Author(s): Lee JP, Dang AT
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Abstract STUDY DESIGN: A retrospective chart review. OBJECTIVES: To evaluate different methods of estimating renal function compared with patient-specific vancomycin and aminoglycoside (AG) clearance (CL(DRUG)) in patients with spinal cord injury (SCI), and to develop a new equation to more accurately estimate glomerular filtration rate (GFR) in SCI patients in order to optimize dosing for vancomycin and AG. SETTING: Veterans Affairs medical center in California, United States of America, tertiary care facility with the largest inpatient SCI center in the VA system. METHODS: Retrospective data collection from patient records. Pharmacokinetic analysis was performed to obtain actual CL(DRUG,) which is compared with different methods of estimating GFR.A total of 310 patients were initially assessed; however, only 141 patients met the inclusion criteria, had a diagnosis of chronic SCI, and received vancomycin or AG with at least one drug level at steady state from January to December of 2008. RESULTS: All four equations evaluated to estimate GFR significantly overestimated CL(DRUG): the Modification of Diet in Renal Disease equation by 141\%, Cockcroft-Gault equation by 83\%, Chronic Kidney Disease Epidemiology Collaboration equation by 82\% and 24-h endogenous creatinine clearance by 71\% (P<0.001). The modified Cockcroft-Gault equation (CL(M)) showed improvement, however, still overestimated CL(DRUG) by 39\% (P<0.001). Thus, a new equation for SCI (CL(SCI)) was developed which underestimated CL(DRUG) by <5\% (P=0.16). CONCLUSION: Compared with different methods of estimating GFR, CL(SCI)=2.3 × x (0.7) (x equals CL(M) in ml min(-1)) more accurately estimates CL(DRUG) in chronic SCI patients.
This article was published in Spinal Cord
and referenced in Journal of Drug Metabolism & Toxicology