Renal functions in obstructive sleep apnea patients

The relationship between obstructive sleep apnea and risk of renal impairment in patients with hypertension, a longitudinal study

OBJECTIVE

Association of obstructive sleep apnea (OSA) with renal damage is undetermined, especially in the population with hypertension, a high-risk group for chronic kidney disease. Therefore, we aimed to explore whether OSA is an independent risk factor for renal impairment in patients with hypertension, by considering the effects of gender, age, obesity and OSA severity.

METHODS

The longitudinal observational study included patients with hypertension and suspected OSA without renal damage at baseline who visited Hypertension Center between January 2011 and December 2018, and followed up till renal outcomes, death, loss to follow-up, or May 31, 2022, using annual health check-ups, hospital readmission or out-patient visits. Main renal outcome was chronic kidney disease (CKD), defined as estimated glomerular filtration rate <60 ml/min per 1.73 m2 and/or positive proteinuria. Cox proportional hazard models were used to evaluate the association, and repeated after propensity score matching. Sensitivity analysis were performed by excluding those with primary aldosteronism.

RESULTS

7961 patients with hypertension were included with 5022 ones with OSA, and 82% were followed up. During median follow-up of 3.42 years, 1486 patients developed CKD. Per 1000 person-year incidence of CKD was 56.72 in OSA group. In Cox regression analysis, OSA and severe OSA group respectively showed 1.21 (95% CI: 1.08-1.35) and 1.27 (95% CI: 1.09-1.47) fold risk for CKD in total, compared with non-OSA group. Overall results remained consistent in propensity score matching and sensitivity analysis.

CONCLUSION

OSA is independently associated with higher risk of chronic kidney disease in hypertension.

Impact of Pulmonary Hypertension on Renal Functions in Obstructive Sleep Apnea Syndrome

OBJECTIVES

Pulmonary hypertension (PH) is common in obstructive sleep apnea syndrome (OSAS). This study aimed to evaluate the effect of PH on kidney functions in patients with OSAS.

METHODS

The data of patients who were diagnosed as having OSAS after referral to the sleep center in the Gaziantep University Medical Faculty between January 2005 and June 2017 were evaluated. The estimated glomerular filtration rate was calculated with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Renal functions of the subjects who had data after 5 years were included for long-term analysis.

RESULTS

A total of 2152 patients with OSAS (n = 1540), PH (n = 49), OSAS and PH coexistence (n = 359), and the control group (n = 204) were included in the study. Pulmonary arterial pressure (PAP) was 44.51 ± 23.73 in the PH group; it was 37.1 ± 13.14 in the group with OSAS + PH (P = 0.001) Urea and uric acid were found to be higher in the association of OSAS + PH. CKD-EPI was lower in the presence of PH or OSAS + PH than in the presence of OSAS. PH was present in 16.06% of males and 25.10% of females (P = 0.000), and PAP was detected as 35.80 ± 13.23 and 40.96 ± 16.65, respectively (P = 0.001). PH was present in 15.99% of males and 25.84% of females with OSAS (P = 0.000). The PAP of males with OSAS was 36.03 ± 13.46, and the PAP of females was 38.68 ± 12.55 (P = 0062). Urea, creatinine, and uric acid were higher and CKD-EPI was lower in male subjects in the presence of OSAS and PH, whereas the same scenario also was present in the presence of PH alone in female subjects. Long-term comparisons (n = 343) revealed significant decreases in the CKD-EPI in those with OSAS and OSAS + PH and these decrease were more pronounced in the presence of OSAS and PH. The regression analysis revealed that female patients had lower CKD-EPI in the presence of PH, although the presence of PH had no effect on CKD-EPI in males.

CONCLUSIONS

PH is a risk factor for the deterioration of renal function in OSAS and more prominent in the long term.

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.

Bidirectional association between chronic kidney disease and sleep apnea: a systematic review and meta-analysis

BACKGROUND

Previous data have suggested a link between chronic kidney disease (CKD) and sleep apnea (SA). However, the prevalence and risk association of both disease entities are not uniformly described.

METHODS

Ovid MEDLINE, EMBASE, and the Cochrane Library were searched for eligible publications that included patients aged ≥ 18 years diagnosed with CKD or SA. Included studies were divided into two cohorts: (1) a cohort of CKD or end-stage kidney disease (ESKD) patients reporting the prevalence of SA or odds ratio (OR) for SA (CKD cohort) and (2) a cohort of SA patients reporting the prevalence of CKD/ESKD or OR for CKD/ESKD (SA cohort).

RESULTS

CKD cohort: Of 16 studies (n = 340,587), the pooled estimated prevalence of SA among CKD/ESKD patients was 47.5% (95% CI 28.8-66.9). The pooled adjusted OR for SA among CKD/ESKD patients was 1.961 (95% CI 1.702-2.260). Male sex, history of diabetes, and lower BMI were associated with increased prevalence of SA. SA cohort: Of 12 studies (n = 3,103,074), the pooled prevalence of CKD/ESKD among patients with SA was 8.2% (95% CI 4.7-13.7), whereas the pooled adjusted OR for CKD/ESKD among patients with SA was 2.088 (95% CI 1.777-2.452). Increasing age, higher BMI, male sex, white race, and history of diabetes were associated with higher prevalence of CKD/ESKD.

CONCLUSION

There was a bidirectional association between CKD/ESKD and SA. Interventions aiming to prevent the progression of either CKD or SA are important.

Obstructive sleep apnea syndrome and risk of renal impairment: a systematic review and meta-analysis with trial sequential analysis

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with a variety of systemic diseases. Among patients with chronic kidney diseases (CKD), the prevalence of OSAS is high. OSAS can induce progression of CKD. However, whether or not OSAS can cause renal damage in healthy people is not clear. Thus, the purpose of this meta-analysis was to elucidate whether or not there was an association between OSAS and early renal damage.

METHODS

PubMed, Embase Database, Cochrane Library, Web of Science, China National Knowledge Infrastructure, China Biology Medicine Database, Chinese Scientific Journals Database, and Wanfang Database were searched systematically. The relative risk (RR), weighted mean difference (WMD), and 95% confidence intervals (CI) were used to evaluate the relationship between OSAS and early renal damage. Funnel plot and Egger's test were used to evaluate publication bias, and trial sequential analysis (TSA) was employed to verify the sufficiency of the research conclusions.

RESULTS

A total of 18 studies were analyzed comprising 4,567 participants. Compared with the healthy control group, levels of cystatin C (MD = 0.530, 95% CI 0.423, 0.637, P < 0.01) and proteinuria in patients with OSAS were significantly increased, while the levels of estimated glomerular filtration rate (eGFR) (MD = - 0.194, 95% CI - 0.268, - 0.121, P < 0.01) were significantly decreased. Furthermore, patients with OSAS also had an increased risk of CKD. Subgroup analysis showed that compared with patients without OSAS, the level of serum cystatin C in patients with OSAS was significantly increased independent of hypertension and diabetes, and the eGFR was significantly decreased in patients with moderate to severe OSAS and comorbid hypertension and/or diabetes.

CONCLUSION

In this meta-analysis, OSAS was associated with a higher risk of early renal damage. Patients with OSAS and comorbid hypertension and/or diabetes appear to suffer from severe renal damage.

Association of serum adiponectin level with cystatin C in male patients with obstructive sleep apnea syndrome

PURPOSE

Obstructive sleep apnea syndrome (OSAS) was suggested to exert an effect on renal function. However, the specific mechanism was still unknown. We try to find the association among OSAS, adiponectin, and cystatin C and the effect of adiponectin on renal function in OSAS patients.

METHODS

Seventeen healthy men and seventy-three men which only had OSAS were included in the end. Apnea-hypopnea index (AHI), oxygen desaturation index (ODI), the percentage of total sleep time spent with SpO₂ < 90% (T90%), lowest O₂ saturation (LaSO₂), Epworth Sleepiness Scale (ESS) score, serum adiponectin, and high-sensitive C-reactive protein (hsCRP) were detected in all subjects, and renal function was evaluated with creatinine, cystatin C, and estimated glomerular filtration rate (eGFR).

RESULTS

Demographic data, creatinine, and eGFR did not differ among the studied groups. Decreased serum adiponectin levels were associated with severe OSAS. OSAS patients had a higher hsCRP and cystatin C than those without OSAS. Serum adiponectin levels had a negative association with cystatin C. After adjusted for confounders, adiponectin, hsCRP, and ODI had a significant prediction on the cystatin C (β = - 0.218, p = 0.011; β = 0.226, p = 0.037; and β = 0.231, p = 0.029).

CONCLUSIONS

Decreased serum adiponectin was associated with increased cystatin C in male OSAS patients. These results suggest that serum adiponectin might be a regulatory factor for renal function in OSAS.

Chronic kidney disease in patients with obstructive sleep apnea. A narrative review

Prevalence of both chronic kidney disease (CKD) and obstructive sleep apnea (OSA) is continuously increasing. Moreover, the prevalence of OSA increases as kidney function declines and is higher among patients with end-stage renal disease (ESRD). In addition, OSA is recognized as a potential nontraditional risk factor for development and progression of CKD. Continuous positive airway pressure (CPAP) plays a pivotal role in the management of OSA, eliminating patients' symptoms and improving their quality of life. Recent studies suggested that CPAP treatment may have beneficial effects on kidney function among patients with OSA. This narrative review summarizes the existing knowledge on the association between CKD and OSA, with emphasis on the epidemiology, the pathophysiology of the development of CKD in OSA and vice versa, as well as the effect of CPAP on renal function.

The association of obstructive sleep apnea and renal outcomes-a systematic review and meta-analysis

BACKGROUND

The aim of this systematic review and meta-analysis was to summarize the association of obstructive sleep apnea (OSA) with renal outcome.

METHODS

Our study followed the PRISMA guidelines. Two independent reviewers searched for relevant articles in the databases of Pubmed, the Web of Science and CENTRAL, and conducted study selection and quality assessment. A random-effect model was used to estimate the effects.

RESULTS

total of 1240 articles were initially identified (Pubmed = 568, Web of Science = 640, CENTRAL = 32). After removal of duplicate articles (n = 415) and irrelevant articles (n = 788), 37 were selected for full-text review, and 18 were finally included in the analysis. Overall, patients diagnosed with OSA were found to have a higher odds ratio (OR) of a poorer renal outcome, with a pooled OR of 1.77 (95% C.I.: 1.37–2.29). The significant association between OSA and a poorer renal outcome was not affected by the medical condition of diabetes mellitus (DM). In addition, we found that OSA was consistently associated with higher albuminuria/proteinuria and a lower estimated glomerular filtration rate (eGFR), with a pooled OR of 1.84 (95% C.I.: 1.24–2.73) and 1.60 (95% C.I.: 1.19–2.16), respectively. A greater OSA severity was also found to be related to a higher OR, with a mild group OR of 1.45 (95% C.I.: 1.19–1.77) and a moderate and severe group OR of 2.39 (95% C.I.: 1.96–2.90).

CONCLUSIONS

Our study demonstrated that OSA is significantly associated with poorer renal function.

Genome-wide gene expression array identifies novel genes related to disease severity and excessive daytime sleepiness in patients with obstructive sleep apnea

We aimed to identify novel molecular associations between chronic intermittent hypoxia with re-oxygenation and adverse consequences in obstructive sleep apnea (OSA). We analyzed gene expression profiles of peripheral blood mononuclear cells from 48 patients with sleep-disordered breathing stratified into four groups: primary snoring (PS), moderate to severe OSA (MSO), very severe OSA (VSO), and very severe OSA patients on long-term continuous positive airway pressure treatment (VSOC). Comparisons of the microarray gene expression data identified eight genes up-regulated with OSA and down-regulated with CPAP treatment, and five genes down-regulated with OSA and up-regulated with CPAP treatment. Protein expression levels of two genes related to endothelial tight junction (AMOT P130, and PLEKHH3), and three genes related to anti-or pro-apoptosis (BIRC3, ADAR1 P150, and LGALS3) were all increased in the VSO group, while AMOT P130 was further increased, and PLEKHH3, BIRC3, and ADAR1 P150 were all decreased in the VSOC group. Subgroup analyses revealed that AMOT P130 protein expression was increased in OSA patients with excessive daytime sleepiness, BIRC3 protein expression was decreased in OSA patients with hypertension, and LGALS3 protein expression was increased in OSA patients with chronic kidney disease. In vitro short-term intermittent hypoxia with re-oxygenation experiment showed immediate over-expression of ADAR1 P150. In conclusion, we identified a novel association between AMOT/PLEKHH3/BIRC3/ADAR1/LGALS3 over-expressions and high severity index in OSA patients. AMOT and GALIG may constitute an important determinant for the development of hypersomnia and kidney injury, respectively, while BIRC3 may play a protective role in the development of hypertension.

Emerging co-morbidities of obstructive sleep apnea: cognition, kidney disease, and cancer

Obstructive sleep apnea (OSA) causes daytime fatigue and sleepiness, and has an established relationship with cardiovascular and metabolic disease. Recent years have seen the emergence of an evidence base linking OSA with an increased risk of degenerative neurological disease and associated cognitive impairment, an accelerated rate of decline in kidney function with an increased risk of clinically significant chronic kidney disease (CKD), and with a significantly higher rate of cancer incidence and death. This review evaluates the evidence base linking OSA with these seemingly unrelated co-morbidities, and explores potential mechanistic links underpinning their development in patients with OSA, including intermittent hypoxia (IH), sleep fragmentation, sympathetic excitation, and immune dysregulation.

An update on cardiovascular effects of obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome is an important health problem which may cause or worsen systemic diseases. Chronic intermittent hypoxia during repetitive airflow cessations may cause endothelial dysfunction. Sleep apnoea is also shown to be associated with hypercoagulability which may be due to decreased nitric oxide levels and impaired vasodilatation. Endothelial dysfunction, increased systemic inflammation, sympathetic nervous system activation, increased oxidative stress and dysglycaemia may all contribute to cardiovascular processes such as hypertension, arrhythmia, stroke, heart failure and coronary artery disease in patients with obstructive sleep apnoea. Treatment approaches in patients with obstructive sleep apnoea mainly focus on maintaining upper airway patency either with positive airway pressure devices or upper airway appliances. Strategies involving positive airway pressure therapy are associated with decreased morbidity and mortality. Obstructive sleep apnoea should be suspected as an underlying mechanism in patients with cardiovascular disease and warrants appropriate treatment.

Kidney-lung connections in acute and chronic diseases: current perspectives

Lung and kidney functions are intimately related in both health and disease. The regulation of acid-base equilibrium, modification of partial pressure of carbon dioxide and bicarbonate concentration, and the control of blood pressure and fluid homeostasis all closely depend on renal and pulmonary activities. These interactions begin in fetal age and are often responsible for the genesis and progression of diseases. In gestational age, urine is a fundamental component of the amniotic fluid, acting on pulmonary maturation and growth. Moreover, in the first trimester of pregnancy, kidney is the main source of proline, contributing to collagen synthesis and lung parenchyma maturation. Pathologically speaking, the kidneys could become damaged by mediators of inflammation or immuno-mediated factors related to a primary lung pathology or, on the contrary, it could be the renal disease that determines a consecutive pulmonary damage. Furthermore, non immunological mechanisms are frequently involved in renal and pulmonary diseases, as observed in chronic pathologies such as sleep apnea syndrome, pulmonary hypertension, progressive renal disease and hemodialysis. Kidney damage has also been related to mechanical ventilation. The aim of this review is to describe pulmonary-renal interactions and their related pathologies, underscoring the need for a close collaboration between intensivists, pneumologists and nephrologists.