Background Patients with kidney failure are one of the population’s subgroups who benefit most from antibiotic dosage optimisation. During 2014, the nephrology department and antimicrobial stewardship team agreed to adequate antibiotic dosage according to the estimated glomerular filtration rate (eGFR) of antibiotics with restricted conditions.

Purpose

1. To assess whether the initial dosage of antibiotics with restricted conditions was prescribed taking into account the recommendations based on eGFR.

2. To analyse if the dosage would have been different depending on the method used to calculate eGFR.

Material and methods Retrospective observational study in adult patients treated with restricted condition antibiotics during June 2015. Patients were selected from an electronic prescription programme and those who did not have laboratory data at baseline were excluded. Data collected were: demographic (age); analytic (serum creatinine, eGFR calculated by MDRD-4 and CKD-EPI at baseline); initial antibiotic dose and frequency. eGFR values were obtained from laboratory reports or calculated using the MDRD-4/CKD-EPI equation if they were not available. Percentage of agreement between initial prescribed doses, theoretical doses needed depending on the eGFR equation used and the agreed recommendations were calculated.

Results 180 treatments from 158 patients were included. Mean ± SD patient’s age was 58.26 ± 16.33 years. Patients’ kidney disease stage were: 45.6% grade 1, 23.4% grade 2, 10.8% grade 3a, 8.9% grade 3b, 8.2% grade 4 and 3.1% grade 5. Only 2.2% of prescriptions were for outpatients.

The percentage of restricted condition antibiotics prescribed were piperacillin-tazobactam (43.9%), meropenem (17.7%), cefepime (13.8%), imipenem-cilastatin (10%), ertapenem (6.11%), daptomycin (5.5%) and tigecycline (2.77%).

There was 86% agreement between the initial prescribed regimen and the recommended one according to patient eGFR. In 98% of treatments there were no differences between theoretical doses needed if eGFR was calculated using the MDRD-4 or CKD-EPI equations.

Conclusion Most antibiotics with restricted conditions were prescribed according to renal function recommendations. There were no differences between dosage regimens of restricted condition antibiotics depending on the equation used to calculate eGFR (MDRD or CKD-EPI) in our patients. This could be because a relevant number of patients had grade 1–2 renal failure and no dosage adjustment was required.

No conflict of interest.