Nephrotoxic drug burden among 1001 critically ill patients: impact on acute kidney injury

Background Nephrotoxic drug prescription may contribute to acute kidney injury (AKI) occurrence and worsening among critically ill patients and thus to associated morbidity and mortality. The objectives of this study were to describe nephrotoxic drug prescription in a large intensive-care unit cohort and, through a case–control study nested in the prospective cohort, to evaluate the link of nephrotoxic prescription burden with AKI. Results Six hundred and seventeen patients (62%) received at least one nephrotoxic drug, among which 303 (30%) received two or more. AKI was observed in 609 patients (61%). A total of 351 patients were considered as cases developing or worsening AKI a given index day during the first week in the intensive-care unit. Three hundred and twenty-seven pairs of cases and controls (patients not developing or worsening AKI during the first week in the intensive-care unit, alive the case index day) matched on age, chronic kidney disease, and simplified acute physiology score 2 were analyzed. The nephrotoxic burden prior to the index day was measured in drug.days: each drug and each day of therapy increasing the burden by 1 drug.day. This represents a semi-quantitative evaluation of drug exposure, potentially easy to implement by clinicians. Nephrotoxic burden was significantly higher among cases than controls: odds ratio 1.20 and 95% confidence interval 1.04–1.38. Sensitivity analysis showed that this association between nephrotoxic drug prescription in the intensive-care unit and AKI was predominant among the patients with lower severity of disease (simplified acute physiology score 2 below 48). Conclusions The frequently observed prescription of nephrotoxic drugs to critically ill patients may be evaluated semi-quantitatively through computing drug.day nephrotoxic burden, an index significantly associated with subsequent AKI occurrence, and worsening among patients with lower severity of disease.