Effects of short-term addition of NSAID to diuretics and/or RAAS-inhibitors on blood pressure and renal function

BACKGROUND: The combined post-operative use of diuretics and/or renin-angiotensin-aldosterone system (RAAS) inhibitors may increase the risk of nonsteroidal anti-inflammatory drug (NSAID) associated renal failure because of a drug-drug interaction.

OBJECTIVE: The aim of this study was to investigate the effect of the short-term (<4 days) post-operative combined use of NSAIDs with diuretics and/or RAAS inhibitors on renal function and blood pressure.

SETTING: One teaching hospital in the Netherlands.

METHOD: The study-design was a prospective, observational cohort-study. Based on postoperative treatment with NSAIDs, the intervention-group was compared to a control-group (no NSAIDs treatment).

MAIN OUTCOME MEASURE: Systolic blood pressure and renal function expressed by the estimated glomular filtration rate (eGFR) calculated with the modification of renal desease formula.

RESULTS: 97 patients were included in the intervention-group, 53 patients in the control-group. Patient characteristics were comparable except for one variable: 'combined use of a diuretic with a RAAS inhibitor' which was higher in the control-group (62 vs. 43 %, p = 0.046). Odds ratio for clinically relevant increase in systolic blood pressure was 0.66 (CI95 % 0.3-1.5). Odds ratio for clinical relevant decrease in renal function was 2.44 (CI95 % 1.1-5.2). On day 4 eGFR of 3 patients in the intervention- and 1 in the control-group was <50 ml/min/1.73 m(2).

CONCLUSION: Odds ratios showed no significant difference of a clinically relevant increase in systolic blood pressure but showed a higher risk for a clinically relevant decrease in renal function in the intervention group. However this decrease resulted in a relevant impaired renal function (<50 ml/min/1.73 m(2)) in only 3 patients in the interventiongroup and 1 patient in the control-group. In the post-operative patient, without preexisting impaired renal function, concurrent diuretics and/or renin-angiotensinaldosterone system inhibitor therapy can be combined with short-term NSAID treatment.