Last Updated: 2009-03-19 8:00:36 -0400 (Reuters Health)

Patients with early chronic kidney disease are at increased risk of sleep apnea, clinicians from California report in the March issue of the journal Chest.

"We believe the findings of our study fill an important gap in clinical observation," lead author Dr. John J. Sim from Kaiser Permanente Los Angeles Medical Center told Reuters Health. "Our results show that the risk of sleep apnea is 20% to 40% higher in patients with early chronic kidney disease. In advanced chronic kidney disease such as the dialysis population, the greater rate of sleep apnea has been well described."

To determine whether an association exists between sleep apnea and chronic kidney disease before end-stage renal disease occurs, Dr. Sim and colleagues analyzed a group of patients with a range of kidney function from normal- to late-stage chronic kidney disease. Subjects included roughly 1.1 million adult Kaiser Permanente members who had undergone one or more serum creatinine tests during the 3-year observation period.

"What we have described from a large ethnically diverse population database of over 1 million members is that even in early chronic kidney disease, sleep apnea prevalence is higher than in those without kidney disease," Dr. Sim told Reuters Health.

Overall, 2.5% of the study population had sleep apnea and, according to the researchers, the risk of sleep apnea was greater in patients with decreased kidney function, including those with clear chronic kidney disease, defined by an estimated glomerular filtration rate (eGFR) of less than 60 mL/min per 1.73 m², when compared to patients with normal kidney function.

The odds ratios for sleep apnea by eGFRs of 75 to 89, 60 to 74, 45 to 59, 30 to 44, and 15 to 29 mL/min per 1.73 m² were 1.22, 1.32, 1.42, 1.37, and 1.32, respectively, compared to normal kidney function.

"The increased odds ratios for eGFRs greater than 45 mL/min per 1.73 m² were sustained even after controlling for diabetes, heart failure, and hypertension," Dr. Sim and colleagues report.

"Given the fact that sleep apnea leads to some very important clinical sequelae, such as cerebrovascular disease, cardiovascular disease, and hypertension, among others, we wonder whether chronic kidney disease may be another manifestation of sleep apnea," Dr. Sim said.

"I believe that our study asks an important clinical question of whether managing sleep apnea effectively early can stabilize and prevent progression of kidney disease," he added.

Chest 2009;135:710-716.