SAN DIEGO — The more advanced the stage of chronic kidney disease, the greater the risk of developing heart failure and the higher the subsequent risk of death, results from a large analysis of Medicare patients showed.
“Even a modest degree of chronic kidney disease is a very strong predictor of having cardiovascular morbidity and mortality,” Dr. Charles A. Herzog said in an interview during a poster session at the annual meeting of the American Society of Nephrology.
“Chronic kidney disease is something that primary care physicians can easily detect, because it's very easy to do a serum creatinine in an office setting,” he said.
Dr. Herzog, director of the Minneapolis-based cardiovascular special studies center of the United States Renal Data System Coordinating Center, and his associate, Shuling Li, identified 1,089,716 patients aged 66 years and older from the general Medicare database and followed them between Jan. 1, 2006, and Dec. 31, 2007.
Patients with heart failure and end-stage renal disease at baseline were excluded from the analysis.
The researchers used a Cox proportional hazard model to assess the risk of developing incident heart failure, adjusting for demographics, comorbidities, and stage of chronic kidney disease based on ICD-9 codes 585.1-585.5 and 585.9.
They used the Kaplan-Meier method to estimate the age-adjusted survival of patients after the development of incident congestive heart failure.
At baseline, 59% of the patients were female and 88% were white; 23% were aged 66-69, 25% were aged 70-74, 22% were aged 75-79, 16% were aged 80-84, and 14% were aged 85 or older.
The majority (95.8%) had no chronic kidney disease, 0.4% had stage I-II disease, 1.4% had stage III-IV disease, and the remainder (2.4%) had an unknown stage of disease.
Dr. Herzog reported that after the 1 year of follow-up, heart failure occurred in 5.3% of patients with no chronic kidney disease at baseline, 12.7% of those with stage I-II disease, 15% of those with stage III-IV disease, and 12.3% of those whose disease stage was unknown.
Independent predictors of heart failure were as follows: age 70-74 years (hazard ratio, 1.30), age 75-79 years (HR, 1.75), age 80-84 years (HR, 2.42), and age 85 years and older (HR, 3.82).
Other independent predictors included black race (HR, 1.21), stage I-II chronic kidney disease (HR, 1.45), stage III-IV disease (HR, 1.68), and unknown stage of chronic kidney disease (HR, 1.27).
The researchers also found that the presence of certain comorbid conditions predicted heart failure, including anemia (HR, 1.22), diabetes (HR, 1.57), atherosclerotic heart disease (HR, 1.67), and dysrhythmia (HR, 1.94).
Over the 1-year period, 83% of patients with no chronic kidney disease survived, compared with 77% of those with stage I-II disease, 75% of those with stage II-IV disease, and 67% of those whose disease stage was unknown.
Dr. Herzog acknowledged that the study's reliance on Medicare claims data is a limitation.
“There can be some inaccuracy in claims,” he said. “But the large size of the sample probably helps deal with some of the deficiencies in the accuracy of the coding.”
Disclosures: Dr. Herzog disclosed that he is a consultant for Amgen Inc. and is a scientific adviser for CorMedix Inc. He also is a member of the Roche Foundation for Anemia Research board of trustees.
'Even a modest degree of chronic kidney disease is a very strong predictor' of cardiovascular morbidity.
Source DR. HERZOG