Kinetic estimated glomerular filtration rate and drug dosing in critically ill patients with acute kidney injury-A prospective observational study

Objective To study the impact of kinetic glomerular filtration rate (kGFR) on clinical decision making and its implications on drug dosing compared to that of estimated GFR (eGFR) using chronic kidney disease epidemiology collaboration (CKD-EPI) equation in critically ill patients with acute kidney injury (AKI) admitted in a tertiary level intensive care unit (ICU).Methods Cross-sectional, prospective, observational study design. All patients admitted to Medical ICU, Fortis Hospital, Bangalore with AKI defined as per AKI network (AKIN) criteria. Patients were recruited after approval from the scientific and institutional ethics committee, with written informed consent. Serum creatinine values at admission and further values were noted. GFR was calculated using both formulas (CKD-EPI and kGFR) and documented at all intervals of creatinine sampling. Drugs requiring renal dose modification along with the dosing were documented. Sample size was calculated after a pilot study and a total of 107 patients were analyzed.Results Incidence of AKI was 12.84%. The mean (+/- SD) eGFR was 37.25 (+/- 29.4) and kGFR was 42.5 (+/- 33.2), (p-value .003). 70 (65.42%) patients required drug dose change when kGFR was used. Dosing changes from Day 1 to Day 5 are 53/104 (50.9%), 39/81 (48.1%), 12/26 (46.1%), 2/9 (28.5%), 1/2 (50%). Predominant dose changes were for antimicrobials: vancomycin (35.7%), acyclovir (23.1%), and meropenem (23%).Discussion Drug dosing using different methods of GFR calculation showed a difference in the dosing in 65.42% of patients with AKI. Accounting for change in creatinine over time using kinetic GFR may lead to better drug dosing in critically ill patients with AKI.Conclusion Our study shows that calculating GFR using kGFR formula instead of CKD-EPI may change drug dosages among patients with AKI admitted in ICU. By replacing conventional GFR estimation formulas with kGFR we may reduce the drug dosing inaccuracies that are currently prevalent in this cohort of patients.