Impact of irbesartan, blood pressure control, and proteinuria on renal outcomes in the Irbesartan Diabetic Nephropathy Trial.
BACKGROUND
It is important to know the reliability of early changes in proteinuria in predicting late renal outcomes. The IDNT was a trial in which treatment assignment, baseline and follow-up blood pressure determinations, and albumin/creatinine ratios (ACR), and renal outcomes were recorded.


METHODS
Risk of renal outcomes in the IDNT was assessed by proportional hazards modeling as a function of treatment assignment, and achieved systolic blood pressure (SBP) both without, and then with, inclusion of values for baseline proteinuria and early changes in proteinuria.


RESULTS
In models without ACR variables, both treatment with irbesartan and achieved SBP during follow-up were significantly predictive of the risk of renal outcomes. Addition of ACR variables to the models reduced the apparent impact of assignment to irbesartan by 52% to 81%, and irbesartan was no longer a significant predictor of renal outcomes. Conversely, addition of ACR variables to the models attenuated the effect of achieved follow-up SBP by only 32% to 46%, and follow-up BP remained a highly significant predictor of renal outcomes.


CONCLUSIONS
The ability of early changes in proteinuria to predict the impact of treatment on renal outcomes is a function of the specific treatment. One must use caution in using early changes in proteinuria as a surrogate for longer-term renal outcomes.
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa, USA. lawrence-hunsicker@uiowa.edu
Lawrence G
LG
Hunsicker
Robert C
RC
Atkins
Julia B
JB
Lewis
Gregory
G
Braden
Paul J Champion
PJ
de Crespigny
Giacomo
G
DeFerrari
Paul
P
Drury
Francesco
F
Locatelli
Thomas B
TB
Wiegmann
Edmund J
EJ
Lewis
D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001713:Biphenyl Compounds / Q000627:therapeutic use*; D001794:Blood Pressure; D003928:Diabetic Nephropathies / Q000188:drug therapy / Q000453:epidemiology; D006801:Humans; D000077405:Irbesartan; D011237:Predictive Value of Tests; D011507:Proteinuria / Q000188:drug therapy* / Q000453:epidemiology*; D012307:Risk Factors; D013777:Tetrazoles / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D001713:Biphenyl Compounds; D013777:Tetrazoles; D000077405:Irbesartan