Association of diagnosed obstructive sleep apnea with kidney transplant outcomes

Sleep-Related Disorders in Patients with CKD and Kidney Transplant Recipients

Sleep disorders such as insomnia, restless legs syndrome (RLS), and sleep apnea (SA) are common in patients with CKD. These conditions tend to become more prevalent and more severe as kidney function deteriorates and when a patient reaches ESKD. The prevalence of insomnia in the general population ranges from 4% to 29% compared with ( 1 ) 30%-67%, ( 2 ) 39%-54%, ( 3 ) 41%-79%, and ( 4 ) 9%-49% in patients with CKD, on hemodialysis, on peritoneal dialysis (PD), or in kidney transplant recipients (KTRs), respectively. RLS occurs in approximately 1%-15% of the general population compared with ( 1 ) 5%-18%, ( 2 ) 24%-33%, ( 3 ) 23%-64%, and ( 4 ) 6%-8% in patients with CKD, on hemodialysis, on PD, or in KTRs, respectively. Obstructive SA has been reported in ( 1 ) 40%-69%, ( 2 ) 25%-47%, ( 3 ) 9%-52%, and ( 4 ) 25%-30% in patients with CKD, on hemodialysis, on PD, or in KTRs, respectively. Fatigue is a complex symptom that has been reported in patients with CKD, ESKD, and in KTRs and can be associated with sleep disorders. Fatigue and sleep disorders have been associated with negative outcomes such as progression of CKD, increased risk of morbidity, mortality, and lower health-related quality of life. In this review, we highlight nonpharmacologic and pharmacologic options for treatment of these sleep disorders. Specifically, the diagnosis and evaluation, epidemiology, risk factors and associations, outcomes (such as CKD progression, morbidity, and mortality), treatment, and post-transplant outcomes for sleep disorders (insomnia, RLS, and SA) and fatigue will be discussed.

Sleep-related breathing disorders and cardiometabolic risk factors in pediatric kidney transplant recipients

BACKGROUND

SRBDs have been shown to increase the risk of cardiovascular disease, which is a significant cause of mortality in kidney transplant recipients. Few studies have investigated the association between SRBDs and cardiometabolic risk factors in pediatric kidney transplant recipients.

METHODS

This was a cross-sectional study of pediatric kidney transplant recipients using baseline cardiometabolic data from a previous clinical trial (NCT01007994). Parents/guardians of pediatric kidney transplant recipients filled out 22-item PSQ. A score greater than 33% was defined as a diagnosis of a SRBD. Fisher's exact test, Mann-Whitney U test, and regressions were used to determine associations.

RESULTS

Among the 58 transplant recipients enrolled, 14.80% (n = 8) of participants identified as Black and 40.7% (n = 22) were male. The median age was 13 (IQR 8.25, 17) years and median number of years post-transplant for participants was 2 (IQR 1, 4). The prevalence of SRBDs was 26% (n = 14). The presence of a SRBD was associated with abnormalities in multiple cardiometabolic risk factors including total cholesterol level (β = 23.63; 95% CI 3.58-43.67), LDL level (β = 24.94; 95% CI 6.37-43.50), triglyceride level (β = 54.62; 95% CI 8.74-100.50), and LVH (OR = 5.12; 95% CI 1.12-23.45) when adjusted for age, sex, and race.

CONCLUSIONS

Similar to associations reported in the general pediatric and general CKD populations, SRBD is associated with increased cardiometabolic risk in pediatric kidney transplant recipients.

Sudden death in individuals with obstructive sleep apnoea: a systematic review and meta-analysis

Objectives

Over 1 billion individuals worldwide experience some form of sleep apnoea, and this number is steadily rising. Obstructive sleep apnoea (OSA) can negatively influence one’s quality of life and potentially increase mortality risk. However, the association between OSA and mortality has not been reliably estimated. This meta-analysis estimates the risk of all-cause and cardiovascular mortality in individuals with OSA.

Design

Systematic review and meta-analysis.

Data sources

MEDLINE, Cochrane Library, Scopus and Joanna Briggs Institute Evidence-Based Practice databases were searched from inception through 1 January 2020.

Eligibility criteria for selecting studies

We included observational studies assessing the association of sudden deaths in individuals with and without OSA.

Data extraction and synthesis

Two independent reviewers (AES and ESH) extracted data and assessed the risk of bias using the Newcastle-Ottawa Scale quality assessment tool. Data were pooled using the random-effects models and reported as risk ratios (RRs) with 95% CIs. Heterogeneity was quantified with I² statistic.

Results

We identified 22 observational studies (n=42 099 participants). The mean age was 62 years and 64% were men. OSA was associated with all-cause sudden death (RR=1.74, 95% CI: 1.44 to 2.10, I²=72%) and cardiovascular mortality (RR=1.94, 95% CI: 1.39 to 2.70, I²=32%). A marginally significant dose–response relationship between severity of OSA and the risk of death was observed (p for interaction=0.05): mild OSA (RR=1.16, 95% CI: 0.70 to 1.93), moderate OSA (RR=1.72, 95% CI: 1.11 to 2.67) and severe OSA (RR=2.87, 95% CI: 1.70 to 4.85). Meta-regression analysis showed that older age was a significant contributing factor in the relationship between OSA and mortality. The median study methodological quality was considered high.

Conclusions

OSA is a significant risk factor for all-cause mortality and cardiac mortality. Prevention and treatment strategies to optimise survival and quality of life in individuals with OSA are urgently needed.

PROSPERO registration number

CRD42020164941.

Sleep Apnea as a Cardiorenal Risk Factor in CKD and Renal Transplant Patients

BACKGROUND

Chronic kidney disease (CKD) is a public health priority of increasing concern worldwide. Sleep apnea (SA) of moderate-to-severe degree has a 3-9% prevalence in women and 10-17% in men in the general population.

SUMMARY

In CKD patients, the prevalence of SA parallels the decline of the GFR being 27% in CKD patients with a GFR of >60 mL/min/1.73 m2 and 57% in patients with end-stage kidney disease (ESKD). In the early CKD stages, fluid overload is probably the sole risk factor for SA in this population. At more severe CKD stages, disturbed central and peripheral chemosensitivity and the accumulation of uremic toxins might contribute to SA. Still, there is no direct evidence supporting this hypothesis in human studies. Observational studies coherently show that SA is a risk factor for CKD incidence and CKD progression as well as for cardiovascular disease and death in this population. However, there is no randomized clinical trial testing continuous positive airway pressure or other interventions documenting that attenuation of SA may have a favorable effect on renal and cardiovascular outcomes in CKD and ESKD patients. However, most likely, the causal nature of the association between SA and cardiorenal outcomes remains unproven. Renal transplantation is the most effective treatment of SA in patients with ESKD, but this disturbance re-emerges on long-term observation in this population. However, after renal transplantation, SA does not seem to be a predictor of adverse health outcomes.

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.