Angiotensin-converting enzyme inhibitors and renal failure in diabetes

Abstract

To the Editor: Suissa et al.1.Suissa S. Hutchinson T. Brophy J.M. Kezouh A. ACE-inhibitor use and the long-term risk of renal failure in diabetes.Kidney Int. 2006; 69: 913-919Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar reported on the risk of renal failure in diabetics treated with angiotensin-converting enzyme (ACE) inhibitors. They used a nested case–control design and thus excluded over 1800 patients from the final analysis. It is not clear why the entire cohort could not have been analyzed to address the issue of mortality. ACE inhibitors are intentionally prescribed to reduce mortality2.Strippoli G.F.M. Craig M. Deeks J. et al.Effects of angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists on mortality and renal outcomes in diabetic nephropathy: systematic review.BMJ. 2004; 329: 828-839Crossref PubMed Scopus (309) Google Scholar and to prolong time to dialysis.3.Lewis E.J. Hunsicker L.G. Bain R.P. Rohde R.D. The effect of angiotensin-converting-enzyme inhibition on diabetic nephropathy. The Collaborative Study Group.N Engl J Med. 1993; 329: 1456-1462Crossref PubMed Scopus (4783) Google Scholar It would be informative for the readers if the authors presented data for these two outcomes both separately and combined (e.g. death, dialysis, or transplant) for those prescribed ACE inhibitors and those not, using the entire cohort of 6102 patients. Only with this information can the readers determine if their conclusions are valid. As the authors themselves state ‘ACE inhibitors prolong life, thus increasing the opportunity for end-stage renal disease incidence’.1.Suissa S. Hutchinson T. Brophy J.M. Kezouh A. ACE-inhibitor use and the long-term risk of renal failure in diabetes.Kidney Int. 2006; 69: 913-919Abstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar In addition, a stepped-care approach to hypertension was often used in the era of this study.4.Kuchel O.G. Mahon W.A. McKenzie J.K. Ogilvie R.I. Approach to drug therapy for hypertension.Can Med Assoc J. 1979; 120: 565-570PubMed Google Scholar As such, ACE inhibitors may have been prescribed to patients with difficult to control blood pressure. It would be useful to know if the database had any blood pressure values and if there were any differences between the groups, as the severity of hypertension is arguably the single most important factor for progression of diabetic nephropathy. In view of the above comments, the conclusion that ACE inhibitors may increase the risk of renal failure in diabetes may not be justified.