Sleep apnea-associated hypoxia and very short sleep are linked with a higher moderate-to-severe chronic kidney disease (CKD) prevalence when compared with “normal” sleep, explains Chandra L. Jackson, Ph.D., MS. “This relationship highlights the need for novel interventions,” she says. “However, although CKD affects approximately 15% of adults in the United States, there are several gaps in the existing literature regarding its association with poor sleep. Few studies have included multiple sleep characteristics, few include objectively measured sleep characteristics, most have relatively small sample sizes, and most did not include racially/ethnically diverse study participants.”
Pathways to CKD Include Preceding Conditions, Inflammation, & Hypoxia
For a study published in Thorax, Dr. Jackson and colleagues investigated the link between multiple objectively measured sleep dimensions and CKD. Poor sleep, she points out, may contribute to CKD through several pathways, including:
- preceding conditions, such as obesity, hypertension, and type 2 diabetes
- inflammation, oxidative stress, and systemic endothelial dysfunction
- hypoxia causing a rise in systemic and intraglomerular pressure
The study team conducted the study among 1,895 Multi-Ethnic Study of Atherosclerosis (MESA) Sleep Ancillary Study participants who completed in-home polysomnography, wrist actigraphy, and a sleep questionnaire. Using Poisson regression models with robust variance, they estimated separate prevalence ratios and 95% confidence intervals for moderate-to-severe CKD (glomerular filtration rate <60 mL/min/1.73 m2 or albuminuria >30 mg/g) among participants according to multiple sleep dimensions, including very short (≤5 hours) sleep, Apnea−Hypopnea Index, and sleep apnea-specific hypoxic burden (SASHB). Regression models were adjusted for sociodemographic characteristics, health behaviors, and clinical characteristics.
Of the total participants, the mean age was 68 years, 54% were women, 37% White, 28% Black, 24% Hispanic/Latinx, and 11% Asian. “CKD is not randomly distributed across the population,” Dr. Jackson says. “Racial and ethnic minorities in the US, especially Black Americans, disproportionally experience both CKD and poor sleep.” The study data indicate that certain sleep dimensions or disorders are associated with CKD, Dr. Jackson notes (Table). “In the overall sample, participants reporting very short sleep had a 40% higher prevalence of moderate-to-severe CKD,” she says, “while those with obstructive sleep apnea (OSA) had a suggestive 20% higher prevalence.
Adequate Sleep May Help Reduce CKD Risk
For patients in the highest versus lowest SASHB quartile, the researchers observed a 36% significantly higher moderate-to-severe CKD prevalence; likewise, the prevalence was significantly higher among those with higher SASHB. “Participants with the most SASHB plus OSA had a 28% increased moderate-to-severe CKD prevalence,” Dr. Jackson says. This study, she notes, contributes to the identification of modifiable CKD risk factors, which “enhances our understanding of CKD etiology and may lead to novel approaches for preventing, delaying, or treating/managing renal disease.”
Dr. Jackson recommends that nephrologists, dialysis nurses, and others who work with patients with CKD assess and help to improve patients’ sleep habits, both in terms of duration and in quality, as doing so may help reduce the risk of CKD. “The American Academy of Sleep Medicine recommends that patients consistently achieve at least 7 hours of sleep on a daily basis,” she says. Finally, she points out that obesity can contribute to apnea/hypoxic burden and is a driver of health consequences, including CKD, which underscores the importance of reducing its burden.
In regard to future research on the association between sleep disorders and CKD, Dr. Jackson would like to see these findings replicated in a study with larger sample sizes and a broader age range (including younger patients). “Future studies should also employ kidney function equations that remove the race modifier from equations that estimate kidney function,” she says. “Doing so could help reduce potential harms caused by suboptimal prevention efforts as well as delayed diagnoses and specialty care among Black individuals.”
Multiple, Objectively Measured Sleep Dimensions Including Hypoxic Burden and Chronic Kidney Disease: Findings from the Multi-Ethnic Study of Atherosclerosis https://thorax.bmj.com/content/early/2020/12/04/thoraxjnl-2020-214713