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

Response to Kaiser, Florack, and Sawicki

We thank Kaiser, Florack, and Sawicki (1) for their interest in our article (2). The glomerular filtration rate (GFR) values in Fig. 2 represent the mean values of measurements carried out at the specified visits. However, the rates of decline in GFR cannot be correctly estimated from Fig. 2, but are instead calculated from paired observations of changes in GFR and specified in the results section. GFR values at baseline were available from 42, 38, and 39 patients from the placebo, irbesartan 150-mg, and irbesartan 300-mg groups, respectively, whereas paired observations of changes in GFR during the initial 3 months of the study were accessible from 37, 37, and 34 patients in the placebo, irbesartan 150-mg, and irbesartan 300-mg groups, respectively. Rates of decline in GFR during the initial 3-month period were 1.3 ± 0.7, 1.2 ± 0.7, and 1.0 ± 0.8 ml · min⁻¹ · month⁻¹, as specified in the results section.

According to Fig. 2, GFR was unchanged from baseline to the end of the study after withdrawal of antihypertensive medication (24 + 1 month) in the placebo group compared with a decline in GFR of 10 ml/min in the irbesartan 150-mg group and 5 ml/min in the irbesartan 300-mg group. However, changes in GFR from baseline to the end of the study cannot be precisely evaluated from Fig. 2 due to fewer patients at the end of the study. By paired comparisons of changes in GFR from baseline to the end of the study after withdrawal of antihypertensive medication (24 + 1 month), rates of decline in GFR were 0.3 ± 0.1, 0.5 ± 0.1, and 0.3 ± 0.1 ml · min⁻¹ · month⁻¹ in the placebo (23 patients), irbesartan 150-mg (17 patients), and irbesartan 300-mg (19 patients) groups, respectively (P = NS).

In conclusion, rates of decline in GFR during the study were similar in the placebo and irbesartan-treated groups, as specified in the results section of our article (2).