C-Reactive Protein Levels and the Risk of Incident Cardiovascular and Cerebrovascular Events in Patients with Obstructive Sleep Apnea.

PURPOSE: Patients with obstructive sleep apnea (OSA) are at increased risk of cardiovascular and cerebrovascular disease (CVD) but it is unclear who are at greatest risk. We determined whether the inflammatory marker, C-reactive protein (CRP), could be a useful prognostic biomarker. METHODS: Adult patients referred for polysomnography (PSG) with OSA were studied. Serum CRP levels were measured using ELISA the morning after PSG. Validated CV events within 4 years of PSG were ascertained by linking to provincial research datasets. RESULTS: 155 patients with OSA (AHI ≥ 5/h) had CRP measured. Median age was 53 and median AHI was 21/h. 10 patients (7.1%) suffered at least one event, but rates varied substantially by CRP (0/35 patients in the lowest quartile, and 7/39 in the highest CRP quartile). In the unadjusted analysis, patients in the highest CRP quartile (≥ 2.38 mg/L) were significantly more likely to suffer an event (odds ratio = 9.72 (95% CI 2.43-38.84), p = 0.001). CRP continued to be a significant predictor after controlling for multiple confounders. OSA severity and desaturation were not significantly associated with prospective events. CONCLUSIONS: In this small preliminary study, OSA patients with an elevated CRP were significantly more likely to suffer a CVD event in the 4 years after PSG. Although these findings need to be confirmed in larger prospective cohorts, CRP may be useful in risk stratifying OSA patients to guide therapy or to identify patients that might be most appropriate for clinical trials of CVD prevention.

Initial use of portable monitoring versus polysomnography to confirm obstructive sleep apnea in symptomatic patients: an economic decision model.

BACKGROUND: When using portable (level III and level IV) studies to "rule in" obstructive sleep apnea (OSA) in symptomatic patients, the pre-test probability (P) needs to be sufficiently high to minimize patients with negative tests who require full polysomnography. METHODS: We used a theoretical decision analysis model to assess the pre-test probability above which it would be appropriate to use portable studies to rule in disease in symptomatic patients with suspected OSA. For the base case, we considered a symptomatically sleepy patient referred with a probability of OSA of P. We determined the lower threshold of P appropriate for a clinical algorithm based upon an initial ambulatory study compared to initial diagnosis with PSG by comparing costs using the PSG algorithm with a diagnostic algorithm involving initial assessment with a portable study. RESULTS: In our base case, the pre-test probability above which portable testing would be less costly than initial diagnostic PSG would be 0.47. When an initial split night study was compared to portable testing, the pre-test probability above which portable testing was more economically attractive was greater (0.68). Values of P, however, varied considerably depending on values of many variables, including costs of diagnostic testing and CPAP compliance. CONCLUSIONS: Using a decision model, we have developed a theoretical framework to ascertain the pre-test disease probability above which portable studies would be economically attractive as an initial test in the assessment of patients with suspected OSA.

Cost-effectiveness of continuous positive airway pressure therapy in patients with obstructive sleep apnea-hypopnea in British Columbia.

BACKGROUND: Obstructive sleep apnea-hypopnea (OSAH) is a common disorder characterized by recurrent collapse of the upper airway during sleep. Patients experience a reduced quality of life and an increased risk of motor vehicle crashes (MVCs). Continuous positive airway pressure (CPAP), which is the first-line therapy for OSAH, improves sleepiness, vigilance and quality of life. OBJECTIVE: To assess the cost-effectiveness of CPAP therapy versus no treatment for OSAH patients who are drivers. METHODS: A Markov decision analytical model with a five-year time horizon was used. The study population consisted of male and female patients, between 30 and 59 years of age, who were newly diagnosed with moderate to severe OSAH. The model evaluated the cost-effectiveness of CPAP therapy in reducing rates of MVCs and improving quality of life. Utility values were obtained from previously published studies. Rates of MVCs under the CPAP and no CPAP scenarios were calculated from Insurance Corporation of British Columbia data and a systematic review of published studies. MVCs, equipment and physician costs were obtained from the British Columbia Medical Association, published cost-of-illness studies and the price lists of established vendors of CPAP equipment in British Columbia. Findings were examined from the perspectives of a third-party payer and society. RESULTS: From the third-party payer perspective, CPAP therapy was more effective but more costly than no CPAP (incremental cost-effectiveness ratio [ICER] of $3,626 per quality-adjusted life year). From the societal perspective, the ICER was similar ($2,979 per quality-adjusted life year). The ICER was most dependent on preference elicitation method used to obtain utility values, varying almost sixfold under alternative assumptions from the base-case analysis. CONCLUSION: After considering costs and impact on quality of life, as well as the risk of MVCs in individuals with OSAH, CPAP therapy for OSAH patients is a highly efficient use of health care resources. Provincial governments who do not provide funding for CPAP therapy should reconsider.

Risk and severity of motor vehicle crashes in patients with obstructive sleep apnoea/hypopnoea.

BACKGROUND: Obstructive sleep apnoea/hypopnoea (OSAH) appears to be associated with an increased risk of motor vehicle crashes (MVCs). However, its impact on crash patterns, particularly the severity of crashes, has not been well described. A study was undertaken to determine whether OSAH severity influenced crash severity in patients referred for investigation of suspected sleep-disordered breathing. METHODS: Objective crash data (including the nature of crashes) for 783 patients with suspected OSAH for the 3 years prior to polysomnography were obtained from provincial insurance records and compared with data for 783 age- and sex-matched controls. The patient group was 71% male with a mean age of 50 years, a mean apnoea-hypopnoea index (AHI) of 22 events/h and a mean Epworth Sleepiness Scale score of 10. RESULTS: There were 375 crashes in the 3-year period, 252 in patients and 123 in controls. Compared with controls, patients with mild, moderate and severe OSAH had an increased rate of MVCs with relative risks of 2.6 (95% CI 1.7 to 3.9), 1.9 (95% CI 1.2 to 2.8) and 2.0 (95% CI 1.4 to 3.0), respectively. Patients with suspected OSAH and normal polysomnography (AHI 0-5) did not have an increased rate of MVC (relative risk 1.5 (95% CI 0.9 to 2.5), p = 0.21). When the impact of OSAH on MVC associated with personal injury was examined, patients with mild, moderate and severe OSAH had a substantially higher rate of MVCs than controls with relative risks of 4.8 (95% CI 1.8 to 12.4), 3.0 (95% CI 1.3 to 7.0) and 4.3 (95% CI 1.8 to 8.9), respectively, whereas patients without OSAH had similar crash rates to controls with a relative risk of 0.6 (95% CI 0.2 to 2.5). Very severe MVCs (head-on collisions or those involving pedestrians or cyclists) were rare, but 80% of these occurred in patients with OSAH (p = 0.06). CONCLUSION: Patients with OSAH have increased rates of MVCs, and disproportionately increased rates of MVCs are associated with personal injury.

The impact of obstructive sleep apnea and daytime sleepiness on work limitation.

BACKGROUND: Many patients with obstructive sleep apnea (OSA) participate in the work force. However, the impact of OSA and sleepiness on work performance is unclear. METHODS: To address this issue, we administered the Epworth Sleepiness Scale (ESS), the Work Limitations Questionnaire (WLQ), and an occupational survey to patients undergoing full-night polysomnography for the investigation of sleep-disordered breathing. Of 498 patients enrolled in the study, 428 (86.0%) completed the questionnaires. Their mean age+/-standard deviation (SD) was 49+/-12 years, mean body mass index (BMI) was 31+/-7 kg/m(2) mean apnea hypopnea index (AHI) was 21+/-22 events/h, and mean ESS score was 10+/-5. Subjects worked a mean of 39+/-18 h per week. The first 100 patients to complete the survey were followed up at two years. RESULTS: In the group as a whole, there was no significant relationship between severity of OSA and the four dimensions of work limitation. However, in blue-collar workers, significant differences were detected between patients with mild OSA (AHI 5-15/h) and those with severe OSA (AHI>30/h) with respect to time management (limited 23.1% of the time vs. 43.8%, p=0.05) and mental/personnel interactions (17.9% vs. 33.0%, p=0.05). In contrast, there were strong associations between subjective sleepiness (as assessed by the ESS) and three of the four scales of work limitation. That is, patients with an ESS of 5 had much less work limitation compared to those with an ESS 18 in terms of time management (19.7% vs. 38.6 %, p<0.001), mental-interpersonal relationships (15.5% vs. 36.0%, p<0.001) and work output (16.8% vs. 36.0%; p<0.001). Of the group followed up, 49 returned surveys and 33 who were using continuous positive airway pressure (CPAP) showed significant improvements between the initial and second follow-up in time management (26% vs. 9%, p=0.0005), mental-interpersonal relationships (16% vs. 11.0%, p=0.014) and work output (18% vs. 10%; p<0.009). CONCLUSION: We have demonstrated a clear relationship between excessive sleepiness and decreased work productivity in a population referred for suspected sleep-disordered breathing. Screening for sleepiness and sleep-disordered breathing in the workplace has the potential to identify a reversible cause of low work productivity.

Impact of continuous positive airway pressure therapy on blood pressure in patients with obstructive sleep apnea hypopnea: a meta-analysis of randomized controlled trials.

Patients with untreated obstructive sleep apnea hypopnea (OSAH) are predisposed to developing hypertension, and therapy with continuous positive airway pressure (CPAP) may reduce blood pressure (BP). The purpose of this study was to assess the impact of CPAP therapy on BP in patients with OSAH. We performed a comprehensive literature search up to July 2006 [Medline, PubMed, EMBASE, Cochrane Database of Systematic Reviews (CDSR), Cochrane controlled trials register (CCTR), and Database of Abstract and Reviews of Effect (DARE)] to identify clinical studies and systemic reviews that examined the impact of CPAP on BP. Studies were included if they (1) were randomized controlled trials with an appropriate control group, (2) included systolic and diastolic BP measurements before and after CPAP/control in patients with OSAH, and (3) contained adequate data to perform a meta-analysis. To calculate pooled results, studies were weighted by inverse variances, with either a fixed or a random effects model used depending on the presence of heterogeneity (assessed with Q test). Ten studies met our inclusion criteria (587 patients): three studies were crossover (149 patients) and seven were parallel in design. Seven studies (421 patients) used 24-h ambulatory BP and three used one-time measurements. Two studies were of patients with heart failure (41 patients). Overall, the effects of CPAP were modest and not statistically significant; CPAP (compared to control) reduced systolic BP (SBP) by 1.38 mmHg (95% CI: 3.6 to -0.88, p = 0.23) and diastolic BP (DBP) by 1.52 mmHg (CI: 3.1 to -0.07; p = 0.06). Six of the trials studied more severe OSAH (mean AHI > 30/h, 313 patients); in these six trials, CPAP reduced SBP by 3.03 mmHg (CI 6.7 to -0.61; p = 0.10) and DBP by 2.03 mmHg (CI: 4.1 to -0.002; p = 0.05). There was a trend for SBP reduction to be associated with CPAP compliance. In unselected patients with sleep apnea, CPAP has very modest effects on BP. However, we cannot exclude the possibility that certain subgroups of patients may have more robust responses-this may include patients with more severe OSAH or difficult-to-control hypertension. Future randomized controlled trials in this area should potentially concentrate on these subgroups of patients.

Efficacy and patient satisfaction with autoadjusting CPAP with variable expiratory pressure vs standard CPAP: a two-night randomized crossover trial.

Expiratory pressure relief (C-Flex) technology monitors the patient's airflow during expiration and reduces the pressure in response to the patient. Increased comfort levels associated with C-Flex therapy have potential to improve patient adherence to therapy. The purpose of this study was to assess the combination of autoadjusting CPAP (APAP) and C-Flex in terms of (1) treatment efficacy, and (2) patient preference when compared to standard CPAP. Fifteen patients who had previously undergone formal CPAP titration polysomnography were treated with either one night of the APAP with C-Flex or one night of conventional CPAP, in a crossover trial. Patient satisfaction levels were recorded using visual analog scales (VAS) on the morning after the study. Mean patient age was 50 +/- 12 years, body mass index (BMI) was 36 +/- 6 kg/m(2), baseline AHI was 53 +/- 31 events/h, and CPAP Pressure was 11 +/- 2 cm/H(2)O. APAP with C-Flex was as effective as CPAP, with no differences detected in sleep latency (17 +/- 5 vs 12.3 +/- 3 min, p = 0.4), or respiratory indices (AHI of 4.2 +/- 2 vs 2.4 +/- 0.7 events/h, p = 0.1). VAS scores (scale 0-10) indicated a trend towards increased patient satisfaction while using APAP with C-Flex (7.9 vs 7.2, p = 0.07). 10 patients expressed a preference for APAP with C-Flex (VAS, 0 to 10) over standard CPAP (total positive score of 68, mean score of 4.8 +/- 4.3). One patient expressed no preference. Four patients expressed a preference for CPAP (total positive score of 13, mean score of 0.9 +/- 1.9) (APAP with C-Flex vs standard CPAP, p < 0.01 paired t test). APAP with C-Flex eliminates sleep disordered breathing as effectively as standard CPAP. Patients indicated a preference for APAP with C-Flex suggesting a possible advantage in terms of patient adherence for this mode of treatment.

Reduced sleep efficiency in cervical spinal cord injury; association with abolished night time melatonin secretion.

STUDY DESIGN: Case-controlled preliminary observational study. OBJECTIVE: Melatonin is usually secreted only at night and may influence sleep. We previously found that complete cervical spinal cord injury (SCI) interrupts the neural pathway required for melatonin secretion. Thus, we investigated whether the absence of night time melatonin in cervical SCI leads to sleep disturbances. SETTING: General Clinical Research Center, Brigham and Women's Hospital, Boston, USA. METHODS: In an ancillary analysis of data collected in a prior study, we assessed the sleep patterns of three subjects with cervical SCI plus absence of nocturnal melatonin (SCI levels: C4A, C6A, C6/7A) and two control patients with thoracic SCI plus normal melatonin rhythms (SCI levels: T4A, T5A). We also compared those results to the sleep patterns of 10 healthy control subjects. RESULTS: The subjects with cervical SCI had significantly lower sleep efficiency (median 83%) than the control subjects with thoracic SCI (93%). The sleep efficiency of subjects with thoracic SCI was not different from that of healthy control subjects (94%). There was no difference in the proportion of the different sleep stages, although there was a significantly increased REM-onset latency in subjects with cervical SCI (220 min) as compared to subjects with thoracic SCI (34 min). The diminished sleep in cervical SCI was not associated with sleep apnea or medication use. CONCLUSION: We found that cervical SCI is associated with decreased sleep quality. A larger study is required to confirm these findings. If confirmed, the absence of night time melatonin in cervical SCI may help explain their sleep disturbances, raising the possibility that melatonin replacement therapy could help normalize sleep in this group.

Inhaled corticosteroids reduce the progression of airflow limitation in chronic obstructive pulmonary disease: a meta-analysis.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a syndrome of chronic progressive airflow limitation which occurs as a result of chronic inflammation of the airways and lung parenchyma. However, the role of inhaled corticosteroids in the treatment of COPD is controversial. We hypothesised that inhaled corticosteroids reduce the progression of airflow limitation in COPD. METHODS: A comprehensive literature search was conducted and data were analysed using random effects methodology. The effect of inhaled steroids on annual change in forced expiratory volume in 1 second (FEV1) was determined for all trials, for trials with high dose treatment regimens, and for trials in subjects with moderate to severe airflow limitation. RESULTS: Data from eight controlled clinical trials of > or =2 years were included (n=3715 subjects). Meta-analysis of all study data revealed that inhaled corticosteroids reduce the rate of FEV1 decline by 7.7 ml/year (95% confidence interval (CI) 1.3 to 14.2, p=0.02). Meta-analysis of studies with high dose regimens revealed a greater effect of 9.9 ml/year (95% CI 2.3 to 17.5, p=0.01) compared with the meta-analysis of all studies. CONCLUSIONS: Inhaled corticosteroid treatment for > or =2 years slows the rate of lung function decline in COPD. The effect observed with high dose regimens is greater than that with all regimens combined. These data suggest a potential role for inhaled corticosteroids in modifying the long term natural history of COPD.

Predictors of loud snoring in persons with spinal cord injury.

BACKGROUND: Predictors of loud snoring were examined in a cohort of 197 persons with chronic spinal cord injury (SCI) recruited by advertisement and from a Veterans Affairs Medical Center SCI Service. METHODS: Data were collected on age, marital status, antispasticity medications, duration of injury, level and completeness of injury, stature, and weight. Body mass index (BMI) was calculated for all participants. A health questionnaire was used to collect data on snoring and respiratory history. Habitual snorers were defined as those who reported loud snoring more than 1 night per week. RESULTS: The mean age (+/- SD) was 51.2 +/- 14.8 years, and 84 of 197 (42.6%) were habitual snorers. The most obese research subjects, regardless of antispasticity medication use, were more likely to report snoring, but the risk of snoring was greatest among subjects who were obese and used antispasticity medication. Subjects who used antispasticity medication and had a BMI above the median (> or = 25.3 kg/m2) had a 7-fold risk of reporting snoring compared with subjects below the median who did not use antispasticity medication (P = .001). The greatest risk occurred in those who used diazepam alone or baclofen and diazepam together and had a BMI at or above the median. Subjects who used these medications and had a BMI below the median did not have a significantly increased risk. Neurological motor completeness, level of injury, age, and years since injury were not significant predictors of snoring. CONCLUSION: Because snoring is a marker for obstructive sleep apnea (OSA), the data suggest that in obese individuals with SCI, the use of antispasticity medications may be a risk factor for OSA.

The art and science of continuous positive airway pressure therapy in obstructive sleep apnea.

Despite the high prevalence of obstructive sleep apnea (OSA) syndrome, no ideal therapy has emerged to date. Based on recent randomized trials, continuous positive airway pressure (CPAP) therapy is the treatment of choice. Although CPAP can prevent pharyngeal collapse in virtually all patients who choose to wear it, poor patient adherence with treatment limits its effectiveness. Although convincing data exist that treatment with CPAP can alleviate the neurocognitive sequelae of OSA, data on cardiovascular complications are more limited. Several recent reports support a lowering of nocturnal and daytime blood pressure with CPAP, but data on the prevention of myocardial infarction and cerebrovascular events are currently lacking. Patient adherence with CPAP can be improved with optimization of mask comfort, heated humidification, and intensive support and education. For those who remain poorly compliant, alternative therapies such as autotitrating devices and oral positive airway pressure can be considered. Further research into the basic mechanisms underlying OSA will be required for new therapeutic targets to develop.

Hypercapnia can induce arousal from sleep in the absence of altered respiratory mechanoreception.

Possible mechanisms of arousal from respiratory stimuli include changes in PO(2), PCO(2), central respiratory drive, or respiratory mechanoreceptor activity. We sought to determine whether hypercapnia alone could induce arousal from sleep in four subjects with high (>/= C3) neurologically complete spinal cord injuries while on constant positive pressure mechanical ventilation (hence, respiratory mechanoreceptor activity remained constant). Subjects were chronically hypocapnic (mean baseline PET(CO(2)) = 21 mm Hg; range, 13-30 mm Hg). On the first night, the baseline rate of spontaneous awakenings was determined by polysomnography. On night two, FI(CO(2)) was increased rapidly in stable NREM sleep. Awakenings occurred in 19 of 19 trials within 5 min, with each subject waking and complaining of shortness of breath (mean time to arousal, 115 s; range, 26-264 s). It is unlikely that these were spontaneous, as the times to awakening during hypercapnia were much higher than during baseline conditions (p < 0.05). During rapidly induced hypercapnia, PET(CO(2)) overestimates the PCO(2) at the central chemoreceptors. To determine more precisely the PET(CO(2)) arousal threshold, PET(CO(2)) was increased slowly (approximately 2 mm Hg/min); arousal occurred at a mean PET(CO(2)) of 37 mm Hg (range, 23-45 mm Hg; mean change from baseline, 15.8 mm Hg, range, 10-20 mm Hg). Hence, both rapid and slow increases in PET(CO(2)) can induce arousal in humans in the absence of changes in respiratory mechanoreceptor activity.

Absence of detectable melatonin and preservation of cortisol and thyrotropin rhythms in tetraplegia.

The human circadian timing system regulates the temporal organization of several endocrine functions, including the production of melatonin (via a neural pathway that includes the spinal cord), TSH, and cortisol. In traumatic spinal cord injury, afferent and efferent circuits that influence the basal production of these hormones may be disrupted. We studied five subjects with chronic spinal cord injury (three tetraplegic and two paraplegic, all neurologically complete injuries) under stringent conditions in which the underlying circadian rhythmicity of these hormones could be examined. Melatonin production was absent in the three tetraplegic subjects with injury to their lower cervical spinal cord and was of normal amplitude and timing in the two paraplegic subjects with injury to their upper thoracic spinal cord. The amplitude and the timing of TSH and cortisol rhythms were robust in the paraplegics and in the tetraplegics. Our results indicate that neurologically complete cervical spinal injury results in the complete loss of pineal melatonin production and that neither the loss of melatonin nor the loss of spinal afferent information disrupts the rhythmicity of cortisol or TSH secretion.

Prevention of human diaphragm atrophy with short periods of electrical stimulation.

We determined whether prolonged complete inactivation of the human diaphragm results in atrophy and whether this could be prevented by brief periods of electrical phrenic nerve stimulation. We studied a subject with high spinal cord injury who required removal of his left phrenic nerve pacemaker (PNP) and the reinstitution of positive-pressure ventilation for 8 mo. During this time, the right phrenic nerve was stimulated 30 min per day. Thickness of each diaphragm (tdi) was determined by ultrasonography. Maximal tidal volume (VT) was measured during stimulation of each diaphragm separately. After left PNP reimplantation, VT and tdi were measured just before the resumption of electrical stimulation and serially for 33 wk. On the previously nonfunctioning side, there were substantial changes in VT (from 220 to 600 ml) and tdi (from 0.18 to 0.34 cm). On the side that had been stimulated, neither VT nor tdi changed appreciably (VT from 770 to 900 ml; tdi from 0.25 to 0.28 cm). We conclude that prolonged inactivation of the diaphragm causes atrophy which may be prevented by brief periods of daily phrenic nerve stimulation.

Breathlessness in spinal cord injury depends on injury level.

Little is known about the prevalence and predictors of breathlessness in individuals with neurologically complete chronic spinal cord injury (SCI). Between December 1992 and September 1993, we mailed a respiratory questionnaire to 1,147 community-based individuals with chronic SCI. The questionnaire included four questions about the presence of breathlessness during activities related to moving about. Of the 485 who replied (42 percent response rate), analysis was limited to adult males with neurologically complete motor injuries who reported using a hand-propelled wheelchair more than 50 percent of the time to get around. Of 130 subjects (33 tetraplegics, 53 high thoracic SCI, 44 lower injury levels), the patients with tetraplegia reported breathlessness more frequently (range for the four questions, 21-33%) than those with high thoracic (range, 9-15%) or lower injury levels (range, 2-11%). For each of the four questions there was a significant trend (p < 0.05) for subjects with higher levels of injury to report the greatest prevalence of breathlessness (tetraplegia > high thoracic > lower). The frequency of breathlessness was greatest in those with neurologically complete cervical injuries, an effect that was independent of obesity, smoking, age, and years since SCI. The mechanisms of breathlessness in SCI are unclear but elucidation might lead to strategies for providing relief.

Alternative therapies for sleep apnea.

Obstructive sleep apnea is characterized by the repetitive collapse of the upper airway during sleep. A variety of nonsurgical treatments for obstructive sleep apnea have been developed, including behavioral therapies, continuous positive airway pressure (CPAP) devices, oral appliances and medications. Presently, CPAP is considered the first-line treatment for moderate to severe sleep apnea and one of the first-line treatments for mild disease. However, the effectiveness of CPAP is compromised because a large proportion of patients cannot tolerate the devices. Oral appliances are one of the first-line therapies for mild sleep apnea and a treatment for more severe disease if CPAP cannot be tolerated. Medications have thus far been unsuccessful as a treatment option for sleep apnea. All patients should be counseled to avoid sleep deprivation and sedatives (including alcohol) and to lose weight if obese.

Oral appliances in the treatment of obstructive sleep apnea and snoring.

Treatment of snoring and obstructive sleep apnea with oral appliances is a promising alternative to continuous positive airway pressure (CPAP) therapy. Although there is wide variability in appliance design, these devices produce enlargement of the upper airway by advancing the mandible, tongue, or both. Oral appliances effectively reduce snoring in a significant proportion of individuals. In general they are less effective than CPAP in eliminating obstructive sleep apnea, with approximately 50% of individuals experiencing resolution of their obstructive sleep apnea with these devices. Patients with milder disease have greater success with oral appliance therapy than those with more severe disease. A small proportion of patients will experience worsening of their sleep apnea with an oral appliance, and close follow-up after device prescription is mandatory. Patient satisfaction with oral appliances may be better than that with CPAP.