Relationship between Symptom Profiles and Endotypes among Patients with Obstructive Sleep Apnea: A Latent Class Analysis

Sex-specific age-related worsening of pathological endotypic traits in patients with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is more prevalent in men and older adults. Few studies have explored variations in pathological endotypic traits by age and sex using a large patient sample, offering insights into the development of the disease. Our study aims to examine how endotype characteristics of OSA vary across ages in different sex.

METHODS

A cross-sectional study was conducted, enrolling 2296 adult patients referred for in-laboratory diagnostic polysomnography at a single sleep center in Taiwan. Among them, 1374 had an apnea-hypopnea index ≥5. Using the "Phenotyping Using Polysomnography" method, we estimated four endotypic traits-arousal threshold, upper airway collapsibility, loop gain, and upper airway muscle compensation. Demographic and polysomnographic characteristics were compared between sexes and age groups. Generalized linear regression and generalized additive models were employed to explore the associations of sex and age with endotypic traits.

RESULTS

Men with OSA exhibited higher collapsibility and lower compensation than women (difference: 4.32 %eupnea and 4.49 %eupnea, respectively). Younger patients with OSA had a higher prevalence of obesity, more snoring symptoms, and lower loop gain compared to older patients. For men, age was correlated with increased collapsibility, increased loop gain, and decreased arousal threshold after 37 years old. Whereas in women, endotypic traits were not associated with age, except for an increase in loop gain with advancing age.

CONCLUSIONS

Personalized treatment options for OSA should take into consideration age and sex. Reducing loop gain could be a treatment objective for older patients with OSA.

Are scoring respiratory effort-related arousals worth the effort? --A study comparing outcomes between 4 % vs 3 % hypopnea scoring rules

STUDY OBJECTIVES

The respiratory effort-related arousal (RERA) has been combined with apneas and hypopneas into the respiratory disturbance index (RDI). RERAs are characterized by ≥ 10 s of increasing upper airway effort terminating in arousal without meeting hypopnea criteria. The recent change to hypopnea definitions now includes a ≥30 % reduction in airflow for 10 s with EITHER a 3 % oxygen desaturation OR an arousal. Consequently, many events previously categorized as RERAs will now be included in the 3 % hypopneas, likely reducing the number of events scored as RERAs. We hypothesized that the 3 % apnea-hypopnea index (3%AHI) would approximate the 4%RDI, with the number of 3 % RERAs being negligible.

RESEARCH QUESTION

How does the transition from the 4 % to the 3 % hypopnea rules impact the significance of RERAs in clinical practice, and how we should relate the AHI and RDI using the different hypopnea rules?

METHODS

We prospectively collected 76 consecutive polysomnography results in 4 adult age groups. We re-scored the respiratory events utilizing both the 3 % and the 4 % hypopnea rules and compared the outcomes.

RESULTS

Among 76 diagnostic studies (mean age 47.5 years, males 47.4 %), the 3 % RERA index [0.8 (0.0, 3.1)] [median (Q1, Q3)] was significantly lower than the 4 % RERA index [3.5 (1.0, 7.3)]. The 3%AHI was 3.07 ± 9.23 (mean ± SD) higher than the 4%RDI (p = 0.005). The 3%AHI was 8.63 ± 8.86 higher than the 4%AHI in all age groups (p < 0.001). This was mainly due to an increased hypopnea index (+8.51 ± 9.03, p < 0.001). In patients with obstructive sleep apnea (OSA), the 3%RERA contributes 4.3 % to the 3%RDI, while the 4%RERA contributes 27.7 % to the 4%RDI.

INTERPRETATIONS

Both 3%RDI and 3%AHI are higher than the 4%RDI, primarily due to identification of more hypopnea events, resulting in more patients being classified as having OSA. This change in criteria complicates the comparison of hypopnea and RERA contributions between sleep studies scored using the different hypopnea rules.

High arousal threshold is associated with metabolic syndrome in patients with obstructive sleep apnea

OBJECTIVE

Obstructive sleep apnea (OSA) is associated with metabolic syndrome (MetS). OSA patients with high arousal threshold (ArTH) are less easy to arouse, which leads to more severe hypoxic events. We explored the relationship between high ArTH and MetS in patients with OSA.

METHODS

We conducted a cross-sectional study of 112 patients with OSA (mean age 43.50 ± 11.64 years, 89.29 % male). High ArTH was based on an overnight polysomnography, and defined as none or one of the following conditions: apnea-hypopnea index (AHI) < 30 events/hour, minimum oxygen saturation > 82.5 %, or frequency of hypopnea events > 58.3 %. Metabolic syndrome and its components were defined according to the new International Diabetes Federation definition.

RESULTS

Among the 112 OSA patients, 51 (45.54 %) had MetS and 68 (60.71 %) had high ArTH. Logistic regression, after adjusting for confounders, showed that patients with high ArTH had higher odds for MetS (OR = 4.31, 95 % CI = 1.63-11.42, p = 0.003), central obesity (OR = 5.78, 95 % CI = 1.95-17.16, p = 0.002) and hypertriglyceridemia (OR = 2.84, 95 % CI = 1.11-7.28, p = 0.030) compared to patients with low ArTH. Furthermore, higher ArTH levels were associated with higher values for waist circumference (p-for-trend < 0.001), triglycerides (p-for-trend = 0.042), and systolic blood pressure (p-for-trend = 0.037). Moreover, patients with high ArTH had more apnea events and less hypopnea events.

CONCLUSIONS

High ArTH is associated with MetS in OSA patients. High ArTH is a marker of the severity of cardiometabolic comorbidity in OSA.

Research progress on the clinical subtyping of obstructive sleep apnea hypopnea syndrome

Obstructive sleep apnea hypopnea syndrome (OSAHS) is a common sleep-disordered breathing condition that exhibits a notable degree of heterogeneity, a feature not fully considered in current diagnostic and therapeutic strategies. This article reviews and analyzes research progress in the subtyping of OSAHS from multiple perspectives, including clinical feature-based subtyping, comorbidity-based subtyping, polysomnography (PSG) parameter-based subtyping, and other classification approaches. Existing studies have identified common subtypes based on clinical features and clarified the characteristics of different subgroups in comorbidity-based classifications; the rich data provided by PSG have helped optimize the classification of OSAHS; and multi-dimensional clustering has provided a more precise basis for individualized treatment. Although these studies have deepened the understanding of the heterogeneity of OSAHS, challenges such as significant differences among subtypes and insufficient evidence for alternative therapies remain. Future research should focus on identifying biomarkers and elucidating the underlying pathophysiological mechanisms to advance the development of precision treatments.

Sex differences in sleep and sleep-disordered breathing

PURPOSE OF REVIEW

There is increasing evidence for relevant sex differences in pathophysiology, symptom presentation and outcomes in obstructive sleep apnoea (OSA). However, research on sex differences and sex-specific phenotypes in sleep-disordered breathing (SDB) is still in its infancy and data on sex differences in other SDB is still very scarce.

RECENT FINDINGS

While OSA is more common in men than in premenopausal women, the prevalence of OSA doubles postmenopausally and becomes comparable to that of men. Women have a lower collapsibility of the upper airway and a lower arousal threshold. In addition, the rapid eye movement (REM)-apnoea-hypopnoea index (AHI) is typically higher in women than in men, but the non-REM-AHI and thus the total AHI is often lower. Women are often symptomatic at lower AHI and present more frequently with symptoms of sleep fragmentation and poor sleep quality. Both certain forms of OSA (e.g. REM-OSA) and certain phenotypes (e.g. COMISA) are more common in women. Men have a higher risk of high loop gain central sleep apnoea.

SUMMARY

For a better understanding of sex-typical phenotypes with the aim of a more targeted treatment approach of SDB, adequately powered studies on sex differences in SDB should be conducted.

Latent profile analysis of depression in US adults with obstructive sleep apnea hypopnea syndrome

Objective

This study used latent profile analysis to explore the level of depression among US adults with obstructive sleep apnea hypopnea syndrome (OSAHS) symptoms and to identify different latent categories of depression to gain insight into the characteristic differences between these categories.

Methods

The data of this study were obtained from the National Health and Nutrition Examination Survey (NHANES) database, and the subjects with OSAHS symptoms were aged 18 years and older. The latent profile analysis (LPA) method was used to fit the latent depression categories in subjects with OSAHS symptoms. The chi-square test, rank sum test, and binary logistic regression were used to analyze the influencing factors of depression subgroups in subjects with OSAHS symptoms.

Results

Three latent profiles were identified: low-level (83.7%), moderate-level (14.5%) and high-level (1.8%) depression. The scores of 9 items in the high-level depression group were higher than those in the other two groups. Among them, item 4 "feeling tired or lack of energy" had the highest score in all categories.

Conclusion

Depression in subjects with OSAHS symptoms can be divided into low-level, moderate-level and high-level depression. There are significant differences among different levels of depression in gender, marital status, PIR, BMI, smoking, general health condition, sleep duration and OSAHS symptom severity.

Endotypic traits of supine position and supine-predominant obstructive sleep apnoea in Asian patients

BACKGROUND

Over half of all cases of obstructive sleep apnoea (OSA) are classified as supine-related OSA; however, the pathological endotype during supine position is not fully understood. This study aims to investigate the endotypic traits of supine-predominant OSA and explore the variations in endotypic traits between the supine and lateral positions.

METHODS

We prospectively recruited 689 adult patients with OSA from a single sleep centre between April 2020 and December 2022. Endotypic traits, namely arousal threshold, collapsibility, loop gain and upper airway muscle compensation, were retrieved from polysomnographic signals. We identified spOSA by a supine to non-supine apnoea-hypopnoea index (AHI) ratio >2. We cross-sectionally compared demographic and endotypic traits between supine-predominant OSA and non-positional OSA and examined the associations between supine-predominant OSA and endotypic traits. Additionally, we compared the changes in endotypic traits between supine and lateral positions in patients with supine-predominant OSA and non-positional OSA.

RESULTS

In our study sample, 75.8% of patients were identified as having supine-predominant OSA. Compared to non-positional OSA, supine-predominant OSA was associated with low collapsibility (β= -3.46 %eupnoea, 95% CI -5.93- -1.00 %eupnoea) and reduced compensation (β= -6.79 %eupnoea, 95% CI -10.60- -2.99 %eupnoea). When transitioning from the lateral to supine position, patients with supine-predominant OSA had a substantial decrease in compensation compared to those with non-positional OSA (-11.98 versus -6.28 %eupnoea).

CONCLUSIONS

Supine-predominant OSA is the prevalent phenotype of OSA in Asian patients. Inadequate upper airway compensation appears to be a crucial underlying pathology in patients with supine-predominant OSA.