Study design and patient population
The study was planned as a retrospective cohort study and included 170 adult patients (age ≥18 years) who were followed in the ICU and received COL intravenously for documented resistant gram-negative bacterial infections in Niğde Education and Research Hospital between January 1st, 2012, and December 31st, 2019. We investigated risk factors associated with COL nephrotoxicity in general population and geriatric patients.
Exclusion criteria were as follows: having received COL for <72 hours; age <18 years; pregnancy; and acute and chronic renal failure at the beginning of COL treatment. For patients who had received multiple courses of COL therapy, only the first COL treatment was included in the study analysis.
The pharmaceutical preparation of COL used by the patients was Colimycin® (Kocak Farma, Istanbul, Turkey). One vial contains colistimethate sodium equivalent to 150 mg of COL base activity. A loading dose of 5 mg/kg was administered to all patients regardless of creatinine clearance. For patients with creatinine clearance ≥70 mL/min, the total daily dose was calculated as 5 mg/kg/day and administered in 2 equal doses.