Finally, the manuscript contained no discussion of adherence to the device. While patients undoubtedly activated the stimulators while monitored during the sleep studies they underwent during the trial, we do not know how often they actually turned them on when unmonitored at home. Only time and experience will tell whether the frequently reported adverse events interfere with adherence. Ultimately, the question is whether this therapy reduces not just AHI but the adverse cardiovascular and cognitive sequelae of untreated OSA. While this procedure seems akin to pacemaker implantation, a common intervention with which we have all become familiar, it is not clear that the risks of infection and the frequency of battery replacement will be similar. Larger and longer-term studies are needed to better elucidate these outcomes and determine if other side effects develop over time, potentially related to longitudinal effects of repetitive stimulation of the hypoglossal nerve with every breath, every night, for years.
Comparative cost analyses have yet to be done, but it is difficult to imagine how upper airway stimulation could possibly compete with PAP in regard to this metric. Costs will derive not just from the device but also the multiple extra physician visits to assess its appropriateness. There is the cost of the implantation itself, a sleep endoscopy to assess for concentric palatal collapse (which makes patients less favorable candidates), the pre-op surgical consultation, and follow-up surgical visits. Patients will also require an additional sleep study after implantation to see whether the device is effectively eliminating sleep-disordered breathing. One can only speculate about the benefits that might be achieved by devoting equivalent money and time to improving PAP adherence.
Putting these results into perspective
Even with the strikingly positive results from STAR, it is important to note that only two-thirds of patients saw AHI reductions by at least 50%. In contrast, PAP is able to reduce apneas to the normal range (AHI less than 5) in the majority of patients. With PAP still the safest, most effective, and best-studied therapy available, efforts may be better directed at promoting its regular use. What strategies does the evidence support? Ensuring that patients’ initial experiences with PAP are optimized may be key: one study found that adherence 3 days into therapy was predictive of PAP use at 1 month (Budhiraja et al. Sleep 2007;30[3]:320). Humidification of the airway and intensive cognitive-behavioral therapy interventions have also shown benefit (Weaver and Grunstein Proc Am Thorac Soc. 2008; 5[2]:173). While there is no convincing evidence that one particular mask is superior to another, our experience suggests that trying a variety of interfaces helps patients find one that facilitates better adherence.
Treatment options for OSA remain limited. Many current choices, including nasal expiratory positive airway pressure devices, oral appliances, and uvulopalatopharyngoplasty (UPPP), are less effective than CPAP. Few patients are willing to undergo more invasive surgeries such as maxillomandibular advancement and tracheostomy, despite their superior efficacy. With risks seemingly similar to those of UPPP while being effective for more severely affected patients than are typically referred for that surgery, the hypoglossal nerve stimulator occupies a unique niche among these therapies. For a highly selected, nonobese population with severe OSA or high cardiovascular risk who are unable to tolerate PAP therapy, the hypoglossal nerve stimulator may represent a leap forward in PAP alternatives with promising early data to support its use.
Dr. Tobias is a fellow in the section of Pulmonary, Critical Care, and Sleep Medicine; and Dr. Won is an Assistant Professor of Medicine in the section of Pulmonary, Critical Care, and Sleep Medicine and Medical Director of the Yale Sleep Center, Yale University School of Medicine, New Haven, Connecticut.