Early Frequent Nephrology Care Reduces Cardiovascular Risk Factors Postdialysis

Compared with age-matched controls, patients with chronic kidney disease (CKD) face a 5- to 10-fold higher risk for cardiovascular disease, including coronary artery disease, stroke, and heart failure. Cardiovascular events are the leading cause of death in patients with CKD. Interventions aimed at controlling traditional risk factors for cardiovascular disease (hypertension, diabetes, and dyslipidemia) were not associated with improvement in cardiovascular outcomes in populations of CKD patients.

Patients with CKD have uremia-related nontraditional risk factors such as anemia, proteinuria, mineral and bone disorder, malnutrition, metabolic acidosis, uremia toxins, oxidative stress, and inflammation. Previous studies have shown that predialysis nephrology care can effectively control complications related to CKD and reduce hospitalizations and mortality among patients with end-stage renal disease on maintenance dialysis therapy.

There are few data on the effectiveness of reducing the risk of cardiovascular complications with improved control of the uremia-related nontraditional factors. Using the National Health Insurance Research Database (NHIRD) in Taiwan, Ju-Yeh Yang, MD, MS, and colleagues conducted an observational cohort study to test the hypothesis that early frequent predialysis nephrology care would provide improved control of nontraditional cardiovascular risk factors and lead to fewer postdialysis major adverse cardiac events. The researchers reported results of the study in the American Journal of Kidney Diseases [2017;70(2):164-172].

The primary outcome of interest was the occurrence of major adverse cardiac events within 1 year following initiation of dialysis therapy. Major adverse cardiac events included hospitalization with a primary discharge diagnosis of characteristic procedure codes of acute myocardial infarction, acute heart failure, ischemic stroke (cardiovascular accident), hemorrhagic stroke (intracranial hemorrhage), and sudden death.

The NHIRD database includes deidentified claims data of reimbursements of the Taiwan National Health Insurance program. The current study enrolled patients ≥20 years of age who initiated maintenance dialysis therapy for >3 months from 1999 to 2012 (n=77,174). Patients who had a major adverse cardiac event 2 years prior to initiation of dialysis therapy were excluded (n=15,012), as were patients who had a major adverse cardiac event within 3 months of initiation of dialysis therapy (n=1361).

Of the remaining 60,329 patients, 40.6% (n=24,477) received early (≥6 months predialysis) and frequent (minimum of one visit to a nephrologist every 3 months) nephrology care; 21.2% (n-12,763) received early and infrequent nephrology care; and 38.3% (n=23,089) received late nephrology care prior to dialysis initiation. The proportion of early frequent nephrology care increased from 28.0% in 1999 to 50.1% in 2010 (P<.001) as revealed in trend analysis.

In the late group, the age at dialysis initiation was slightly younger than in the other groups. Women received nephrology care earlier and more frequently than males; patients with more comorbid conditions visited nephrologists earlier but not frequently.

There was a tendency to initiation dialysis with peritoneal dialysis among those with early frequent nephrology care; there was also an association between early frequent nephrology care and better economic status. There was a positive association between the intensity of early nephrology care and the prescription of erythropoiesis-stimulating agents (73.4%, 34.1%, and 22.5% for early frequent, early infrequent, and late, respectively; P<.001) and vitamin D (13.3%, 6.4%, 3.7%, respectively, P<.001).

Crude 1-year incidence rates of major adverse cardiac events were 4.9% for patients receiving early frequent nephrology care, 5.3% for patients receiving early infrequent nephrology care, and 4.7% for patients receiving late care. Following adjustment for baseline characteristics and comorbid conditions, patients in the early frequent nephrologist care group had the most favorable major adverse cardiac event outcomes.

Overall, compared with late nephrology care, there was an association of early frequent predialysis nephrology care and an ~10% lower risk for 1-year composite major adverse cardiac events (hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.82-0.96) for the first major adverse cardiac event and a relative risk [RR] of 0.91 (95% CI, 0.84-0.98) for recurrent major adverse cardiac events.

Considered individually, there was an association between early frequent care and a ~30% lower risk for heart failure (HR, 0.69 for the first heart failure and RR, 0.72 for recurrent heart failures), ~20% lower risk for cardiovascular accident (HR, 0.79 for first accident and RR, 0.80 for recurrent accidents), ~25% lower risk for intracranial hemorrhage (HR, 0.72 for first hemorrhage and RR, 0.75 for recurrent hemorrhages), and ~27% lower risk for sudden death (HR, 0.73). There was also an association between early but infrequent predialysis nephrology care and a 35% lower risk for sudden death (HR, 0.65; 95% CI, 0.45-0.95).

Associations between predialysis nephrology care and the risk for major adverse cardiac events were not significantly modified by age, diabetes status, dialysis modality, or economic status.
Study limitations included the use of administrative data that precluded access to physical and biochemical information.

“In conclusion, patients undergoing dialysis are at high risk for major adverse cardiac events. The predialysis period is crucial for preventing major adverse cardiac events. We found that early and frequent predialysis nephrology care for 6 or more months was associated with improved 1-year postdialysis major adverse cardiac event outcomes. Hence, we suggest that clinicians consider early consultation with nephrologists while providing health care to patients with CKD.”

TAKEAWAY POITNS

Researchers tested the hypothesis that early frequent nephrology care in the 6 months prior to dialysis therapy initiation would provide improved control of nontraditional cardiovascular risk factors faced by patients with chronic kidney disease, reducing postdialysis major adverse cardiac events.

In a cohort of 60,329 patients, 40.6% (n=24,277) had early frequent nephrology care, 21.2% (n=12,763) had early infrequent nephrology care, and 38.3% (n=23,089) had
late care.

The early frequent care group had ~10% lower risk for a major adverse cardiac event in the first year following initiation of dialysis therapy compared with the late nephrology care group.