Observed link between sleep apnea and CKD risk may be due to obesity
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Although study results showed severe obstructive sleep apnea was associated with increased risk for incident chronic kidney disease, the risk was attenuated and no longer statistically significant after adjusting for obesity.
This finding led Kelsie M. Full, PhD, MPH, of the University of Minnesota, and colleagues to suggest that sleep apnea may not be an independent risk factor for the development of CKD; rather, they contended, the link may be due to higher BMI, a risk factor that is common in patients who have either condition.
“To date, the research investigating the association of [obstructive sleep apnea] OSA and poor sleep characteristics with incident CKD has focused primarily on individual dimensions of sleep and has relied upon either previous clinical diagnoses of OSA or self-reported measures of sleep,” the researchers wrote. “It has been estimated that up to 80% of individuals who meet the diagnostic criteria for OSA remain undiagnosed.”
According to Full and colleagues, this – coupled with the fact that patients with obstructive sleep apnea are at increased risk for established CKD risk factors including obesity, hypertension, type 2 diabetes, oxidative stress and inflammation – indicates further investigation is required.
“Although epidemiologic and pathophysiologic evidence suggests an association between OSA and risk of incident CKD, understanding of the association remains incomplete,” they argued.
To elucidate on the area, 1,525 patients in the Atherosclerosis Risk in Communities study were assessed, with researchers categorizing obstructive sleep apnea severity by events per hour (normal, less than five; mild, five to 14.9; moderate, 15 to 29.9; and severe, at least 30) and determining risk for incident CKD stage 3 or higher.
Patients were followed for a median of 19 years. During this time, 461 CKD events occurred.
Researchers found that, after adjusting for demographics and lifestyle behaviors, severe obstructive sleep apnea was associated with a 51% increased risk for CKD compared with no obstructive sleep apnea (hazard ratio [HR] = 1.51). However, this risk was reduced to an HR of 1.07 after adjusting for BMI, making it no longer statistically significant.
“Disentangling the relations between obesity, OSA, and CKD is challenging given that obesity is upstream from both conditions,” the researchers wrote.
Still, Full and colleagues emphasized the need for continued research into sleep apnea, especially given the frequency with which it goes undiagnosed.
“Although [obstructive sleep apnea] does not seem to be an independent risk factor for CKD, it associated with both poor quality of life and cardiometabolic risk, including increased risk of CKD risk factors,” they concluded. “As such, improving the diagnosis and treatment of OSA remains a public health priority.”
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