Kidney Function During and After Withdrawal of Long-Term Irbesartan Treatment in Patients With Type 2 Diabetes and Microalbuminuria

Response to Andersen, Bröchner-Mortensen, and Parving

We read with great interest the article by Andersen, Bröchner-Mortensen, and Parving (1) about the effects of long-term treatment with irbesartan on kidney function in a subgroup of the Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria Study (IRMA)-2 trial (2). In this population, the authors did not find a significant difference between irbesartan and placebo administration with respect to the change in the glomerular filtration rate (GFR). In the results section of the article, the authors report that a similar change in the GFR occurred in all study groups during the first 3 months (loss of GFR: 1.0 to 1.3 ml · min⁻¹ · 1.73 m⁻² · month⁻¹) as well as for the rest of the follow-up period (0.3 to 0.4 ml · min⁻¹ · 1.73 m⁻² · month⁻¹). However, in Fig. 2, the slope of GFR for placebo is exactly the same during the entire duration of the study, including the first 3 months, 0.3 ml · min⁻¹ · 1.73 m⁻² · month⁻¹, which is obviously contradictory to the aforementioned numbers in the results section of the article (1). Therefore, the loss of GFR may be more pronounced in patients treated with irbesartan than in those treated with placebo. In fact, when GFR values at the beginning of the study are compared with the final values at the end of the withdrawal period after 25 months (Fig. 2), there seems to be no loss of GFR in the placebo group at all, whereas GFR declined by about 10 and 6 ml/min in the 150- and 300-mg irbesartan groups, respectively.