Effect of Weight Loss and Continuous Positive Airway Pressure on Obstructive Sleep Apnea and Metabolic Profile Stratified by Craniofacial Phenotype: A Randomized Clinical Trial.

Rationale: Craniofacial structure is believed to modulate the effect of weight loss on obstructive sleep apnea (OSA), but whether this affects metabolic profile after weight loss compared with continuous positive airway pressure (CPAP) is unknown among obese Chinese patients with OSA. Objectives: To compare the change in metabolic profile between a lifestyle modification program (LMP), stratified by craniofacial phenotype, and CPAP therapy for 6 months. Methods: We randomly assigned 194 patients with body mass index ⩾ 25 kg/m2 and moderate to severe OSA to participate in the LMP or receive CPAP therapy for 6 months in a 2:1 ratio. Assessments included computed tomography for assessing maxillomandibular volume (MMV), hsCRP (high-sensitivity C-reactive protein), and insulin sensitivity. Measurements and Main Results: Among 128 and 66 subjects in the LMP and CPAP groups, respectively, hsCRP was reduced more in the LMP group than the CPAP group (median [interquartile range], -0.7 [-1.4 to -0.0] vs. -0.3 [-0.9 to 0.4] mg/L; P = 0.012). More patients in the LMP group achieved low hsCRP (<1 mg/L) than the CPAP group (21.1% vs. 9.1%; P = 0.04). Insulin sensitivity improved only in the LMP group, with 3.1 (95% confidence interval, 1.5-6.6) times more patients with normal glucose regulation after intervention. The LMP group was stratified into LMP-small MMV (n = 64) and LMP-large MMV (n = 64) groups according to the median MMV value of 233.2 cm3. There was no significant difference in hsCRP (median [interquartile range], -0.7 [-1.3 to 0.1] vs. -0.7 [-1.5 to -0.2] mg/L; P = 0.884) and insulin sensitivity (median [interquartile range], 0.5 [-0.2 to 1.9] vs. 0.6 [0.1 to 2.0]; P = 0.4860) between the LMP-small MMV and LMP-large MMV groups. Conclusions: Weight reduction alleviated subclinical inflammation and improved insulin sensitivity more than CPAP among obese Chinese patients with moderate to severe OSA, and this effect was not influenced by craniofacial structure. Clinical trial registered with www.clinicaltrials.gov (NCT03287973).

Differences in respiratory arousal threshold in Caucasian and Chinese patients with obstructive sleep apnoea.

BACKGROUND AND OBJECTIVE: Ethnic differences in obstructive sleep apnoea (OSA) phenotype may not be limited to obesity and craniofacial factors. The aims of the study were to (i) compare the proportion of Caucasians and Chinese patients with a low respiratory arousal threshold (ArTH) and (ii) explore the influence of anatomical compromise on ArTH. METHODS: Interethnic comparison was conducted between cohorts of Caucasian and Chinese patients from specialist sleep disorder clinics. Polysomnography and craniofacial photography were performed. A low respiratory ArTH was determined by an ArTH score of 2 or above (one point for each: apnoea-hypopnoea index (AHI) < 30/h, nadir oxygen saturation (SaO2 ) > 82.5%, fractions of hypopnoeas > 58.3%). Anatomical compromise was stratified according to the photographic face width measurement. RESULTS: A total of 348 subjects (163 Caucasians and 185 Chinese) were analysed. There was a significantly lower proportion of Chinese patients with moderate-severe OSA (AHI ≥ 15) who had a low ArTH (28.4% vs 48.8%, P = 0.004). This difference remained significant among those with severe OSA (AHI ≥ 30) (2.6% vs 17.1%, P = 0.02). The proportion of moderate-severe OSA Caucasians with a low ArTH was significantly less in those with severe anatomical compromise (36.6% vs 61.0%, P = 0.03), whereas there was no difference in Chinese patients (25.5% vs 31.5%, P = 0.49). CONCLUSION: Compared to Caucasians with severe OSA, a low respiratory ArTh appears to be a less common pathophysiological mechanism in Chinese patients. Caucasians with less severe anatomical compromise exhibit evidence of a lower ArTh, an association which is absent in Chinese patients. Our data suggest that OSA mechanisms may vary across racial groups.

Craniofacial phenotyping for prediction of obstructive sleep apnoea in a Chinese population.

BACKGROUND AND OBJECTIVE: Craniofacial morphology is a risk factor for obstructive sleep apnoea (OSA). Facial photography has previously shown utility in predicting OSA in a Caucasian sleep clinic. However, ethnic differences in OSA risk factors may influence these facial predictors. Our aim was to assess phenotypical facial measurements for OSA prediction in a Chinese population. METHODS: Calibrated frontal and profile facial photographs were taken before polysomnography. Photographs were analysed to derive head, face and neck measurements. Demographical, anthropometrical and facial photographical variables were considered in prediction models for OSA. OSA prediction models were derived using logistic regression and classification and regression tree techniques. RESULTS: Two-hundred subjects were recruited (146 OSA, 54 controls). The OSA group contained more men (77% vs 61%) and were more obese. Logistic regression modelling found cervicomental angle (OR 1.06/degree, 95% CI: 1.03-1.09, P < 0.001) and face width (OR 1.7/cm, 95% CI: 1.1-2.7, P = 0.02) predicted OSA (area under the receiver operating characteristics curve 0.76). Classification and regression tree analysis identified cricomental space area, mandibular width, mandibular plane angle and neck soft tissue area as predictors (area under receiver operating characteristics curve 0.81). CONCLUSION: In a Hong Kong Chinese sleep clinic, facial photographical measurements had predictive utility for OSA. Prediction models had similar accuracy and included variables to a previous Caucasian population.

Obesity and craniofacial structure as risk factors for obstructive sleep apnoea: impact of ethnicity.

OSA is the result of structural and functional abnormalities that promote the repetitive collapse of the upper airway during sleep. This common disorder is estimated to occur in approximately 4% of men and 2% of women, with prevalence studies from North America, Australia, Europe and Asia indicating that occurrence is relatively similar across the globe. Anatomical factors, such as obesity and craniofacial morphology, are key determinants of the predisposition to airway collapse; however, their relative importance for OSA risk likely varies between ethnicities. Direct inter-ethnic studies comparing craniofacial phenotypes in OSA are limited. However, available data suggest that Asian OSA populations primarily display features of craniofacial skeletal restriction, African Americans display more obesity and enlarged upper airway soft tissues, while Caucasians show evidence of both bony and soft tissue abnormalities. Our recent comparison of Chinese and Caucasian OSA patients found for the same degree of OSA severity. Caucasians were more obese, and Chinese had more skeletal restriction. However, the ratio of obesity to craniofacial bony size (or anatomical balance, an important determinant of upper airway volume and OSA risk) was similar between Caucasians and Chinese OSA patients. Ethnicity appears to influence OSA craniofacial phenotype but furthermore the relative contribution of the anatomical factors underlying OSA risk. The skeletal restriction craniofacial phenotype may be particularly vulnerable to increasing obesity rates. Better understanding of craniofacial phenotypes encompassing ethnicity may help improve OSA recognition and treatment; however, further studies are needed to elucidate ethnic differences in OSA anatomical risk factors.

Effect of weight loss on upper airway size and facial fat in men with obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) is commonly associated with obesity and can be improved by weight loss. Changes in upper airway size related to regional fat loss may mediate the improvement in OSA. This study aimed to assess changes in upper airway size and regional facial and abdominal fat with weight loss and their association with OSA improvement. METHODS: Middle-aged obese men with moderate-to-severe OSA underwent a 24-week sibutramine-assisted weight loss trial. Polysomnography and CT of the head and neck were performed at baseline and 24 weeks. The upper airway lumen and facial and parapharyngeal fat were measured with image analysis software. RESULTS: Post-intervention there was a significant reduction in weight (-7.8±4.2 kg, p<0.001) and apnoea-hypopnoea index (AHI) (-15.9±20.5 events/h, p<0.001). Velopharyngeal airway volume significantly increased from baseline (5.3±0.4 to 6.3±0.3 cm(3), p<0.01) and facial and paraphayngeal fat volume significantly reduced. A reduction in upper airway length was associated with improvement in AHI (r=0.385, p=0.005). The variance in AHI improvement was best explained by changes in upper airway length and visceral abdominal fat (R(2)=0.31, p=0.004). CONCLUSIONS: Weight loss increases velopharyngeal airway volume, but changes in upper airway length appear to have a greater influence on the reduction in apnoea frequency. Inter-individual variability in the effects of weight loss on OSA severity cannot be explained in terms of changes in upper airway structure and local fat deposition alone.

Use of flow-volume curves to predict oral appliance treatment outcome in obstructive sleep apnea: a prospective validation study.

PURPOSE: Flow-volume curves have been shown to relate to upper airway physiology during sleep and may be useful for predicting the response to treatment of obstructive sleep apnea (OSA) with mandibular advancement splints (MAS). The aim of this study was to prospectively assess the potential clinical utility of a previously derived prediction method using flow-volume curves performed during wakefulness. METHODS: Patients with newly diagnosed OSA interested in undertaking treatment with a custom-made MAS were approached to participate in the study. Response to treatment was defined by a 50% or greater reduction in the apnea-hypopnea index. Flow-volume curves were performed in the erect position prior to construction of the MAS. RESULTS: Flow-volume curves were performed in 35 patients. Of these, 25 patients were responders, and 10 patients were non-responders. A combined cut-off of an inspiratory flow rate at 50% of vital capacity (MIF50) less than 6.0 L/s and a ratio of the expiratory flow rate at 50% of vital capacity to MIF50 of greater than 0.7 correctly classified 48.6% of the patients. It had a sensitivity of 36.0%, specificity of 80.0%, positive predictive value of 81.8%, and negative predictive value of 33.3%. CONCLUSIONS: These results suggest that the previously derived prediction model, using flow-volume curves performed during wakefulness, was not sufficient to reliably predict the response to treatment of OSA with MAS. A combination of a functional assessment using flow-volume curves and a structural evaluation of the upper airway with imaging modalities may result in a prediction model with better performance characteristics.

The effect of mandibular advancement on upper airway structure in obstructive sleep apnoea.

BACKGROUND: The mechanisms by which mandibular advancement splints (MAS) improve obstructive sleep apnoea (OSA) are not well understood. This study aimed to evaluate the mechanism of action of MAS by assessing their effect on upper airway structure in patients with OSA. METHODS: Patients were recruited from a sleep disorders clinic for treatment with a custom-made MAS. MRI of the upper airway was performed during wakefulness in the supine position, with and without the MAS. RESULTS: Sixty-nine patients with OSA were recruited. Treatment with the MAS reduced the apnoea-hypopnoea index (AHI) from 27.0+/-14.7 events/h to 12.2+/-12.5 events/h (p<0.001). There was an increase in the total airway volume with mandibular advancement (16.5+/-0.7 cm(3) vs 18.1+/-0.8 cm(3); p<0.01) that occurred predominantly because of an increase in the volume of the velopharynx (5.7+/-0.3 cm(3) vs 6.5+/-0.3 cm(3); p<0.001). This increase in airway calibre was associated with an increase in the lower anterior facial height (6.8+/-0.1 cm vs 7.5+/-0.1 cm; p<0.001), reduction in the distance between the hyoid and posterior nasal spine (7.4+/-0.1 cm vs 7.2+/-0.1 cm; p<0.001), lateral displacement of the parapharyngeal fat pads away from the airway (right parapharyngeal fat pad 0.17+/-0.02 cm; left parapharyngeal fat pad 0.22+/-0.02 cm) and anterior movement of the tongue base muscles (0.33+/-0.03 cm). Subanalyses in responders and non-responders to MAS treatment showed that the increase in upper airway calibre with mandibular advancement occurred only in responders. CONCLUSION: These results suggest that the mechanism of action of MAS is to increase the volume of the upper airway, predominantly by increasing the volume of the velopharynx, and this increased volume is associated with changes in the surrounding bony and soft tissue structures.

Differences in craniofacial structures and obesity in Caucasian and Chinese patients with obstructive sleep apnea.

STUDY OBJECTIVES: To explore differences in craniofacial structures and obesity between Caucasian and Chinese patients with obstructive sleep apnea (OSA). DESIGN: Inter-ethnic comparison study. SETTING: Two sleep disorder clinics in Australia and Hong Kong. PATIENTS: 150 patients with OSA (74 Caucasian, 76 Chinese). INTERVENTIONS: Anthropometry, cephalometry, and polysomnography were performed and compared. Subgroup analyses after matching for: (1) body mass index (BMI); (2) OSA severity. MEASUREMENTS AND RESULTS: The mean age and BMI were similar between the ethnic groups. Chinese patients had more severe OSA (AHI 35.3 vs 25.2 events/h, P = 0.005). They also had more craniofacial bony restriction, including a shorter cranial base (63.6 +/- 3.3 vs 77.5 +/- 6.7 mm, P < 0.001), maxilla (50.7 +/- 3.7 vs 58.8 +/- 4.3 mm, P < 0.001) and mandible length (65.4 +/- 4.2 vs 77.9 +/- 9.4 mm, P < 0.001). These findings remained after correction for differences in body height. Similar results were shown in the BMI-matched analysis (n = 66). When matched for OSA severity (n = 52), Chinese patients had more craniofacial bony restriction, but Caucasian patients were more overweight (BMI 30.7 vs 28.4 kg/m2, P = 0.03) and had a larger neck circumference (40.8 vs 39.1 cm, P = 0.004); however, the ratios of BMI to the mandible or maxilla size were similar. CONCLUSIONS: Craniofacial factors and obesity contribute differentially to OSA in Caucasian and Chinese patients. For the same degree of OSA severity, Caucasians were more overweight, whereas Chinese exhibited more craniofacial bony restriction.

Relationship between surface facial dimensions and upper airway structures in obstructive sleep apnea.

STUDY OBJECTIVES: We hypothesized that the facial phenotype is closely linked to upper airway anatomy. The aim of this study was to investigate the relationship between surface facial dimensions and upper airway structures using magnetic resonance imaging (MRI) in subjects with obstructive sleep apnea (OSA). DESIGN: Cohort study. SETTING: Sleep investigation unit. PATIENTS: Sixty-nine patients (apnea-hypopnea index > or = 10/h) underwent MRI as part of a study of upper airway anatomy in oral appliance therapy. INTERVENTIONS: Measurements of a range of surface facial dimensions and upper airway soft tissue volumes were performed on the MR images using image-analysis software. Pearson correlation analyses were performed. MEASUREMENTS AND RESULTS: Significant correlations were identified between a number of surface facial dimensions and neck circumference. Significant positive correlations were demonstrated between surface facial dimensions (including facial widths, facial heights, nose width, interocular and intercanthal widths) and upper airway structures. The strongest associations were between the tongue volume and the midface width (r = 0.70, P < 0.001), and lower-face width (r = 0.60, P <0.001). Surface facial dimensions in combination were also strong determinants for tongue volume (r2 = 0.69). Correlations between surface soft tissue thickness and upper airway soft tissue volumes occurred at the level of the midface but not at the level of the lower face. CONCLUSIONS: This study demonstrates that there is a relationship between surface facial dimensions and upper airway structures in subjects with OSA. These findings support the potential role of surface facial measurements in anatomic phenotyping for OSA.

Craniofacial phenotyping in obstructive sleep apnea--a novel quantitative photographic approach.

STUDY OBJECTIVES: To compare the craniofacial morphological phenotype of subjects with and without obstructive sleep apnea (OSA) using a quantitative photographic analysis technique. DESIGN: Case-control study; subgroup matched for body mass index (BMI) and sex. SETTING: Sleep investigation unit in a university teaching hospital. PATIENTS: 114 subjects (93% Caucasian) with OSA (apnea-hypopnea index [AHI] > or = 10/h) and 66 controls (AHI < 10/h). INTERVENTIONS: Standardized frontal-profile craniofacial photographic imaging performed prior to polysomnography. Photographs were analyzed for the computation of linear, angular, area and polyhedral volume measurements representing dimensions and relationships of the various craniofacial regions. MEASUREMENTS AND RESULTS: Photographic craniofacial phenotypic differences were demonstrated between OSA and control subjects, including a range of measurements of the face, mandible, maxilla, eyes, nose, head and neck. After 1-for-1 subgroup matching for BMI and sex (51 subjects in each group), mandibular length 1 (6.21 +/- 0.08 [mean +/- SEM] vs. 6.58 +/- 0.08 cm, P = 0.006), mandibular-nasion angle 1 (35.0 +/- 0.48 vs. 36.7 +/- 0.37 degrees, P = 0.006) and anterior neck space area (10.2 +/- 0.53 vs. 12.2 +/- 0.52 cm2, P = 0.01) remained smaller in the OSA group. Mandibular width-length angle (88.0 +/- 0.75 vs. 85.3 +/- 0.54 degrees, P = 0.005) and face width-midface depth angle (72.3 +/- 0.44 vs. 70.7 +/- 0.39 degrees, P = 0.01) remained larger in the OSA group, whereas mandibular triangular area (39.2 +/- 0.63 vs. 41.7 +/- 0.74 cm2, P = 0.01) was smaller. CONCLUSIONS: Craniofacial phenotypic differences in OSA in Caucasian subjects can be demonstrated using a photographic analysis technique.

Prediction of obstructive sleep apnea with craniofacial photographic analysis.

STUDY OBJECTIVES: To develop models based on craniofacial photographic analysis for the prediction of obstructive sleep apnea (OSA). DESIGN: Prospective cohort study. SETTING: Sleep investigation unit in a university teaching hospital. PATIENTS: One hundred eighty subjects (95.6% Caucasian) referred for the initial investigation of OSA were recruited consecutively. INTERVENTIONS: Clinical assessment and frontal-profile craniofacial photographic analyses were performed prior to polysomnography. Prediction models for determining the presence of OSA (apnea-hypopnea index [AHI] > or =10) were developed using logistic regression analysis and classification and regression trees (CART). MEASUREMENTS AND RESULTS: Obstructive sleep apnea was present in 63.3% of subjects. Using logistic regression, a model with 4 photographic measurements (face width, eye width, cervicomental angle, and mandibular length 1) correctly classified 76.1% of subjects with and without OSA (sensitivity 86.0%, specificity 59.1%, area under the receiver operating characteristics curve [AUC] 0.82). Combination of photographic and other clinical data improved the prediction (AUC 0.87), whereas prediction based on clinical assessment alone was lower (AUC 0.78). The optimal CART model provided a similar overall classification accuracy of 76.7%. Based on this model, 59.4% of the subjects were classified as either high or low risk with positive predictive value of 90.9% and negative predictive value of 94.7%, respectively. The remaining 40.6% of subjects have intermediate risk of OSA. CONCLUSIONS: Craniofacial photographic analysis provides detailed anatomical data useful in the prediction of OSA. This method allows OSA risk stratification by craniofacial morphological phenotypes.

Craniofacial Phenotyping in Chinese and Caucasian Patients With Sleep Apnea: Influence of Ethnicity and Sex.

STUDY OBJECTIVES: Craniofacial abnormalities are a risk factor for obstructive sleep apnea (OSA). We have previously shown that phenotypic information derived from craniofacial photographs predict OSA in sleep clinic populations. However, there are likely ethnic and sex differences in craniofacial phenotypes related to OSA. We aimed to assess the use of craniofacial photography to identify interactions between OSA, ethnicity, and sex in craniofacial phenotype. METHODS: Frontal and profile craniofacial photographs were analyzed from two sleep clinic populations of different ethnicity (Hong Kong Chinese, Australian Caucasians). OSA was defined as apnea-hypopnea index (AHI) > 10 events/h. Ten craniofacial measurements (three angles relating to jaw position and seven ratios describing proportions of the face) were examined for interactions between OSA status and sex or ethnicity) using factorial analysis of variance. RESULTS: A total of 363 subjects (25% female) were included (n = 200 Chinese, n = 163 Caucasian), of which 33% were controls. There were two-way interactions for OSA with both sex (mandibular plane angle [F = 7.0, P = .009], face / eye width ratio [F = 4.7, P = .032], maxillary / mandibular volume ratio [F = 9.2, P = .003]) and ethnicity (face / nose width ratio [F = 4.0, P = .045], mandibular width / length ratio [F = 5.1, P = .024], maxillary / mandibular volume ratio [F = 11.0, P = .001]). CONCLUSIONS: We provide evidence of ethnic and sex differences in facial phenotype related to OSA. Furthermore, we demonstrate that craniofacial photography can be used as a phenotypic tool to assess these differences and allow investigation of OSA phenotypes in large samples. This has relevance to personalizing OSA recognition strategies across different populations.

Dental appliance treatment for obstructive sleep apnea.

Oral appliances for the treatment of obstructive sleep apnea (OSA) are worn during sleep to maintain the patency of the upper airway by increasing its dimensions and reducing its collapsibility. Oral appliances are a simpler alternative to continuous positive airway pressure (CPAP). Over the last decade, there has been a significant expansion of the evidence base to support the use of oral appliances, with robust studies demonstrating their efficacy. This work has been underpinned by the recognition of the importance of upper airway anatomy in the pathophysiology of OSA. The updated practice parameters of the American Academy of Sleep Medicine now recommend their use for mild-to-moderate OSA, or for patients with severe OSA who are unable to tolerate CPAP or refuse treatment with CPAP. Oral appliances have been shown to have a beneficial impact on a number of important clinical end points, including the polysomnographic indexes of OSA, subjective and objective measures of sleepiness, BP, aspects of neuropsychological functioning, and quality of life. Elucidation of the mechanism of action of oral appliances has provided insight into the factors that predict treatment response and may improve the selection of patients for this treatment modality. Longitudinal studies to characterize the long-term adverse effects of oral appliance use are now beginning to emerge. Although less efficacious than CPAP for improving the polysomnographic indexes of OSA, oral appliances are generally preferred by patients. This has the potential to translate to better patient adherence and may provide an equivalent health outcome.

Facial phenotyping by quantitative photography reflects craniofacial morphology measured on magnetic resonance imaging in Icelandic sleep apnea patients.

STUDY OBJECTIVES: (1) To determine whether facial phenotype, measured by quantitative photography, relates to underlying craniofacial obstructive sleep apnea (OSA) risk factors, measured with magnetic resonance imaging (MRI); (2) To assess whether these associations are independent of body size and obesity. DESIGN: Cross-sectional cohort. SETTING: Landspitali, The National University Hospital, Iceland. PARTICIPANTS: One hundred forty patients (87.1% male) from the Icelandic Sleep Apnea Cohort who had both calibrated frontal and profile craniofacial photographs and upper airway MRI. Mean ± standard deviation age 56.1 ± 10.4 y, body mass index 33.5 ± 5.05 kg/m(2), with on-average severe OSA (apnea-hypopnea index 45.4 ± 19.7 h(-1)). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Relationships between surface facial dimensions (photos) and facial bony dimensions and upper airway soft-tissue volumes (MRI) was assessed using canonical correlation analysis. Photo and MRI craniofacial datasets related in four significant canonical correlations, primarily driven by measurements of (1) maxillary-mandibular relationship (r = 0.8, P < 0.0001), (2) lower face height (r = 0.76, P < 0.0001), (3) mandibular length (r = 0.67, P < 0.0001), and (4) tongue volume (r = 0.52, P = 0.01). Correlations 1, 2, and 3 were unchanged when controlled for weight and neck and waist circumference. However, tongue volume was no longer significant, suggesting facial dimensions relate to tongue volume as a result of obesity. CONCLUSIONS: Significant associations were found between craniofacial variable sets from facial photography and MRI. This study confirms that facial photographic phenotype reflects underlying aspects of craniofacial skeletal abnormalities associated with OSA. Therefore, facial photographic phenotyping may be a useful tool to assess intermediate phenotypes for OSA, particularly in large-scale studies.

Non-positive airway pressure modalities: mandibular advancement devices/positional therapy.

Although positive airway pressure is the most efficacious treatment for obstructive sleep apnea (OSA), its clinical effectiveness is limited by its obtrusive interface. Two alternative treatment modalities used in clinical practice are mandibular advancement devices (MADs) and positional therapy. The goals in treatment of OSA are to prevent obstructive apneas and hypopneas, to improve symptoms, and to modify the increased cardiovascular risk. MADs achieve this by mechanically protruding the mandible, thereby increasing the dimensions of the upper airway and reducing its collapsibility. By avoiding supine sleep, positional therapy improves the patency of the upper airway in those with positional OSA. There is now a relatively strong evidence base to support the use of MADs in clinical practice, with research studies assessing the impact of treatment on a range of health outcomes. The revised clinical practice parameters of the American Academy of Sleep Medicine recommend their use for mild to moderate OSA; or for patients with severe OSA who are unable to tolerate or refuse treatment with positive airway pressure. The evidence base for positional therapy is emerging, but is less well developed. A better understanding of the range of OSA phenotypes and predictors of response to different treatment modalities is required to allow physicians to tailor the choice of treatment to the individual patient.