Long-term progression of chronic renal insufficiency in the AIPRI Extension Study. The Angiotensin-Converting-Enzyme Inhibition in Progressive Renal Insufficiency Study Group.

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.