Sleep apnea syndrome and restless legs syndrome in kidney transplant recipients

Sleep microstructure and clinical characteristics of patients with restless legs syndrome

STUDY OBJECTIVES

Restless legs syndrome (RLS) is a sleep-related movement disorder, often accompanied by sleep disruption. Obstructive sleep apnea (OSA) has a controversial prevalence among patients with RLS. We evaluated the clinical and sleep features of patients who attended our sleep clinic considering RLS and OSA.

METHODS

In this cross-sectional study, we obtained health records of 1,497 patients during 2015-2019 who underwent polysomnography (PSG). Baseline characteristics, sleep-related and RLS questionnaires, and sleep microstructure were assessed. Descriptive and analytical assessments were performed. RLS was assessed according to the International Restless Legs Syndrome Study Group criteria.

RESULTS

RLS was found in 19.4% of patients, with more prevalence among women (26.9% vs 16.4%). RLS affected 19.1% of patients with OSA. Patients with RLS were significantly older with higher insomnia and depression and worse PSG results. As the respiratory disturbance index increased, the odds of RLS slightly decreased (adjusted odds ratio [95% confidence interval]: 0.80 [0.67-0.94]). The odds of OSA (respiratory disturbance index ≥ 5) was not affected by RLS. OSA in patients with RLS was significantly associated with a higher limb movement index. RLS in patients with OSA was significantly associated with higher insomnia, depression, and limb movement index (men and women), higher wake after sleep onset and percentage of N1 sleep (men), and lower sleep efficiency (men).

CONCLUSIONS

Patients with RLS had worse PSG results, higher insomnia, and depression. Although men with OSA+/RLS+ had worsened PSG results, PSG parameters in women with OSA+/RLS+ did not differ from the OSA+/RLS- group. Patients with either OSA or RLS should be evaluated for possible comorbidities, including insomnia and depression. Notably, sex-specific characteristics need more consideration in sleep clinics.

CITATION

Amirifard H, Jameie M, Akbarpour S, et al. Sleep microstructure and clinical characteristics of patients with restless legs syndrome. J Clin Sleep Med. 2022;18(11):2653-2661.

Prevalence and Risk Factors of Restless Legs Syndrome in Hemodialysis Patients

OBJECTIVE

The current study aimed to investigate the prevalence and risk factors of restless legs syndrome (RLS) in patients undergoing hemodialysis, as well as the mortality and risks of cardiovascular and cerebrovascular events.

METHODS

A total of 354 hemodialysis patients from four hospitals were enrolled. RLS was diagnosed using the International RLS Study Group (IRLSSG) criteria. The patients were evaluated face-to-face using the IRLSSG rating scale, Epworth Sleepiness Scale (ESS), Hamilton Anxiety Scale, Hamilton Depression Scale, and Pittsburgh Sleep Quality Index (PSQI). The patients were followed up for 9 months. Death was considered an endpoint event. The cardiovascular and cerebrovascular events were investigated.

RESULTS

The prevalence of RLS in hemodialysis patients was 40.7% and was associated with factors such as duration of hemodialysis, hypersensitive C-reactive protein, hyperparathyroidism, glycosylated serum protein, and erythropoietin treatment. The scores of the PSQI, ESS, and Hamilton Depression Scale in the RLS group were significantly higher than those in the non-RLS group (p < 0.05). During follow-ups, the incidence rate of cardiovascular diseases was 18.8% in the RLS group and 8.6% in the non-RLS group (p < 0.005). The IRLSSG rating scores were significantly higher in RLS patients with kidney transplantation failure compared with those without transplantation (p < 0.05).

CONCLUSION

The prevalence of RLS was high in hemodialysis patients. The risk factors of RLS included duration of hemodialysis, hypersensitive C-reactive protein, hyperparathyroidism, glycosylated serum protein, and erythropoietin treatment. RLS affected sleep quality and emotion and increased the risk of cardiovascular diseases in hemodialysis patients. RLS was more severe in patients with kidney transplantation failure compared with those without transplantation.

Chronic Use of Proton-Pump Inhibitors and Iron Status in Renal Transplant Recipients

Proton-pump inhibitor (PPI) use may influence intestinal iron absorption. Low iron status and iron deficiency (ID) are frequent medical problems in renal transplant recipients (RTR). We hypothesized that chronic PPI use is associated with lower iron status and ID in RTR. Serum iron, ferritin, transferrin saturation (TSAT), and hemoglobin were measured in 646 stable outpatient RTR with a functioning allograft for ≥ 1 year from the "TransplantLines Food and Nutrition Biobank and Cohort Study" (NCT02811835). Median time since transplantation was 5.3 (1.8-12.0) years, mean age was 53 ± 13 years, and 56.2% used PPI. In multivariable linear regression analyses, PPI use was inversely associated with serum iron (β = -1.61, p = 0.001), natural log transformed serum ferritin (β = -0.31, p < 0.001), TSAT (β = -2.85, p = 0.001), and hemoglobin levels (β = -0.35, p = 0.007), independent of potential confounders. Moreover, PPI use was independently associated with increased risk of ID (Odds Ratio (OR): 1.57; 95% Confidence Interval (CI )1.07-2.31, p = 0.02). Additionally, the odds ratio in RTR taking a high PPI dose as compared to RTR taking no PPIs (OR 2.30; 95% CI 1.46-3.62, p < 0.001) was higher than in RTR taking a low PPI dose (OR:1.78; 95% CI 1.21-2.62, p= 0.004). We demonstrated that PPI use is associated with lower iron status and ID, suggesting impaired intestinal absorption of iron. Moreover, we found a stronger association with ID in RTR taking high PPI dosages. Use of PPIs should, therefore, be considered as a modifiable cause of ID in RTR.

The Prevalence of Sleep Apnea in Iran: a Systematic Review and Meta-Analysis

BACKGROUND

Sleep apnea is a common sleep disorder which is associated with cardiovascular diseases, diabetes and stroke. Different studies conducted in Iran have reported different prevalence for sleep apnea. The aim of the present study was to determine the prevalence of sleep apnea in Iran.

MATERIALS AND METHODS

In this study, 42 studies that have been published in Farsi and English languages were selected with no time limit up to the March of 2018. Article search was conducted using "prevalence", "frequency", "sleep apnea" and "obstructive sleep apnea" keywords in Scientific Information Database (SID), MagIran, Google Scholar, Science Direct, PubMed and Scopus databases. Data were analyzed using meta-analysis and random effect model methods. Heterogeneity between the studies was evaluated using I² test. Data were analyzed using Stata software version 11.2.

RESULTS

The total prevalence of metabolic syndrome was 44% (95% CI: 35% to 53%). The highest prevalence of sleep apnea distinguished by the disease belonged to patients with sleep disorders (74%, 95% CI: 66%-82%), diabetes mellitus (61%; 95% CI: 46%-76%) and cardiovascular disease (55%; 95% CI: 47%-63%).

CONCLUSION

Given high prevalence of sleep apnea in Iran, identifying people at risk and providing instructional materials for controlling and treating sleep apnea is necessary.