Effects of NSAIDs on the incidence of hospitalisations for renal dysfunction in users of ACE inhibitors

Introduction: Although relatively safe, both NSAIDs and ACE inhibitors can cause renal dysfunction in patients with compromised renal function. Case reports indicate that the combined use of ACE inhibitors and NSAIDs increases the risk of renal dysfunction. It is not known how often and when renal dysfunction occurs in patients using a combination of ACE inhibitors and NSAIDs. Objective: The objective of the study was to investigate the effects of NSAIDs on the incidence of hospitalisations due to renal dysfunction in patients treated with ACE inhibitors. Study Design: Case-control study nested within a cohort of users of ACE inhibitors. Participants: All participants had at least two consecutive prescriptions for an ACE inhibitor. One hundred and forty-four cases were admitted to hospital for renal insufficiency during use of ACE inhibitors. There were 1189 randomly sampled control patients who did not have any hospital admission for renal dysfunction during use of ACE inhibitors. Main Outcome Measures: The risk for hospitalisation for renal dysfunction associated with exposure to NSAIDs in patients receiving ACE inhibitors was expressed as odds ratios (OR). Results: Of 144 cases, a total of 32 (22.2%) received NSAIDs in the 90 days before hospital admission for renal dysfunction. Recent start (<90 days) of an NSAID was associated with an increased risk of admission for renal dysfunction (adjusted OR 2.2; 95% CI 1.1-1.5). The increased risk was most pronounced in patients aged >70 years (adjusted OR 2.7; 95% CI 1.0-7.2). For patients who started NSAIDs and were dispensed at least three prescriptions in the 90 days preceding hospitalisation an adjusted OR of 7.1 (95% CI 1.8-28.7) was observed. Conclusions: This study strongly suggests an increased risk for hospitalisation for renal insufficiency in patients receiving ACE inhibitors who start using NSAIDs. Elderly patients receiving several prescriptions for NSAIDs in a short period of time are particularly at risk. Renal function should be closely monitored in these patients.