UPPP) was reviewed by Edward M. Weaver, MD, Associate Professor of Otolaryngology and Chief of Sleep Surgery at the University of Washington School of Medicine in Seattle.
Based on polysomnography results, overall success rates for UPPP is 40.7% in unselected patients. This is less than optimal, he noted. UPPP in selected patients improves polysomnography results, he continued.
Higher levels of evidence support variations of UPPP, he continued. One study showed that lateral PP was more successful in improving AHI and sleep parameters compared with UPPP (Cahali. Sleep 2004;27:942-50). A second study showed that transapalatal advancement was superior to UPPP for change in AHI (Woodson. Otolaryngol Head Neck Surg 2005;133:211-17).
There is consistent, but not overwhelming, evidence that UPPP improves survival compared with no treatment. In fact, UPPP improved survival more than CPAP did in studies that analyzed all their CPAP patients, including those who did not use it fully. There is favorable but less convincing evidence that UPPP improves cardiovascular risk and risk of motor vehicle accidents, Dr. Weaver told the audience.
Anatomical factors are predictive for success with UPPP, he continued. Patients with palatal obstruction have improved results compared with patients with tongue obstruction or mixed obstruction. Regarding palatal implants, Dr. Weaver said that there is conflicting evidence about whether palatal implants have any effect in patients with OSA. Palatal implants achieve a small reduction in AHI and a small worsening in apnea index (AI) in highly selected patients, he said. Palatal implants appear to improve polysomnography to a trivial degree, but they improve daytime sleepiness more significantly, he noted.
Hypopharyngeal surgery can be considered as a primary or secondary procedure if palatal surgery alone will not achieve the desired results, stated Eric Kezirian, MD, Director of the Division of Sleep Surgery in the Department of Otolaryngology-Head and Neck Surgery at the University of California, San Francisco School of Medicine.
Although several types of procedures are available-including tongue radiofrequency, genioglossus advancement, and maxillomandibular advancement-there is no single best procedure, according to the evidence. There are no randomized controlled trials to compare palatal surgery versus hypopharyngeal surgery, to compare palatal procedures alone versus combined palate and hypopharyngeal surgery, or to compare the different hypopharyngeal surgeries with sufficient numbers of patients. While certain procedures may provide better overall outcomes, evidence-based medicine suggests that these procedures do offer benefits in appropriate patients and that the selection among them must include a physician’s own surgical experience and patient preference, Dr. Kezirian said.
Hypopharyngeal surgery does not have a large number of randomized controlled trials. Therefore, we need to integrate the best evidence with clinical experience and patient preferences. It is difficult to perform randomized controlled trials because these are invasive procedures; blinding is difficult, and enrollment of a sufficient sample size will also be challenging, he stated. It is also unclear whether performing palatal and hypopharyngeal surgery at the same time or in separate procedures would be recommended. Risks may be higher when combining surgeries, but it is not known how this compares to adding the risks of two separate procedures, he stated.
©2008 The Triological Society