Interview with
Jeffrey H. Burbank
Founder& CEO of NxStage

Hemodialysis.com: What are the main findings of the study?

We found that African Americans, women, and those with diagnosed hypertension, diabetes, cardiovascular disease, peripheral artery disease, chronic lung disease, hepatitis C, dementia, acute kidney injury, and those with a greater number of hospitalizations had greater variability in eGFR.

We also found that after a median follow-up of 4.9 years, there were 23.66%, 25.68%, and 31.23% deaths among patients in the lowest, intermediate, and highest tertiles of eGFR variability, respectively.

Compared with those in the lowest tertile of eGFR variability, patients in the highest tertile had 34% increased risk of death.

Hemodialysis.com: Were any of the findings unexpected?

Not at all.

It was our hypothesis that greater variability is likely a reflection of diminished renal functional reserve or a reflection of the overall burden of disease and therefore increased variability may be associated with increased risk of death. 

Hemodialysis.com: What should clinicians and patients take away from your report? 

First that longitudinal assessment of kidney function is important in understanding risk and future prognosis.

CKD is a dynamic disease, and kidney function fluctuates over time, and these fluctuations (or what we are terming eGFR variability) may be important in understanding risk.

A sudden rise in serum creatinine (or loss of eGFR) often triggers interventions directed at the suspected underlying cause (e.g., discontinuation of a diuretic or ACE inhibitor).

A subsequent return in serum creatinine to the patient’s prior baseline usually provides reassurance that the intervention was appropriate. 

Our findings suggest that patients in whom such fluctuations are more common are nevertheless at increased risk for death, despite a return of serum creatinine to baseline. 

Hemodialysis.com : What recommendations do you have for future research as a result of this study?  

There are many questions that should be asked.

Primarily, we are interested in whether eGFR variability is also associated with increased risk of ESRD.

Other questions could be whether incorporating eGFR slope and eGFR variability in the CKD classifications system improves the classification system itself. It is also important to further explore the fascinating nexus of acute kidney injury and chronic kidney disease.

It also should be noted that similar to the automation of eGFR reporting in electronic health records, longitudinal measures such as eGFR slope and eGFR variability should also be offered as menu options

Reference:

Greater variability in kidney function is associated with an increased risk of death

Ziyad Al-Aly, Sumitra Balasubramanian, Jay R McDonald, Jeffrey F Scherrer
and Ann M O'Hare
Kidney Int advance online publication,
August 1, 2012; doi:10.1038/ki.2012.276