Abstract: TH-PO744

Absolute versus Percentage Renal Functional Losses in Patients with Diabetes and CKD

Session Information

Category: Diabetes

  • 502 Diabetes Mellitus and Obesity: Clinical

Authors

  • Martin, William P., National University of Ireland, Galway, Ireland
  • Griffin, Tomas P., National University of Ireland, Galway, Ireland
  • Lappin, David W., Saolta University Health Care Group, Galway, Ireland
  • Griffin, Damian Gerard, Saolta University Health Care Group, Galway, Ireland
  • Ferguson, John P., HRB Clinical Research Facility, Galway, Ireland
  • O'Brien, Timothy, National University of Ireland, Galway, Ireland
  • Griffin, Matthew D., National University of Ireland, Galway, Ireland
Background

Chronic kidney disease (CKD) management focuses on minimizing the rate of renal functional loss, usually expressed in absolute terms of mL/min/BSA lost per annum. We evaluated the impact of expressing renal functional loss as a percentage of existing renal function on the interpretation of renal functional trends of patients with diabetes before and after attending a Diabetes Renal Clinic (DRC).

Methods

All patients attending a DRC at a tertiary referral center from 2008 to 2012 were reviewed. Serial laboratory indices were recorded from 2004 to 2014. Linear mixed effects models fitted using the R-package ImerTest were used to calculate absolute eGFR slopes. In a second analysis, similar mixed effects models were fitted with log-transformed eGFR as the response, to estimate annual percentage decline in eGFR. Renal function was estimated using both MDRD and CKD-EPI equations.

Results

147 subjects with ≥3 available eGFR values for ≥1 year before and after first DRC attendance were categorized based on presumptive CKD etiology. Rates of renal functional loss were calculated with similar results being obtained using both MDRD and CKD-EPI estimating equations (Table).

Conclusion

Following DRC consultation, absolute rate of eGFR decline was similar for T1D but slower for T2D and additional CKD etiology groups. Expressed as a percentage of prior eGFR, renal function declined more rapidly in T1D, similarly in T2D, and more slowly in those with additional CKD etiologies. Thus, interpretation of the impact of a CKD intervention is influenced by the initial eGFR and by the approach used to calculate renal functional decline.

Baseline characteristics at first DRC attendance and renal functional losses before and after first DRC attendance stratified by CKD etiology (n = 147).
 Type 1 Diabetes (T1D) (n = 32)Type 2 Diabetes (T2D) (n = 91)Diabetes with Additional CKD Etiology (n = 24)
Age [mean ± SD; years]43.8 ± 16.269.1 ± 10.069.5 ± 10.5
Male [n (%)]19 (59.4)60 (65.9)17 (70.8)
Diabetes duration [median (IQR); years]21.0 (16.7)10.1 (11.7)9.3 (4.8)
CKD-EPI eGFR [mean ± SD; mL/min/BSA]59.4 ± 30.844.5 ± 17.840.3 ± 14.7
MDRD eGFR [mean ± SD; mL/min/BSA]56.5 ± 29.545.0 ± 17.540.9 ± 14.5
Urine ACR [median (IQR); mg/g]508.9 (1900.0)176.1 (779.1)38.1 (512.4)
 Type 1 Diabetes (T1D) (n = 32)Type 2 Diabetes (T2D) (n = 91)Diabetes with Additional CKD Etiology (n = 24)
Absolute loss of renal function (mL/min/BSA/year)Before DRCAfter DRCpBefore DRCAfter DRCpBefore DRCAfter DRCp
CKD-EPI eGFR-3.78-4.58.430-4.04-2.34.005-4.19-0.73.003
MDRD eGFR-3.14-4.66.133-3.82-2.50.035-3.87-0.87.008
Percentage loss of renal function (%/year)Before DRCAfter DRCpBefore DRCAfter DRCpBefore DRCAfter DRCp
CKD-EPI eGFR5.20%14.49%.0028.01%7.49%.7708.82%2.12%.057
MDRD eGFR4.80%14.51%.0017.57%7.54%.9868.16%2.30%.084

Funding

  • Government Support - Non-U.S.