Dosage adjustment in medical patients with renal impairment at Groote Schuur Hospital

Abstract

Background. Many drugs are eliminated by the kidneys and therefore may require dose adjustment in patients with renal impairment. The need for dose adjustment is frequently neglected by prescribers.
Methods. We reviewed folders of patients admitted to the Groote Schuur Hospital general medical wards between January and March 2008. Patients with renal impairment, defined as an estimated glomerular filtration rate (eGFR) ≤50 ml per minute per 1.73 m2, were identified. In-patient prescriptions were captured if they were written after clinical notes indicated impaired renal function, or ≥1 day after renal function tests were performed. We determined what proportion of these prescriptions required dose adjustment and whether drug doses were appropriately adjusted.
Results. We found renal impairment in 32% (97/301) of medical admissions. There were 615 prescription entries for the 97 patients with renal impairment. Dose adjustment was required in 19% (117/615) of prescription entries, and only 32% (37/117) of these prescription entries were correctly dose adjusted. Of 97 patients, 69 received one or more drugs that required dose adjustment (median 1, range 1 - 5). All drug doses were correctly adjusted in 12% (8/69) of patients. Importantly, in the majority of patients (59% (41/69)) no doses had been correctly adjusted.
Conclusion. Consistent with international studies, drug dose adjustment in patients with renal impairment in a South African hospital was frequently neglected. Strategies to alert clinicians of the need for dose adjustment in renal impairment should be considered, including automated eGFR reporting and computerised aids to guide drug dosing, that account for renal impairment.