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Earlier Nephrology Interventions Don’t Result in Lower Mortality Rates

Aug 12, 2011

Patients approaching end-stage renal disease are increasingly receiving the nephrology consultation they need before initiating kidney dialysis; however, the trend has surprisingly not resulted in an improvement in mortality rates, according to a new study.

The study of 323,977 older patients initiating kidney dialysis between 1996 and 2006 showed that the proportion of patients who first consulted with a nephrologist at least a year before initiation of dialysis increased by 62.0%, from 30.0% in 1996 to 48.5% in 2006, and the percentage of patients who received nephrology consultation less than 3 months before the initiation decreased from 49.6% to 34.7%.

Patients meanwhile started dialysis with increasingly preserved kidney function, from a mean estimated glomerular filtration rate of 8 mL/min/1.73 m2 in 1996 to 12 mL/min/1.73 m2 in 2006.

The findings also showed lower levels of patient anemia in later years, which the authors attributed to the increased use of erythropoiesis-stimulating agents, and peritoneal dialysis was used less commonly as the starting modality.

One-year mortality rates were unchanged, however (annual change in mortality rate, +0.2%; 95% confidence interval, 0% to +0.4%). After adjustment for changes in demographic and comorbidity patterns, the estimated annual reduction in the 1-year mortality rate was 0.9% (95% confidence interval, 0.7% to 1.1%).

The changes were said to be explained only partly by trends toward earlier nephrology consultation, and the annual mortality reduction after accounting for the timing of nephrology care was attenuated to 0.4% (0.2% to 0.6%).

The importance of receiving timely nephrology referral has long been emphasized, and national guidelines dating back to 1994 advised referral to a nephrologist for women with a serum creatinine level of 1.5 mg/dL and men with a serum creatinine level of 2.0 mg/dL or higher.

The potential benefits of early referral include the identification of reversible cases of chronic kidney disease (CKD) and the ability to receive treatment to slow the progression of CKD, management of metabolic complications of advanced CKD, and the optimal preparation for the chosen dialysis modality or kidney transplantation, according to the study.

Delayed care has meanwhile been associated with such negative outcomes as reduced access to peritoneal dialysis and kidney transplantation, as well as a higher chance of dialysis initiation through a central venous catheter rather than an arteriovenous fistula or graft.

In light of the many possible benefits, the authors hypothesized that mortality rates would be lower if the rates of earlier consultation were higher, and they said they were surprised that their results show otherwise.

“Given the existing literature reporting associations among later nephrology care and poor outcomes for these patients, one would have expected that these significant shifts in practice during the past decade would have resulted in meaningful improvements in patient outcomes,” the study authors wrote.

“However, we found only small improvements in 1-year mortality rates. This observation is surprising and requires differentiated consideration,” they wrote.

The researchers speculated that several factors could explain the lack of improvement. Recent studies, for example, have raised questions of the efficacy of costly interventions commonly provided to patients with advanced CKD.

These interventions include more aggressive erythropoiesis-stimulating agent use, aggressive efforts to lower blood pressure, revascularization of atherosclerotic renovascular disease, secondary cardiovascular prevention using statins, and initiation of dialysis with more preserved kidney function.

In addition, the guidelines for the management of CKD-associated metabolic bone disease have not been thoroughly tested.

“In hindsight, it may be that many of the interventions touted as benefits of early referral were less efficacious than previously thought,” the study authors wrote. “It is even possible that nephrologists, unknowingly, contributed to worse outcomes in patients new to dialysis.”

Limitations of the study include that the authors did not have details on the severity of CKD or cormorbid diseases at the time of nephrology referral, and other outcomes that may have been affected by the timing of the nephrology referral, such as hospital rates or nutritional status, were also not assessed. In addition, there appears to be a recent trend of improved mortality rates overall among older patients starting dialysis.

In light of the findings, however, the researchers suggest that more needs to be done to make sure the various interventions targeted to older kidney disease patients are indeed worthwhile.

“The contrast between increasing adoption of practice guidelines that recommend early nephrology referral and the apparent lack of a meaningful improvement in survival raises the question of whether earlier is necessarily better.

“New approaches to improving care will need to be identified and tested to justify the additional expense, effort, and potential burden of nephrologist-driven health care interventions, including dialysis,” they wrote.

Arch Intern Med. Aug. 28, 2011;171:1371-1378.