Angiotensin-converting enzyme inhibitors versus angiotensin receptor blockers for diabetic nephropathy: a retrospective comparison.

INTRODUCTION: There are no adequate head-to-head comparisons of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB) in type 2 diabetic patients in spite of some interesting attempts. Furthermore, there are no adequate studies about the effects of ACE inhibitors in type 2 diabetic patients, who are the great majority of diabetic individuals. This study has retrospectively compared the effects of ACE inhibitors and ARBs used to treat diabetic nephropathy in a group of type 2 diabetic subjects.

DESIGN AND METHODS: Patients (n=154) were treated with ACE inhibitors (mean age 59.5+/-13.3 years, 52.6% were male). Eighty-five patients had been treated with ARBs from 1999 until now (mean age 62.6+/-10.9 years, 56.0% were male, differences not significant). Kaplan-Meier survival analysis was used to calculate survival before reaching end-stage renal disease (ESRD) (glomerular filtration < 15 ml/min, stage V of renal disease as defined by KDOQI clinical guidelines) or starting renal replacement therapy. Only patients treated for more than six months were included in the survival analysis. Comparison of survival was made at three, five and seven years after starting treatment.

RESULTS: Pre-ESRD survival was 91.9% at three years, 81.6% at five years and 61.9% at seven years of follow-up for patients treated with ACE inhibitors. For patients treated with ARBs, pre-ESRD survival was 95.3% at three years, 82.1% at five years and 78.2% at seven years of follow-up (p=0.02, log-rank test). At 36 months, the comparative odds ratio for having started renal replacement therapy or reaching end-stage renal failure was 0.246 (95% confidence interval 0.114-0.531, p<0.001 for chi-square and likelihood ratio tests). The risk for the ARB cohort was 0.682 (95% confidence interval 0.578-0.804), meanwhile for ACE inhibitor patients it was 2.768 (95% confidence interval 1.481-5.172).

CONCLUSIONS: The effects of ACE inhibitors and ARBs seem to be different, favouring the use of ARBs. These results may have been influenced by the different circumstances when each kind of drug was indicated, since ARBs were used with the specific recommendations for control of blood pressure in diabetic patients. An earlier referral of these patients may also have had some effect on these results. The need for a well-designed prospective study on type 2 diabetic patients with heavy proteinuria is warranted.