How different urinary albumin excretion rates can predict progression to nephropathy and the effect of treatment in hypertensive diabetics.
OBJECTIVE
The efficacy of a treatment in a clinical trial depends in part on where the cut-off point is placed for the test result used to select patients for the trial, and this applies to irbesartan in the Irbesartan Microalbuminuria II (IRMA II) trial for preventing nephropathy.


METHODS
Patients in the IRMA II trial were stratified into different pre-treatment albumin excretion rate (AER) ranges to compare the proportion of patients starting in these different ranges (i) that progressed to develop nephropathy within 24 months and (ii) whose AER was over 40 microg/minute at three months.


RESULTS
The proportion of patients with pre-treatment AER values between 20 and 40 microg/minute progressing to develop nephropathy was 1.25% in the placebo group and 0.78% in the irbesartan group, while for pre-treatment AER values between 41 and 200 microg/minute, 24.4% and 11.2% develop nephropathy respectively in the placebo and irbesartan groups. In patients with a pre-treatment AER of 20 to 30 microg/minute, 32.5% and 13.6% respectively in the placebo and irbesartan groups had a value exceeding 40 microg/minute at three months.


CONCLUSIONS
The data demonstrate that irbesartan is effective in reducing the onset of nephropathy within two years when the pre-treatment AER is above 40 microg/minute, but if the AER is below this level it progresses unusually to nephropathy within two years. Irbesartan also slows progression of AER to over 40 microg/minute for patients with pre-treatment AER values at or above 20 microg/minute and these patients should be treated.
Llewelyn
D E Huw
DE
Department of Medicine, Luton and Dunstable Hospital, Luton, Bedfordshire LU1 4OZ, UK. HuwLlewelyn@I&d-anglox-nhs.org.uk
Garcia-Puig
Juan
J
D000328:Adult; D000368:Aged; D000419:Albuminuria; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001713:Biphenyl Compounds / Q000627:therapeutic use*; D003925:Diabetic Angiopathies / Q000150:complications / Q000188:drug therapy* / Q000652:urine*; D003928:Diabetic Nephropathies / Q000209:etiology*; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy* / Q000652:urine*; D000077405:Irbesartan; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013777:Tetrazoles / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D001713:Biphenyl Compounds; D013777:Tetrazoles; D000077405:Irbesartan