Defining the Heterogeneity of Sleep Apnea Syndrome: A Cluster Analysis With Implications for Patient Management

Phenotypes of obstructive sleep apnea in women: A real-life cohort study

OBJECTIVE

Obstructive sleep apnea (OSA) is a complex, heterogeneous disease. Categorizing the disorder into phenotypes can help us better understand its pathology and guide us toward more personalized treatment approaches. Nevertheless, most of the previous cluster analysis (CA) studies in OSA predominantly included middle-aged to older men and may not adequately represent the heterogeneity of OSA phenotypes in women. Our aim is to identify these phenotypes in women using an extensive, exclusively female cohort.

METHODS

Cross-sectional study of 1886 women diagnosed with OSA (apnea-hypopnea index >5 events/h) by PSG (polysomnography) and RP (respiratory polygraphy) at a tertiary hospital Sleep Unit. A CA was performed including general data, clinical variables, comorbidities and sleep study results.

RESULTS

Four phenotypic subtypes were identified: Cluster 1 "Middle-aged paucisymptomatic women without cardiovascular risk factors" (507 patients, 27 %); Cluster 2 "Older paucisymptomatic women with established cardiovascular disease and severe OSA" (228 patients, 12 %); Cluster 3 "Middle-aged women with "classic" symptoms and cardiovascular risk factors" (892 patients, 47 %), and Cluster 4 ″Middle-aged women with mood disorders, nonrestorative sleep and cardiovascular risk factors" (259 patients, 14 %).

CONCLUSIONS

Conducting a CA exclusively within a female cohort reveals a heterogeneous presentation of OSA in women, similar to what has been previously reported in the literature for men. The "classical" presentation is notably the most prevalent, while the "atypical" presentation, which was previously more frequently associated with women, is less prevalent. Additionally, paucisymptomatic presentations, with or without associated comorbidities, are also present.

Dysregulation in CD39/CD73 Axis May Trigger the Upsurge of the Immune Suppressive Agent Adenosine in OSA Patients

INTRODUCTION

Although higher incidence of cancer represents a major burden for obstructive sleep apnea (OSA) patients, the molecular pathways driving this association are not completely understood. Interestingly, adenosinergic signaling has emerged as a powerful immune checkpoint driving tumor development and progression.

METHODS

Here, we explored the expression of the adenosinergic ecto-enzymes CD39 and CD73 in T-lymphocytes of OSA patients without any evidence of cancer, as well as their soluble forms in plasma (sCD39 and sCD73), along with adenosine. In addition, we explored the role of intermittent hypoxia (IH) in this context by in vitro models.

RESULTS

Our results showed that CD39 is upregulated while CD73 is downregulated in OSA T-cells' membrane. Moreover, our findings suggest that IH, through HIF-1, mediates the upregulation of both CD39 and CD73; and that CD73 downregulation could be mediated by a higher release of sCD73 by OSA T-lymphocytes. Importantly, we found that both sCD39 and sCD73 are upregulated in OSA plasma, suggesting T-lymphocytes as a potential source for plasmatic sCD73. Finally, our data propose the alterations in CD39/CD73 axis could underlie the upsurge of adenosine levels in the plasma of OSA patients.

CONCLUSION

Our study reveals a hypoxia-mediated alteration of the CD39/CD73 axis in OSA patients, which could trigger ADO upregulation, thus potentially contributing to the immune suppressive environment and ultimately facilitating tumor development and progression. Therefore, our data highlights the need for new longitudinal studies evaluating CD39 and/or CD73 as potential cancer-risk prognostic biomarkers in OSA patients.

Role of Sleep Apnea and Long-Term CPAP Treatment in the Prognosis of Patients With Melanoma: A Prospective Multicenter Study of 443 Patients

BACKGROUND

OSA has been associated with increased incidence and aggressiveness of melanoma. However, the long-term impact of OSA and CPAP treatment on the prognosis of melanoma remains unexplored.

RESEARCH QUESTION

Are OSA and CPAP treatment associated independently with a poor prognosis for cutaneous melanoma?

STUDY DESIGN AND METHODS

Four hundred forty-three patients with a diagnosis of cutaneous melanoma (2012-2015) underwent a sleep study within 6 months of diagnosis. The main 5-year outcome of the study was a composite of melanoma recurrence, metastasis, or mortality. Patients were divided into four groups: baseline apnea-hypopnea index (AHI) of fewer than 10 events/h (no OSA; control group), OSA treated with CPAP and good adherence, untreated or poor CPAP adherence in moderate (AHI, 10-29 events/h), and severe OSA (AHI, ≥ 30 events/h). Survival analysis was used to determine the independent role of OSA and CPAP treatment on melanoma composite outcome.

RESULTS

Three hundred ninety-one patients (88.2%) were available for analysis at 5-year follow-up (mean age, 65.1 ± 15.2 years; 49% male; Breslow index, 1.7 ± 2.5 mm). One hundred thirty-nine patients had AHI of fewer than 10 events/h (control group); 78 patients with OSA were adherent to CPAP; and 124 and 50 patients had moderate and severe OSA, respectively, without CPAP treatment. Median follow-up was 60 months (interquartile range, 51-74 months). During follow-up, 32 relapses, 53 metastases, and 52 deaths occurred (116 patients showed at least one of the main composite outcomes). After adjusting for age, sex, sentinel lymph nodes affected at diagnosis, BMI, diabetes, nighttime with an oxygen saturation below 90%, Breslow index, Epworth sleepiness scale scores, and melanoma treatment, moderate (hazard ratio [HR], 2.45; 95% CI, 1.09-5.49) and severe OSA (HR, 2.96; 95% CI, 1.36-6.42) were associated with poorer prognosis of melanoma compared with the control group. However, good adherence to CPAP avoided this excess risk (HR, 1.66; 95% CI, 0.71-3.90).

INTERPRETATION

Moderate to severe untreated OSA is an independent risk factor for poor prognosis of melanoma. Treatment with CPAP is associated with improved melanoma outcomes compared with untreated moderate to severe OSA.

Polysomnographic Phenotypes of Obstructive Sleep Apnea in a Real-Life Cohort: A Pathophysiological Approach

INTRODUCTION

Obstructive sleep apnea (OSA) is heterogeneous and complex, but its severity is still based on the apnea-hypoapnea index (AHI). The present study explores using cluster analysis (CA), the additional information provided from routine polysomnography (PSG) to optimize OSA categorization.

METHODS

Cross-sectional study of OSA subjects diagnosed by PSG in a tertiary hospital sleep unit during 2016-2020. PSG, demographical, clinical variables, and comorbidities were recorded. Phenotypes were constructed from PSG variables using CA. Results are shown as median (interquartile range).

RESULTS

981 subjects were studied: 41% females, age 56 years (45-66), overall AHI 23events/h (13-42) and body mass index (BMI) 30kg/m2 (27-34). Three PSG clusters were identified: Cluster 1: "Supine and obstructive apnea predominance" (433 patients, 44%). Cluster 2: "Central, REM and shorter-hypopnea predominance" (374 patients, 38%). Cluster 3: "Severe hypoxemic burden and higher wake after sleep onset" (174 patients, 18%). Based on classical OSA severity classification, subjects are distributed among the PSG clusters as severe OSA patients (AHI≥30events/h): 46% in cluster 1, 17% in cluster 2 and 36% in cluster 3; moderate OSA (15≤AHI<30events/h): 57% in cluster 1, 34% in cluster 2 and 9% in cluster 3; mild OSA (5≤AHI<15events/h): 28% in cluster 1, 68% in cluster 2 and 4% in cluster 3.

CONCLUSIONS

The CA identifies three specific PSG phenotypes that do not completely agree with classical OSA severity classification. This emphasized that using a simplistic AHI approach, the OSA severity is assessed by an incorrect or incomplete analysis of the heterogeneity of the disorder.

Diagnosis and Treatment of Sleep Apnea in Children: A Future Perspective Is Needed

Obstructive sleep apnea (OSA) in children is a prevalent, but still, today, underdiagnosed illness, which consists of repetitive episodes of upper airway obstruction during sleep with important repercussions for sleep quality. OSA has relevant consequences in the pediatric population, mainly in the metabolic, cardiovascular (CV), and neurological spheres. However, contrary to adults, advances in diagnostic and therapeutic management have been scarce in the last few years despite the increasing scientific evidence of the deleterious consequences of pediatric OSA. The problem of underdiagnosis and the lack of response to treatment in some groups make an update to the management of OSA in children necessary. Probably, the heterogeneity of OSA is not well represented by the classical clinical presentation and severity parameters (apnea/hypopnea index (AHI)), and new strategies are required. A specific and consensus definition should be established. Additionally, the role of simplified methods in the diagnosis algorithm should be considered. Finally, the search for new biomarkers for risk stratification is needed in this population. In conclusion, new paradigms based on personalized medicine should be implemented in this population.

Potential Pathophysiological Pathways in the Complex Relationships between OSA and Cancer

Several epidemiological and clinical studies have suggested a relationship between obstructive sleep apnea (OSA) and a higher incidence or severity of cancer. This relationship appears to be dependent on a myriad of factors. These include non-modifiable factors, such as age and gender; and modifiable or preventable factors, such as specific comorbidities (especially obesity), the use of particular treatments, and, above all, the histological type or location of the cancer. Heterogeneity in the relationship between OSA and cancer is also related to the influences of intermittent hypoxemia (a hallmark feature of OSA), among others, on metabolism and the microenvironment of different types of tumoral cells. The hypoxia inducible transcription factor (HIF-1α), a molecule activated and expressed in situations of hypoxemia, seems to be key to enabling a variety of pathophysiological mechanisms that are becoming increasingly better recognized. These mechanisms appear to be operationally involved via alterations in different cellular functions (mainly involving the immune system) and molecular functions, and by inducing modifications in the microbiome. This, in turn, may individually or collectively increase the risk of cancer, which is then, further modulated by the genetic susceptibility of the individual. Here, we provide an updated and brief review of the different pathophysiological pathways that have been identified and could explain the relationship between OSA and cancer. We also identify future challenges that need to be overcome in this intriguing field of research.

Defining the Profile of Obstructive Sleep Apnea in Women Compared to Men

Background: The importance of understanding the presentation of obstructive sleep apnea (OSA) in women has been increasingly recognized. Although there is some insight that there are significant differences in presentation between women and men, the consequences of such differences, particularly for treatment have not yet been fully identified. Thus, the objective of this study was to determine the phenotype of OSA in women. Materials and Methods: Study of a population-based clinical cohort of 2022 patients with OSA confirmed by polygraphy or polysomnography (apnea-hypopnea index [AHI] >5/hour). Comorbidities, symptoms, physical examination, current medical treatments, and sleep parameters were recorded. Results: A total of 709 women and 1313 men were included in this study. After adjustment for anthropometric characteristics, morphological alterations, and previous treatment, women were found to have lower AHI values (25.3 ± 1.2 vs. 35.0 ± 0.9; p < 0.001), desaturation index (24.4 ± 1.2 vs. 33.2 ± 0.9; p < 0.001), and saturation time <90% (18.8 ± 1.3 vs. 24.1 ± 1.0; p < 0.001) compared with men. Furthermore, women had a lower risk of witnessed apnea (odds ratio adjusted [ORa] for baseline characteristics and sleep parameters), (ORa: 0.53, 95% confidence interval [CI]: 0.40-0.71), reduced sensation of restful sleep (ORa: 0.50, 95% CI: 0.38-0.66), greater fatigue (ORa: 2.68, 95% CI: 1.86-3.86), headache (ORa: 3.00, 95% CI: 2.26-3.97), memory disorders (ORa: 1.836, 95% CI: 1.40-2.41), insomnia (ORa: 2.09, 95% CI: 1.50-2.93), and excessive daytime sleepiness (ORa: 1.41, 95% CI: 1.03-1.92), with interference in their daily activities (ORa: 1.54, 95% CI: 1.17-2.03). Likewise, after adjustment for anthropometric characteristics and sleep parameters, women also showed higher risk of depression (ORa: 4.31, 95% CI: 3.15-5.89) and anxiety (ORa: 3.18, 95% CI: 2.38-4.26). Conclusions: Our findings suggest that women present a specific OSA phenotype, with a probable implication for clinical, diagnostic, and therapeutic management.