Physiological consequences of CPAP therapy withdrawal in patients with obstructive sleep apnoea-an opportunity for an efficient experimental model

Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity

BACKGROUND

Obstructive sleep apnea is characterized by disordered breathing during sleep and is associated with major cardiovascular complications; excess adiposity is an etiologic risk factor. Tirzepatide may be a potential treatment.

METHODS

We conducted two phase 3, double-blind, randomized, controlled trials involving adults with moderate-to-severe obstructive sleep apnea and obesity. Participants who were not receiving treatment with positive airway pressure (PAP) at baseline were enrolled in trial 1, and those who were receiving PAP therapy at baseline were enrolled in trial 2. The participants were assigned in a 1:1 ratio to receive either the maximum tolerated dose of tirzepatide (10 mg or 15 mg) or placebo for 52 weeks. The primary end point was the change in the apnea-hypopnea index (AHI, the number of apneas and hypopneas during an hour of sleep) from baseline. Key multiplicity-controlled secondary end points included the percent change in AHI and body weight and changes in hypoxic burden, patient-reported sleep impairment and disturbance, high-sensitivity C-reactive protein (hsCRP) concentration, and systolic blood pressure.

RESULTS

At baseline, the mean AHI was 51.5 events per hour in trial 1 and 49.5 events per hour in trial 2, and the mean body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) was 39.1 and 38.7, respectively. In trial 1, the mean change in AHI at week 52 was -25.3 events per hour (95% confidence interval [CI], -29.3 to -21.2) with tirzepatide and -5.3 events per hour (95% CI, -9.4 to -1.1) with placebo, for an estimated treatment difference of -20.0 events per hour (95% CI, -25.8 to -14.2) (P<0.001). In trial 2, the mean change in AHI at week 52 was -29.3 events per hour (95% CI, -33.2 to -25.4) with tirzepatide and -5.5 events per hour (95% CI, -9.9 to -1.2) with placebo, for an estimated treatment difference of -23.8 events per hour (95% CI, -29.6 to -17.9) (P<0.001). Significant improvements in the measurements for all prespecified key secondary end points were observed with tirzepatide as compared with placebo. The most frequently reported adverse events with tirzepatide were gastrointestinal in nature and mostly mild to moderate in severity.

CONCLUSIONS

Among persons with moderate-to-severe obstructive sleep apnea and obesity, tirzepatide reduced the AHI, body weight, hypoxic burden, hsCRP concentration, and systolic blood pressure and improved sleep-related patient-reported outcomes. (Funded by Eli Lilly; SURMOUNT-OSA ClinicalTrials.gov number, NCT05412004.).

Factors Associated with Persistent Obstructive Sleep Apnea After Bariatric Surgery: A Narrative Review

The prevalence of obstructive sleep apnea (OSA) among the bariatric surgery population is estimated to be 45-70%. However, weight loss obtained by bariatric surgery is not always associated with full remission of OSA, suggesting that other confounding factors are present. This article aims to review the current literature, focusing on factors that could predict the persistence of OSA after bariatric surgery. For this purpose, relevant studies of more than 50 patients that assessed pre- and post-operative presence and severity of OSA detected by poly(somno)graphy (PG/PSG) in bariatric populations were collected. Six retrospective and prospective studies were evaluated that included 1302 OSA patients, with a BMI range of 42.6 to 56 kg/m2, age range of 44.8 to 50.7 years, and percentage of women ranging from 45% to 91%. The studies were very heterogeneous regarding type of bariatric surgery, diagnostic criteria for OSA and OSA remission, and delay of OSA reassessment. OSA remission was observed in 26% to 76% of patients at 11-12 months post-surgery. Loss to follow-up was high in all studies, leading to a potential underestimation of OSA remission. Based on this limited sample of bariatric patients, age, pre-operative OSA severity, proportion of weight loss, and type 2 diabetes (T2D) were identified as factors associated with OSA persistence but the results were inconsistent between studies regarding the impact of age and the magnitude of weight loss. Several other factors may potentially lead to OSA persistence in the bariatric surgery population, such as fat distribution, ethnicity, anatomical predisposition, pathophysiological traits, supine position, and REM-predominant hypopnea and apnea. Further well-conducted multicentric prospective studies are needed to document the importance of these factors to achieve a better understanding of OSA persistence after bariatric surgery in obese patients.

Long-term health outcomes for patients with obstructive sleep apnea: placing the Agency for Healthcare Research and Quality report in context-a multisociety commentary

This multisociety commentary critically examines the Agency for Healthcare Research and Quality (AHRQ) final report and systematic review on long-term health outcomes in obstructive sleep apnea. The AHRQ report was commissioned by the Centers for Medicare & Medicaid Services and particularly focused on the long-term patient-centered outcomes of continuous positive airway pressure, the variability of sleep-disordered breathing metrics, and the validity of these metrics as surrogate outcomes. This commentary raises concerns regarding the AHRQ report conclusions and their potential implications for policy decisions. A major concern expressed in this commentary is that the AHRQ report inadequately acknowledges the benefits of continuous positive airway pressure for several established, long-term clinically important outcomes including excessive sleepiness, motor vehicle accidents, and blood pressure. While acknowledging the limited evidence for the long-term benefits of continuous positive airway pressure treatment, especially cardiovascular outcomes, as summarized by the AHRQ report, this commentary reviews the limitations of recent randomized controlled trials and nonrandomized controlled studies and the challenges of conducting future randomized controlled trials. A research agenda to address these challenges is proposed including study designs that may include both high quality randomized controlled trials and nonrandomized controlled studies. This commentary concludes by highlighting implications for the safety and quality of life for the millions of people living with obstructive sleep apnea if the AHRQ report alone was used by payers to limit coverage for the treatment of obstructive sleep apnea while not considering the totality of available evidence.

CITATION

Patil SP, Billings ME, Bourjeily G, et al. Long-term health outcomes for patients with obstructive sleep apnea: placing the Agency for Healthcare Research and Quality report in context-a multisociety commentary. J Clin Sleep Med. 2024;20(1):135-149.

Unexpected Resolution of Obstructive Sleep Apnea after Nasal Surgery in a Patient Nonadherent to Continuous Positive Airway Pressure Therapy

Continuous positive airway pressure (CPAP) is recommended as first-line therapy in cases of moderate-to-severe obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) prevents upper airway obstruction and abolishes apnea or hypopnea events during sleep. But up to 50% of OSA patients may be nonadherent to CPAP due to various causes, including nasal obstruction. Nasal surgery may improve CPAP compliance in some OSA patients but is not regarded as OSA therapy. Here, I report a patient non-adherent to CPAP whose sleep apnea resolved unexpectedly after nasal surgery to increase adherence to CPAP.

Experimental Models to Study End-Organ Morbidity in Sleep Apnea: Lessons Learned and Future Directions

Sleep apnea (SA) is a very prevalent sleep breathing disorder mainly characterized by intermittent hypoxemia and sleep fragmentation, with ensuing systemic inflammation, oxidative stress, and immune deregulation. These perturbations promote the risk of end-organ morbidity, such that SA patients are at increased risk of cardiovascular, neurocognitive, metabolic and malignant disorders. Investigating the potential mechanisms underlying SA-induced end-organ dysfunction requires the use of comprehensive experimental models at the cell, animal and human levels. This review is primarily focused on the experimental models employed to date in the study of the consequences of SA and tackles 3 different approaches. First, cell culture systems whereby controlled patterns of intermittent hypoxia cycling fast enough to mimic the rates of episodic hypoxemia experienced by patients with SA. Second, animal models consisting of implementing realistic upper airway obstruction patterns, intermittent hypoxia, or sleep fragmentation such as to reproduce the noxious events characterizing SA. Finally, human SA models, which consist either in subjecting healthy volunteers to intermittent hypoxia or sleep fragmentation, or alternatively applying oxygen supplementation or temporary nasal pressure therapy withdrawal to SA patients. The advantages, limitations, and potential improvements of these models along with some of their pertinent findings are reviewed.

Socioeconomic status impacts blood pressure response to positive airway pressure treatment

STUDY OBJECTIVES

Positive airway pressure (PAP) treatment of obstructive sleep apnea (OSA) reduces blood pressure (BP). Retrospective data suggest that African Americans (AA), a group at high-risk for hypertensive organ dysfunction, may have a greater BP response to PAP therapy than European Americans (EA). We examined the difference in 24-hour BP response to three months of PAP treatment between AA and EA.

METHODS

Participants (N=259, 161 AA and 98 EA) with apnea-hypopnea index (AHI) ≥15/hour from two prospective cohorts were included. T-tests and multiple linear regression were used to examine BP outcomes in AA vs. EA, adjusting for PAP adherence, socioeconomic status (SES), and baseline characteristics.

RESULTS

Participants were middle-aged (mean ± standard deviation, 53.8±9.3 years), 86% (227) men, AHI 35.6±19.2/hour, and PAP adherence of 3.36±2.24 hours/day. The reductions in 24-hour systolic and diastolic BP (mm Hg) were not different in AA vs. EA (systolic=-1.13±12.1 vs. -0.61±12.8, p=0.80 and diastolic=-0.74±7.9 vs. -0.80±7.4, p=0.96), and race was not a predictor of 24-hour systolic or diastolic BP reduction (p=0.75 and 0.54). SES and PAP adherence demonstrated a significant interaction; low SES was associated with an increase in 24-hour systolic BP (β=19.3, p=0.03) in the absence of PAP use but a greater reduction in 24-hour systolic BP with higher PAP adherence (β=-3.96, p=0.03).

CONCLUSIONS

24-hour BP response to PAP treatment is similar in AA and EA. Adherence to PAP treatment is more effective in improving 24-hour systolic BP in those with low SES.

The study was a clinical trial. Clinical Trial Registration: NCT01960465 and NCT01578031.

Sleep-disordered breathing and cerebral small vessel disease-acute and 6 months after ischemic stroke

PURPOSE

Sleep-disordered breathing (SDB) occurs frequently after stroke and is associated with poor functional outcome and increased mortality. The purpose of this study was to detect changes in SDB over time after acute ischemic stroke and investigate relationships between SDB and stroke etiologies with focus on cerebral small vessel disease.

METHODS

From May 2015 to August 2016, we conducted an observational study of 99 patients with mild to moderate stroke (median age: 68 years, range 36-88; 56% men). Polysomnography was performed within 7 days of stroke onset (n = 91) and after 6 months (n = 52). The strokes were classified using the etiological TOAST classification. Total small vessel disease (SVD) scores were calculated based on MRIs.

RESULTS

SDB, defined as an apnea-hypopnea index (AHI) ≥ 15, was found in 56% of patients in the acute state and in 44% at follow-up. AHI decreased over time (median change 4.7, 95% confidence interval [95% CI] 0.5-8.9; p = 0.03). Patients with AHI ≥ 15 in both the acute state and at follow-up had higher SVD score at follow-up (p = 0.003). AHI was not associated with ischemic stroke subgroups according to the TOAST classification.

DISCUSSION

In conclusion, 6 months after stroke, AHI decreased, but 44% still had AHI ≥ 15. Persistent SDB in both the acute state and at follow-up was associated with a higher SVD score, but not to the TOAST subgroups. SDB evaluation should be offered to stroke patients, and the effect of SDB on cerebral small vessel disease needs to be further investigated using the well-defined SVD score.

TRIAL REGISTRATION

clinicaltrials.gov NCT02111408, April 11, 2014.

A Novel Model to Estimate Key Obstructive Sleep Apnea Endotypes from Standard Polysomnography and Clinical Data and Their Contribution to Obstructive Sleep Apnea Severity

Rationale: There are at least four key pathophysiological endotypes that contribute to obstructive sleep apnea (OSA) pathophysiology. These include 1) upper-airway collapsibility (Pcrit); 2) arousal threshold; 3) loop gain; and 4) pharyngeal muscle responsiveness. However, an easily interpretable model to examine the different ways and the extent to which these OSA endotypes contribute to conventional polysomnography-defined OSA severity (i.e., the apnea-hypopnea index) has not been investigated. In addition, clinically deployable approaches to estimate OSA endotypes to advance knowledge on OSA pathogenesis and targeted therapy at scale are not currently available.Objectives: Develop an interpretable data-driven model to 1) determine the different ways and the extent to which the four key OSA endotypes contribute to polysomnography-defined OSA severity and 2) gain insight into how standard polysomnographic and clinical variables contribute to OSA endotypes and whether they can be used to predict OSA endotypes.Methods: Age, body mass index, and eight polysomnography parameters from a standard diagnostic study were collected. OSA endotypes were also quantified in 52 participants (43 participants with OSA and nine control subjects) using gold-standard physiologic methodology on a separate night. Unsupervised multivariate principal component analyses and data-driven supervised machine learning (decision tree learner) were used to develop a predictive algorithm to address the study objectives.Results: Maximum predictive performance accuracy of the trained model to identify standard polysomnography-defined OSA severity levels (no OSA, mild to moderate, or severe) using the using the four OSA endotypes was approximately twice that of chance. Similarly, performance accuracy to predict OSA endotype categories ("good," "moderate," or "bad") from standard polysomnographic and clinical variables was approximately twice that of chance for Pcrit and slightly lower for arousal threshold.Conclusions: This novel approach provides new insights into the different ways in which OSA endotypes can contribute to polysomnography-defined OSA severity. Although further validation work is required, these findings also highlight the potential for routine sleep study and clinical data to estimate at least two of the key OSA endotypes using data-driven predictive analysis methodology as part of a clinical decision support system to inform scalable research studies to advance OSA pathophysiology and targeted therapy for OSA.

Differential associations of hypoxia, sleep fragmentation, and depressive symptoms with cognitive dysfunction in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete cessation of breathing during sleep and increased effort to breathe. This study examined patients who underwent overnight polysomnographic studies in a major sleep laboratory in Saudi Arabia. The study aimed to determine the extent to which intermittent hypoxia, sleep disruption, and depressive symptoms are independently associated with cognitive impairments in OSA. In the sample of 90 participants, 14 had no OSA, 30 mild OSA, 23 moderate OSA, and 23 severe OSA. The findings revealed that hypoxia and sleep fragmentation are independently associated with impairments of sustained attention and reaction time (RT). Sleep fragmentation, but not hypoxia, was independently associated with impairments in visuospatial deficits. Depressive symptoms were independently associated with impairments in the domains of sustained attention, RT, visuospatial ability, and semantic and episodic autobiographical memories. Since the depressive symptoms are independent of hypoxia and sleep fragmentation, effective reversal of cognitive impairment in OSA may require treatment interventions that target each of these factors.

Predictors of changes in subjective daytime sleepiness in response to CPAP therapy withdrawal in OSA: A post-hoc analysis

Subjective sleepiness is the hallmark symptom of untreated obstructive sleep apnea (OSA) and leads to an increased risk of motor vehicle accidents and impaired quality of life. Continuous positive airway pressure (CPAP) is the standard therapy for OSA and improves sleepiness. The aim was to identify factors that might predict recurrence of sleepiness in times off CPAP and to define OSA patient types with a likely effect of CPAP on sleepiness. A post-hoc analysis of six clinical trials, including 132 patients with OSA effectively treated with CPAP prior to study inclusion, who were allocated to 2 weeks of CPAP withdrawal, was conducted to assess predictors of a change in subjective sleepiness. A multivariate regression model was used to assess predictors of a change in the Epworth Sleepiness Scale (ESS) score. In response to CPAP withdrawal, the median apnea-hypopnea index (AHI) and the ESS score significantly increased compared to baseline on CPAP by 32.6/hr (95% CI, 28.8, 36.4)/hr and 2.5 (95% CI, 1.8,3.2), respectively (p < .001), in the included 132 patients. There was an independent positive association of AHI (Coef. [95% CI] 0.04 [0.01, 0.08]) with an increase in ESS score upon CPAP withdrawal, and an independent negative association of age (coef. [95% CI], -0.10 [-0.18, -0.2]), ESS on CPAP (coef. [95% CI], -0.21 [-0.40, -0.015]) and active smoking status (coef. [95% CI], -1.22 [-2.26, -0.17]). These findings suggest that younger patients with a low residual sleepiness on CPAP and a recurrence of more severe OSA during CPAP withdrawal are at highest risk of suffering from a clinically relevant return of daytime sleepiness in times off CPAP.

Effect of exercise training on subjective parameters in patients with obstructive sleep apnea: a systematic review and meta-analysis

Obstructive sleep apnea (OSA) has many effects on subjective parameters of the disease, such as reduction in quality of life (QoL), sleep quality (SQ), and increases in daytime sleepiness. Studies have reported the beneficial effect of exercise training on OSA severity; however, whether it improves subjective parameters remains unclear. The purpose of the present review was to investigate the effect of exercise training on QoL, daytime sleepiness, and SQ in adults with OSA by summarizing the results of clinical trials. The study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered in PROSPERO. A systematic review of the PubMed, Scopus, and Cochrane (CENTRAL) databases was conducted. Risk of bias analysis was performed using the Cochrane tool, and Review Manager version 5.2 (R Foundation for Statistical Computing, Vienna, Austria) was used to perform the meta-analysis. Of the 1573 studies initially retrieved, 8 relevant studies with 228 participants were included in the analysis. The studies presented moderate risk of bias. Exercise training significantly improved QoL (mean difference, 12.9 [95% confidence interval (CI) 6.4 to 19.5]) and SQ (mean difference, -2.0 [95% CI -3.6 to -0.5]), and reduced daytime sleepiness (mean difference, -3.7 [95% CI -6.1 to -1.2]), and OSA severity (mean difference, -11.4 [95% CI -13.4 to -9.4 events/h]). Thus, physical exercise training was effective in improving subjective parameters and reducing the severity of OSA. Additional randomized clinical trials, however, should be performed to confirm these findings.

Lung air trapping lowers respiratory arousal threshold and contributes to sleep apnea pathogenesis in COPD patients with overlap syndrome

STUDY OBJECTIVES

Overlap syndrome occurs when obstructive sleep apnea (OSA) and chronic obstructive pulmonary disorder (COPD) coexist in the same patient. Although several studies highlighted the importance of clinical phenotyping in OSA, the trait contribution to OSA pathogenesis in overlap syndrome has not been investigated. With this pilot study, we aimed to measure OSA determinants and their relationship with functional respiratory parameters in a sample of patients with overlap syndrome. In particular, we hypothesize that patients with COPD have in the low arousal threshold a major contributor for the development of OSA.

METHODS

Ten consecutive non-hypercapnic COPD patients (body mass index<35 kg/m²) suffering from overlap syndrome with no other relevant comorbidities underwent a phenotyping polysomnography. Traits were measured with CPAP dial-downs.

RESULTS

Arousal threshold was found to be inversely associated to functional measures of lung air trapping and static hyperinflation. Particularly, correlations with residual volume (r² = 0.49, p =  0.024) and residual volume to total lung capacity ratio (r² = 0.48, p =  0.026) were evident. Only 20% of patients showed a high upper airway passive collapsibility as single pathological trait. In contrast, among those patients with multiple altered traits (6 out of 10), all had an elevated loop gain and 4 (∼65%) a low arousal threshold.

CONCLUSIONS

High loop gain and particularly low arousal threshold seem important contributors to OSA pathogenesis and severity in patients with COPD. Recognizing in COPD patients these features as key traits may open avenues for personalized medicine in the field of overlap syndrome.