Background: The RENAAL Study has confirmed the renoprotective effects of Losartan in type 2 diabetes. In this subgroup analysis from the RENAAL Study, we hypothesized that the intensive care received by patients in a clinical trial setting also reduced the rate of decline in renal function through optimization of all risk factors.
Methods: We compared the rate of deterioration in renal function, expressed as the regression coefficient of the monthly serum creatinine (SeCr) reciprocal (beta-1/Cr) in 55 Chinese type 2 diabetic patients before and after entry into the RENAAL Study.
Results: Of the 55 patients, 44 had at least three out-patient SeCr measurements both before (2.9+/-2.4 years) and after (3.3+/-0.8 years) entry into the study for evaluation. In the Losartan group (n = 24), the median beta-1/Cr fell from -11.4 x 10(-5) l micro mol(-1) month(-1) before entry into the trial to -4.7 x 10(-5) l micro mol(-1) month(-1) following entry (P = 0.001). The respective figures were -9.1 x 10(-5) and -5.0 x 10(-5) l micro mol(-1) month(-1) (P = 0.01) in the placebo group (n = 20). A decrease in beta-1/Cr was observed in 21 (87.5%) and 14 (70.0%) patients in the Losartan and placebo groups, respectively. Spot urinary albumin-to-creatinine ratio was reduced by 56% (P = 0.001) in the Losartan group but the change was not significant in the placebo group. At the end of the study, patients in both groups had lower blood pressure and better lipid control. The frequency of patient visits to doctors and nurses were doubled.
Conclusions: The rate of renal function decline was significantly reduced in the majority of patients allocated to either Losartan or placebo following entry into the RENAAL study. These results suggest that in patients with diabetic nephropathy, implementation of a structured care protocol in a clinical trial setting facilities intensive treatment of risk factors confering renoprotective effects in addition to those resulting from Losartan treatment.