SAN DIEGO – A healthy lifestyle cut the risk of cardiovascular events and death in chronic kidney disease, but it had no significant impact on the risk of renal events, preliminary results from an ongoing study have demonstrated.
"The impact of a healthy lifestyle has been studied most often in the general population, but lifestyle as a predictor of adverse outcomes has not been previously evaluated in individuals with CKD," Dr. Ana C. Ricardo said in an interview during a poster session at Kidney Week 2012.
Dr. Ana C. Ricardo
"There have been studies looking at individual risk factors such as smoking and chronic kidney disease progression alone, and exercise and mortality alone; but none have examined the impact of adherence to multiple lifestyle factors."
The findings come from 4 years of follow-up in 3,670 men and women with mild to moderate kidney disease who are enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study, a multicenter, nationwide study supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) to examine the epidemiology, management, and outcomes of CKD.
Dr. Ricardo, a nephrologist with the University of Illinois at Chicago, and her colleagues evaluated the association of a healthy lifestyle with clinical outcomes based on each participant’s healthy lifestyle score. This was calculated by allocating one point for each of the following factors measured at study entry: not currently smoking, engaged in moderate exercise (defined as 150 minutes or greater per week), engaged in vigorous exercise (defined as 75 minutes or greater per week), and having a urinary sodium output of less than 100 mEq/day.
Outcomes of interest were progression of CKD (defined as 50% or greater estimated glomerular filtration rate loss or end-stage renal disease), the development of cardiovascular events (defined as myocardial infarction, stroke, heart failure, or peripheral arterial disease), or death. The researchers used multivariable Cox proportional hazards regression models to determine the impact of the lifestyle factors on these outcomes.
Dr. Ricardo reported that 86% of participants adhered to one or two healthy lifestyle factors. Women, non-Hispanic whites, and college graduates were more likely to have a healthy lifestyle score of 3. Participants with a healthy lifestyle score of 1 had a 35% reduced risk of cardiovascular events or death. This risk was reduced further for those with a score of 2 or 3 (45% and 44%, respectively).
The researchers also found that patients with a healthy lifestyle score of 1 had a 30% reduced risk of CKD progression – but this risk reduction did not reach statistical significance, and risk was not reduced further among those with a score of 2 or 3 (24% and 7%, respectively). "We will explore this in further analyses," Dr. Ricardo said.
She acknowledged certain limitations of the study, including its observational design. "This is a work in progress," she said of the work. "We have more analysis to do. This is just the beginning."
Kidney Week 2012 was sponsored by the American Society of Nephrology. The CRIC study was funded by the NIDDK. Dr. Ricardo said that she had no relevant financial conflicts to disclose.