Getting another abstract (or two) ready for Renal Week 2009

We are racing the deadline for our ASN abstract. We have a great data set on geriatric patients in a structured CKD clinic. We need to define stable renal function. Our first try used the CKD stages. Our cohort is restricted to CKD 3b and 4. So stable was any patient who began and ended the study in the same CKD stage. This has been done in the literature, so there is some precedence but it doesn’t feel right to me.

Think about two participants in our study, both GFRs fall by 3 cc/min over three years, just about what the Baltimore Longitudinal Study on aging predicts. Patient A started with an eGFR of 31 mL and Patient B started with an eGFR of 33. These patients have the same clinical course and outcome but Patient A goes from 31 to 28 mL/min and hence from CKD Stage 3 to 4 while Patient B goes from an eGFR of 33 to 33 so his stage does not change.

I need a definition of stable renal function. You can help by filling this 5 question anonymous survey. We are looking

How would you define stable renal function:

Candidate A: Change in GFR less than 2 cc/min/yr (essentially 3x the average rate determined by the Baltimore Longitudinal Study on Aging).

Candidate B: Change of GFR of less than 20% from baseline to the end of the study

Candidate C: Change of less than 10 mL/min from the baseline visit

Note: baseline visit is the 1st contact with us with a GFR<45 mL/min(CKD stage 3b), we removed any patient who does not have a second eGFR < 45 at least 3 months before the initial measurement.