J Cardiovasc Pharmacol. 1999;33 Suppl 1:S16-20; discussion S41-3. Angiotensin-converting enzyme inhibitors and kidney protection: the AIPRI trial. Maschio G, Alberti D, Locatelli F, et al. A protective effect of angiotensin-converting enzyme (ACE) inhibitors has been shown in patients with diabetic nephropathy but has not been clearly established in nondiabetic renal disease. A multicenter European study was designed to determine whether the ACE inhibitor benazepril was safe and effective in protecting residual renal function in patients with various renal diseases and mild to moderate renal failure. The trial involved 583 patients from 49 centers in Italy, France, and Germany. The patients were randomized to receive benazepril or placebo plus other antihypertensive agents, the target being a diastolic blood pressure of less than 90 mm Hg. Thirty-one patients in the benazepril group and 57 patients in the placebo group reached the end point [the time elapsed from entry to (a) doubling of serum creatinine (SCr) concentrations and (b) start of renal replacement therapy; p < 0.001 at 3 years]. The associated reduction in the relative risk of reaching the end point was 53% in benazepril-treated patients, with actuarial renal survival probability significantly better at 3 years. The best survival of renal function was observed in patients with chronic glomerular diseases and proteinuria greater than 1.0 g/24 h. Benazepril is effective in slowing the rate of progression and improving the survival of renal function in patients with renal diseases of various origins. This protective effect is associated with a clinically relevant decrease in both blood pressure and proteinuria. Kidney Int Suppl. 1997 Dec;63:S63-6. Long-term progression of chronic renal insufficiency in the AIPRI Extension Study. Locatelli F, Carbarns IR, Maschio G, et al. The Angiotensin-converting-enzyme Inhibition on Progressive Renal Insufficiency (AIPRI) Study showed that the ACE inhibitor benazepril provides protection against loss of renal function in patients with chronic renal insufficiency (CRI) caused by various renal diseases. As a result of unexpectedly low mortality in the placebo group, there was a substantial imbalance in mortality during the course of this study (8 patients on benazepril vs. 1 on placebo). The aim of the extension study was to follow-up the patients from the AIPRI core study until autumn 1996, focusing on CRI progression and mortality. Data collection was post hoc. Patients were treated according to investigators" usual practices, without knowledge of the core study trial medication or (initially) the core trial results. A new primary efficacy parameter was defined as the time from the start of core study treatment to the occurrence of the first event in the combined composite end-point of dialysis, renal transplantation or death related to renal disease. Serial serum creatinine levels and all-cause mortality were also recorded. The median total follow-up for core + extension periods was 6.6 years. Many patients from both treatment groups (64% on benazepril and 61% on placebo) received ACE inhibitors during follow-up. In the intention-to-treat analysis of the core + extension data, only 79 of 300 patients from the benazepril group, compared to 102 of the 283 patients from the placebo group needed dialysis or renal transplantation, or died related to renal disease (P < 0.013, log-rank test). The mortality imbalance seen in the core trial was not evident with the longer follow-up (25 deaths in the benazepril and 23 in the placebo group, before dialysis). These data clearly demonstrate a long-term beneficial effect in patients randomized to take benazepril during the core study, but because treatment during the extension period was not randomized, the results of this intention-to-treat analysis need to be interpreted with care. N Engl J Med. 1996 Apr 11;334(15):939-45. Effect of the angiotensin-converting-enzyme inhibitor benazepril on the progression of chronic renal insufficiency. Maschio G, Alberti D, Janin G, et al. BACKGROUND. Drugs that inhibit angiotensin-converting enzyme slow the progression of renal insufficiency in patients with diabetic neuropathy. Whether these drugs have a similar action in patients with other renal diseases is not known. We conducted a study to determine the effect of the angiotensin-converting-enzyme inhibitor benazepril on the progression of renal insufficiency in patients with various underlying renal diseases. METHODS. In a three-year trial involving 583 patients with renal insufficiency caused by various disorders, 300 patients received benazepril and 283 received placebo. The underlying diseases included glomerulopathies (in 192 patients), interstitial nephritis (in 105), nephrosclerosis (in 97), polycystic kidney disease (in 64), diabetic nephropathy (in 21), and miscellaneous or unknown disorders (in 104). The severity of renal insufficiency was classified according to the base-line creatinine clearance: 227 patients had mild insufficiency (creatinine clearance, 46 TO 60 ml per minute), and 356 had moderate insufficiency (creatinine clearance, 30 to 45 ml per minute). The primary end point was a doubling of the base-line serum creatine concentration or the need for dialysis. RESULTS. At three years. 31 patients in the benazepril group and 57 in the placebo group had reached the primary end point (P<0.001). In the benazepril group, the reduction in the risk of reaching the end point was 53 percent overall (95 percent confidence interval, 27 to 70 percent), 71 percent (95 percent confidence interval, 21 to 90 percent) among the patients with mild renal insufficiency, and 46 percent (95 percent confidence interval, 12 to 67 percent) among those with moderate renal insufficiency. The reduction in risk was greatest among the male patients; those with glomerular diseases, diabetic nephropathy, or miscellaneous or unknown causes of renal disease; and those with base-line urinary protein excretion above 1 g per 24 hours. Benazepril was not effective in patients with polycystic disease. Diastolic pressure decreased by 3.5 to 5.0 mm Hg in the benazepril group and increased by 0.2 to 1.5 mm Hg in the placebo group. CONCLUSIONS. Benazepril provides protection against the progression of renal insufficiency in patients with various renal diseases.