Elevated Serum Markers of Acute Kidney Injury in Patients With Obstructive Sleep Apnea

Evaluating cystatin-C and monocyte-to-high-density lipoprotein cholesterol ratio as indicators of obstructive sleep apnea severity in male patients

Objectives

This study investigates the association between blood cystatin-C (Cys-C) and monocyte-to-high-density lipoprotein cholesterol ratio (MHR), both established inflammatory markers, with the severity of obstructive sleep apnea (OSA) in male patients.

Methods

A total of 117 male participants who underwent overnight polysomnography (PSG) between February 2019 and December 2022 were included. Based on the apnea-hypopnea index (AHI), participants were categorized into three groups: G1 (AHI < 5 events/hour, n = 9; control group), G2 (5 ≤ AHI < 30 events/hour, n = 32), and G3 (AHI ≥ 30 events/hour, n = 76). Serum Cys-C and MHR levels were measured and analyzed for their correlation with OSA severity. Multivariate logistic regression and receiver operating characteristic (ROC) analyses assessed their diagnostic value, while restricted cubic spline (RCS) analysis examined potential nonlinear relationships.

Results

Cys-C and MHR levels increased with OSA severity and showed significant positive correlations with AHI (Cys-C: r = 0.084, P < 0.05; MHR: r = 0.1286, P < 0.05). In multivariate regression, MHR remained an independent correlate of OSA severity (adjusted OR = 47.130, 95% CI: 1.014-6.692, P = 0.008), whereas Cys-C lost statistical significance after adjusting for confounders. RCS analysis found no significant nonlinear relationship (P > 0.05). ROC analysis showed that combining Cys-C and MHR modestly improved diagnostic accuracy (AUC = 0.6622, 95% CI: 0.554-0.77). Subgroup analysis indicated that severe OSA patients with hypertension had higher Cys-C and MHR levels compared to those without hypertension, though the differences were not statistically significant (P > 0.05).

Conclusions

Cys-C and MHR are positively associated with OSA severity, with MHR emerging as a stronger independent biomarker. Incorporating these markers into OSA risk stratification may enhance clinical assessment and targeted interventions. Future large-scale prospective studies are needed to validate their prognostic value and clinical utility.

Effects of continuous positive airway pressure on renal function in adults with obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

Obstructive sleep apnea (OSA) is associated with increased risk of chronic kidney disease (CKD). OSA is highly prevalent among patients with CKD, suggesting a bidirectional link between the two conditions. Recent studies reported that continuous positive airway pressure (CPAP) may benefit renal function in OSA patients; however, uncertainties regarding their effects persist. Therefore, we examined the effects of CPAP treatment on renal function in adults with OSA.

METHODS

We systematically searched PubMed, EMBASE, Cochrane Library, Web of Science, and ClinicalTrials.gov for relevant studies from their inception until January 2024. Pooled estimates for all outcomes were calculated using a random-effects model. Primary outcome measures were the estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR).

RESULTS

Four randomized controlled trials (RCTs) and seven non-RCTs (NRCTs) (n = 2,660) were included. Compared with the control group, the CPAP group exhibited a significantly minimal alleviation in eGFR decline in NRCT (mean difference [MD] = 1.95, 95% confidence interval [CI] = 0.80 to 3.11, p < 0.001), but not in RCT (MD = 1.42, 95% CI = - 0.99 to 3.82, p = 0.25). No significant associations were found between CPAP therapy and UACR (MD = - 0.05, 95% CI = - 0.41 to 0.30, p = 0.77).

CONCLUSION

Current research provides a low to moderate certainty of evidence, suggesting that CPAP therapy has little to no effect on alleviating the decline in renal function. However, further RCTs with larger sample sizes and extended follow-up periods are required.

Association between elevated cystatin C levels and obstructive sleep apnea hypopnea syndrome: a systematic review and updated meta-analysis

OBJECTIVE

This study seeks to elucidate variances in cystatin C levels between patients with Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) and controls while also assessing the impact of cystatin C on cardiovascular and cerebrovascular complications in patients with OSAHS. Furthermore, the benefits of surgery or continuous positive airway pressure (CPAP) treatment in reducing cystatin C levels in patients with OSAHS were explored.

METHODS

A thorough search was undertaken across various medical databases, namely PubMed, CNKI, EMBASE, Web of Science, and WanFang, until October 1, 2024, to determine published articles pertinent to OSAHS. The present research conducted a comprehensive review of the literature concerning cystatin C levels in both patients with OSAHS and controls, variations in cystatin C levels pre-and post-surgery/CPAP treatment, the Pearson/Spearman correlation coefficients between cystatin C levels and sleep monitoring indices, and the hazard ratio (HR) associated with cystatin C levels concerning the onset of cardiovascular and cerebrovascular diseases among patients with OSAHS. Meta-analyses were executed utilizing standardized mean difference (SMD) and correlation coefficients (COR) as effect variables. A fixed-effect model was utilized in cases where heterogeneity was not significant (I2 < 50%). Otherwise, a random-effect model was employed. Statistical analysis was executed utilizing STATA 11.0, GraphPad Prism 8, and R 4.1.3.

RESULTS

Forty articles were included in the final analysis. The serum/plasma cystatin C levels in the OSAHS group were significantly increased relative to the controls (SMD = 0.65, 95%CI: 0.50-0.79, P < 0.001). Subgroup analysis considering mean body mass index (BMI), mean age, ethnicity, and study design type consistently showed significantly elevated serum/plasma cystatin C levels in the OSAHS category relative to the controls. CPAP treatment can significantly decrease serum/plasma cystatin C levels in patients with OSAHS. Moreover, the increase in cystatin C levels may serve as a risk factor for stroke and MACC in patients with OSAHS. Serum/plasma cystatin C levels exhibited a positive correlation with AHI scores and ODI.

CONCLUSION

Elevated cystatin C levels in patients with OSAHS may pose a risk for the onset of cardiovascular and cerebrovascular diseases. Furthermore, cystatin C levels could serve as a valuable clinical indicator for evaluating treatment effectiveness and severity of OSAHS.

CLINICAL TRIAL NUMBER

Not applicable.

A meta-analysis of the correlation between obstructive sleep apnea syndrome and renal injury

OBJECTIVE

To conduct a meta-analysis on the correlation between obstructive sleep apnea syndrome (OSAS) and renal injury.

METHODS

Literature search was carried out in PubMed, Embase and Ovid-Medline databases between the date of database establishment and June 30th 2024. The keywords included obstructive sleep apnea hypopnea syndrome, sleep apnea hypopnea syndrome, renal injury, and correlation. Two researchers 1st independently screened the titles and abstracts based on the eligibility criteria, then extracted the data and evaluated the quality, and used Review Manager 5.3 for data processing. All analysis methods were based on PRISMA.

RESULTS

Finally, 8 studies that matched the inclusion criteria were included, and the relationship between obstructive sleep apnea syndrome and serum cystatin C was analyzed. The homogeneity test showed (P < 0.01, I2 = 98%), and from the meta-analysis results, it could be known that the level of serum cystatin C in sufferers with OSAS was obviously greater than the control one (OR = 1.12, 95% CI 0.96-1.28, P < 0.01). The relationship between OSAS and serum creatinine was analyzed, and homogeneity test showed (P < 0.01, I2 = 96%). From the meta analysis result, it could be known that the serum creatinine level of obstructive sleep apnea syndrome was obviously greater than the control one (OR = 1.01, 95% CI 0.85 ~ 1.17, P < 0.01). The relationship between obstructive sleep apnea syndrome with serum urea nitrogen was analyzed, and homogeneity test showed (P < 0.01, I2 = 91%). From the meta-analysis results, it could be known that serum urea nitrogen of OSAS was obviously greater than the control one (OR = 1.38, 95% CI 01.17 ~ 1.59, P < 0.01).

CONCLUSIONS

Eight articles have been included to determine the correlation between obstructive sleep apnea syndrome and renal injury, and it has been found that obstructive sleep apnea syndrome is closely related to renal injury, and the two may be risk factors for each other.

Pyroptosis: An Accomplice in the Induction of Multisystem Complications Triggered by Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common respiratory disorder, primarily characterized by two pathological features: chronic intermittent hypoxia (CIH) and sleep deprivation (SD). OSA has been identified as a risk factor for numerous diseases, and the inflammatory response related to programmed cell necrosis is believed to play a significant role in the occurrence and progression of multisystem damage induced by OSA, with increasing attention being paid to pyroptosis. Recent studies have indicated that OSA can elevate oxidative stress levels in the body, activating the process of pyroptosis within different tissues, ultimately accelerating organ dysfunction. However, the molecular mechanisms of pyroptosis in the multisystem damage induced by OSA remain unclear. Therefore, this review focuses on four major systems that have received concentrated attention in existing research in order to explore the role of pyroptosis in promoting renal diseases, cardiovascular diseases, neurocognitive diseases, and skin diseases in OSA patients. Furthermore, we provide a comprehensive overview of methods for inhibiting pyroptosis at different molecular levels, with the goal of identifying viable targets and therapeutic strategies for addressing OSA-related complications.

Triglyceride-glucose index and obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) has a bidirectional association with metabolic syndrome, and insulin resistance (IR). The triglyceride-glucose (TyG) index could be a simply calculated marker of IR in OSA. However, its clinical application appears still limited. Hence, this systematic review and meta-analysis aimed to respond to this question by analyzing all the existing studies showing an association between OSA and the TyG index.

METHODS

Four online databases, including PubMed, Scopus, the Web of Science, and Embase were searched for studies evaluating the TyG index in OSA. After screening and data extraction, a random-effect meta-analysis was performed to compare the TyG index in OSA patients vs. healthy controls by calculating standardized mean difference (SMD) and 95% confidence interval (CI) and pooling the area under the curves (AUCs) for diagnosis of OSA based on this index.

RESULTS

Ten studies involving 16,726 individuals were included in the current systematic review. Meta-analysis indicated that there was a significantly higher TyG index in patients with OSA, compared with the healthy controls (SMD 0.856, 95% CI 0.579 to 1.132, P < 0.001). Also, TyG had a diagnostic ability for OSA representing a pooled AUC of 0.681 (95% CI 0.627 to 0.735). However, based on the two studies' findings, no difference between different severities of OSA was observed. Finally, our data showed that the TyG index is a good potential predictor of adverse outcomes in these patients.

CONCLUSION

Our study revealed that the TyG index is an easy-to-measure marker of IR for assessing OSA, both in diagnosis and prognosis. Our study supports its implementation in routine practice to help clinicians in decision-making and patient stratification.

Meta-analysis of the effects of CPAP therapy on estimated glomerular filtration rate in patients with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is highly prevalent in patients with chronic kidney disease and may lead to a loss of kidney function. However, it remains unclear whether or not continuous positive airway pressure (CPAP) treatment improves the estimated glomerular filtration rate (eGFR) in patients with OSA. This meta-analysis was designed to investigate the effect of CPAP therapy on eGFR in patients with OSA.

METHODS

We searched the electronic databases Web of Science, Cochrane Library, PubMed, and Embase through June 1, 2022. Information about patients, CPAP duration, gender distribution, pre- and post-CPAP treatment eGFR, and age of patients were collected for further analysis. We applied the standardized mean difference (SMD) with a 95%confidence interval (CI) to analyze the pooled effects. Both Stata 12.0 software and Review Manager 5.2 software were employed for all statistical analyses.

RESULTS

A sample of 13 studies with 519 patients was included in the meta-analysis. There was no significant change of eGFR levels before and after CPAP usage for patients with OSA (SMD =  - 0.05, 95%CI: - 0.30 to 0.19, Z = 0.43, p = 0.67). However, subgroup analysis revealed that the level of eGFR was obviously decreased after CPAP therapy in patients with OSA and CPAP use duration > 6 months (SMD =  - 0.30, 95% CI =  - 0.49 to - 0.12, z = 3.20, p = 0.001), and elderly patients (> 60 years) (SMD =  - 0.32, 95% CI =  - 0.52 to - 0.11, z = 3.02, p = 0.002).

CONCLUSIONS

Meta-analysis confirmed that OSA treatment with CPAP has no clinically significant effect on eGFR.

High nocturnal periodic breathing reported by PAP adherence data predicts decompensation of heart failure

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) often coexists with heart failure (HF) and is commonly treated with positive airway pressure (PAP) therapy. Periodic breathing (PB) may be present in HF and is an indicator of poor prognosis, but there is no easy way to detect PB in an outpatient setting. However, it can be detected by analyzing PAP usage data. The study aimed to assess if high PB% detected by PAP machine could predict impending HF exacerbation and if better PAP adherence is associated with reduced hospitalization and mortality.

METHODS

We retrospectively reviewed medical records of 115 patients with OSA from the sleep clinic of our VA Medical Center. The cross-sectional data on demographics, labs, PAP adherence, PB% in the previous 30 days, echocardiogram in the previous 6 months, and hospitalizations and mortality in the subsequent 180 days were extracted. Based on left ventricular ejection fraction (LVEF), patients were classified into (1) HF with normal-midrange LVEF (LVEF ≥40%, n = 74) and (2) HF with reduced LVEF (LVEF < 40%, n = 41). Pairwise correlation and linear regressions were done to assess predictors of PB%. Binomial and logistic regressions assessed the relationship of PB% and PAP adherence with hospitalization from HF and all-cause mortality.

RESULTS

In the HF with reduced LVEF group, the mean PB% was 2.6 times higher (P < .001) and PAP adherence was 29% lower (P < .001). PB% positively correlated with brain natriuretic peptide level (r = .447, P < .01) and number of hospitalizations (r = .331, P < .01). Higher PB% negatively correlated with LVEF (r = -.423, P < .01) and estimated glomerular filtration rate (r = -.246, P < .01). Every 10% increase in PAP adherence decreased odds of hospitalization by 0.78 times (P < .001) and odds of death by 0.86 (P = .043).

CONCLUSIONS

High PB% detected by PAP machine data is a predictor of impending HF exacerbation and hospitalization. Improved PAP adherence and optimization of medical therapy may reduce hospitalization and all-cause mortality.

CITATION

Ullah MI, Tamanna S, Bhagat R. High nocturnal periodic breathing reported by PAP adherence data predicts decompensation of heart failure. J Clin Sleep Med. 2023;19(3):431-441.

Inflammasome Activation: A Keystone of Proinflammatory Response in Obstructive Sleep Apnea

RATIONALE

As the mechanism that links obstructive sleep apnea (OSA) with the regulation of inflammatory response is not well known, it is important to understand the inflammasome activation, mainly of nucleotide-binding oligomerization domain-like receptor 3 (NLRP3).

OBJECTIVES

To assess the NLRP3 activity in severe OSA patients and to identify its role in the systemic inflammatory response of OSA patients.

METHODS

We analyzed the NLRP3 activity as well as key components of the inflammasome cascade, such as adaptor molecule apoptosis-associated speck-like protein (ASC), caspase-1, Gasdermin D (GSDMD), interleukin (IL)-1β, IL-18 and tissue factor (TF), in monocytes and plasma from patients with severe OSA and non-apneic healthy subjects. We explored the association of the different key markers with inflammatory comorbidities.

MAIN RESULTS

Monocytes from patients with severe OSA presented higher NLRP3 activity than those from non-apneic control subjects, which directly correlated with the apnea-hypopnea index and hypoxemic indices. NLRP3 over-activity triggered inflammatory cytokines (Il-1β and IL-18) via caspase-1 and increased Gasdermin D, allowing for tissue factor to be released. In vitro models confirmed that monocytes increase NLRP3 signaling under intermittent hypoxia (IH) in an HIF-1α-dependent manner, and/or in combination with plasma from OSA patients. Plasma levels of TF were higher in OSA patients with systemic inflammatory comorbidities than in those without them.

CONCLUSIONS

In severe OSA patients, NLRP3 activation might be a linking mechanism between intermittent hypoxia and other OSA-induced immediate changes with the development of systemic inflammatory response.

Is kidney a new organ target in patients with obstructive sleep apnea? Research priorities in a rapidly evolving field

The bidirectional relationship between sleep disordered breathing and chronic kidney disease (CKD) has recently gained a lot of interest. Several lines of evidence suggest the high prevalence of coexistent obstructive sleep apnea (OSA) in patients with CKD and end-stage renal disease (ESRD). In addition, OSA seems to result in loss of kidney function in some patients, especially in those with cardio-metabolic comorbidities. Treatment of CKD/ESRD and OSA can alter the natural history of each other; still better phenotyping with selection of appropriate treatment approaches is urgently needed. The aim of this narrative review is to provide an update of recent studies on epidemiological associations, pathophysiological interactions, and management of patients with OSA and CKD or ESRD.

Sleep Apnea and the Kidney

Purpose of Review

There are some uncertainties about the interactions between obstructive sleep apnea (OSA) and chronic kidney disease (CKD). We critically reviewed recent studies on this topic with a focus on experimental and clinical evidence of bidirectional influences between OSA and CKD, as well as the effects of treatment of either disease.

Recent Findings

Experimental intermittent hypoxia endangers the kidneys, possibly through activation of inflammatory pathways and increased blood pressure. In humans, severe OSA can independently decrease kidney function. Treatment of OSA by CPAP tends to blunt kidney function decline over time, although its effect may vary. OSA may increase cardiovascular complications and mortality in patients with end-stage renal disease (ESRD), while it seems of little harm after renal transplantation. Excessive fluid removal may explain some of the improvements in OSA severity in ESRD and after transplantation.

Summary

Severe OSA and CKD do interact negatively, mainly through hypoxia and fluid retention. The moderate mutually interactive benefits that treatment of each disease exerts on the other one warrant further studies to improve patient management.