© 2004 American Thoracic Society
Single-Night Titration of Oral Appliance Therapy for Obstructive Sleep ApneaA Step Forward?Department of Respiratory and Sleep Medicine St. George Hospital, University of New South Wales Kogarah, Australia While mandibular repositioning appliances have proven effective in, and are preferred by, a significant proportion of patients with obstructive sleep apnea (1, 2), their prescription in clinical practice is limited by the inability to accurately predict the therapeutic response for the individual patient. This has remained a key unresolved issue in the field, and potentially translates into less favorable patient outcomes and inefficient use of resources. In the current issue of the Journal (pp. 366–370), Tsai and coworkers (3) have attempted to address this deficiency by titrating an oral appliance using an innovative remote-controlled device during a single-night sleep study to predict therapeutic response. At a conceptual level, this novel approach represents an exciting development because it is analogous to single-night titration for nasal continuous positive airway pressure. This is an important step in the growing acceptance of oral appliance therapy as a mainstream treatment for obstructive sleep apnea. In the past, various methods have been proposed to predict treatment outcome with mandibular repositioning appliances for obstructive sleep apnea. Cephalometric, polysomnographic, physiologic, and anthropomorphic parameters, or a combination thereof, have been reported to be useful predictors of objective therapeutic response (4–8). For example, younger age, lower body mass index, smaller neck circumference, shorter soft palate, smaller oropharynx, and supine-dependent obstructive sleep apnea have been proposed to predict a favorable outcome (4–7). These approaches, however, have generally relied on retrospective data analysis, in small numbers of patients, and none have evaluated the proposed model prospectively to verify clinical utility. This ongoing deficiency has spawned the novel concept of titrating mandibular advancement during polysomnography, which was first reported by Raphaelson and coworkers (9) and Petelle and coworkers (10). Advancing this concept, Tsai and coworkers (3) formulated positive and negative predictive values for their prognostic instrument, a remotely controlled stepping motor "trial appliance," studied in 19 patients with mild to severe sleep apnea. The elimination of respiratory events and oxygen desaturations had positive and negative predictive values for treatment outcome of 90 and 89%, respectively, which is a clinically important result. By comparison, the pilot study by Petelle and coworkers involved titration using a hydraulically controlled appliance during polysomnography (10). They achieved a mean advancement of 12.6 mm during sleep without inducing arousal, resulting in a significant reduction in mean apnea–hypopnea index from 66.9 to 26.1 events per hour during the titration study. The utility of any prognostic tool is critically dependent on its accuracy. The single-night titration process performed by Tsai and coworkers resulted in high precision according to their primary definition of treatment success, namely, the combination of an absolute reduction in respiratory disturbance index to less than 15 events per hour, with a relative reduction of greater than 30% from baseline and an improvement in symptoms (3). Modifying this definition, however, was shown to reduce the sensitivity and specificity of the procedure. This, combined with the general lack of consensus among researchers and clinicians as to what constitutes a successful treatment outcome for oral appliance therapy, may impose a limitation on the generalizability of these findings. Another consideration relates to those patients who are partially responsive to treatment, and whether such categorical criteria for "success" will misclassify them. Apart from the potential to predict therapeutic response, as indicated in the study by Tsai and coworkers, the attractiveness of this approach includes the possibility of simultaneously determining the optimum therapeutic "dose" of advancement required to treat obstructive sleep apnea and the potential to initiate treatment more rapidly than the norm of some months, which might be particularly relevant in severe cases or where there is concern about the risk of driving safety related to excessive sleepiness. With respect to the dose issue, there is little consensus in the field on how this should be determined. The recent work, however, of Fleury and coworkers (11) clearly indicates the need to move away from the often-used approach of an arbitrarily determined fixed percentage of maximum advancement. The study by Tsai and coworkers supports the need to individualize titration, but surprisingly, they did not find a role for the single night titration procedure in the determination of the optimum dose of advancement (3). This contrasts with the study by Petelle and coworkers, who found that the efficacy of the final oral appliance set at the level of advancement determined on the titration night was similar to the outcome achieved on the titration night (10). On the issue of potentially more rapid initiation of treatment using the single-night titration approach, the studies by Tsai and coworkers (3) and Petelle and coworkers (10) do not address this possibility. There are some practical limitations with the single-night titration approach that warrant consideration. A difficulty in arriving at a "prescription" for oral appliance therapy using single-night titration alone is the high variability in patient tolerance and symptomatic response to the treatment. This was evident in the present study, where it was found that the degree of mandibular advancement during titration did not necessarily equate with that achieved with the final appliance. Issues relating to standardization of the titration process, access to and cost of equipment, level of technical expertise, and the cost–benefit of the approach will need to be addressed in future studies if general uptake into the clinical arena is to take place. Furthermore, the need for an additional overnight polysomnograph could impose a burden on already stretched sleep laboratory services (12). Notwithstanding these limitations, this early work on single-night titration of oral appliance therapy represents an important first step in resolving the clinically important problem of prediction of therapeutic response. Ultimately, it is hoped that a simpler methodology, not requiring expensive equipment or overnight polysomnography, will emerge. Furthermore, work is required to systematically evaluate titration protocols in general, in order to achieve an optimal process and outcome for patients who undergo oral appliance therapy for obstructive sleep apnea. FOOTNOTES Conflict of Interest Statement: P.A.C. is a medical advisor (since January 2004) to a new medical device company that is planning to commercialize an oral appliance for snoring and obstructive sleep apnea, and holds shares in the company; H.G. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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