ISTANBUL, Turkey — Patients with stage 5D kidney disease and heart failure who snore are at increased risk for death compared with those who don't snore, according to a new study.

"We wanted to understand whether snoring — sleep-disordered breathing — is in some way related to cardiovascular and all-cause mortality," Claudia Torino, PhD, lead researcher from the National Research Council in Reggio Calabria, Italy, told Medscape Medical News.

Snoring affects about 60% of patients with chronic kidney disease, Dr. Torino explained. But whether snoring influences heart failure mortality has not been explored. Because snoring has been attributed, in part, to reversible pharyngeal edema secondary to volume expansion in heart failure patients, this would be valuable information to have.

Dr. Torino presented the study results here at the European Renal Association-European Dialysis and Transplant Association 50th Congress.

The researchers studied 827 patients with chronic kidney disease in Italy. They used clinical symptoms and radiologic and echocardiograpic tests to assess heart failure at baseline.

Snoring symptoms were self-reported, with spouse confirmation when possible. Subjects were classified as nonsnorers (n = 325), moderate snorers (n = 308), or heavy snorers (n = 194). Median follow-up time was 28 months.

At baseline, 16% of the study participants had heart failure. Heart failure predicted all-cause and cardiovascular mortality on univariate (< .001) and multivariate (< .02) Cox regression analyses, but snoring did not.

However, snoring did reportedly modify the association between heart failure and all-cause and cardiovascular mortality. The mortality risk rose with increasing frequency of snoring, after adjustment for age, sex, smoking, diabetes, systolic blood pressure, antihypertensive treatment, cardiovascular comorbidities, dialysis vintage, and levels of C-reactive protein, phosphate, cholesterol, hemoglobin, and albumin.

Table: Mortality Risk in Patients With Kidney Disease and Heart Failure

Mortality by Snoring Classification Hazard Ratio 95% Confidence Interval P Value
All-cause (n = 233)      
   Nonsnorers 0.9 0.6–1.5  
   Moderate snorers 1.5 1.1–2.1 .01
   Heavy snorers 2.5 1.5–4.2 <.001
Cardiovascular (n = 127)      
   Nonsnorers 0.8 0.5–1.5  
   Moderate snorers 1.6 1.1–2.3 .009
   Heavy snorers 3.1 1.8–5.3 <.001

 

"This is very important because heart failure is a nonmodifiable factor, but snoring is modifiable," said Dr. Torino. Snoring can be treated with continuous positive airway pressure machines or drugs. "These approaches can be useful, and might prevent some of these outcomes."

These results are particularly useful because snoring is a risk factor that "can be easily modified," Christoph Wanner, MD, from the University Clinic Würzburg in Germany, echoed to Medscape Medical News.

However, "you will need a lab to do sleep apnea testing," added Dr. Wanner, who was not involved in the study.

The next step will be an intervention trial to see if the treatment of snoring reduces mortality, he noted.

Dr. Torino and Dr. Wanner have reported no relevant financial relationships.

European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) 50th Congress: Abstract MP575. Presented May 20, 2013.

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