Colistin and polymyxin B for treatment of nosocomial infections in intensive care unit patients: pharmacoeconomic analysis

Background The emergence and rapid spread of multidrug-resistant gram-negative bacteria related to nosocomial infections is a growing worldwide problem, and polymyxins have become important due to the lack of new antibiotics. Objectives To evaluate the outcomes and pharmacoeconomic impact of using colistin and polymyxin B to treat nosocomial infections. Setting Neurosurgical, cardiovascular, or transplantation intensive care unit (ICU) at the Clinical Hospital of the University of Campinas (São Paulo, Brazil). Method A retrospective cohort study was conduct in patients in the ICU. The renal function was determined daily during treatment by measuring the serum creatinine. A cost minimization analysis was performed to compare the relative costs of treatment with colistin and polymyxin B. Main outcomes measure The outcomes were 30-day mortality and frequency and onset of nephrotoxicity after beginning treatment. Results Fifty-one patients treated with colistin and 51 with polymyxin B were included. 30-day mortality was observed in 25.49% and 33.33% of patients treated with colistin and polymyxin B, respectively; Nephrotoxicity was observed in 43.14% and 54.90% of patients in colistin and polymyxin B groups, respectively; and onset time of nephrotoxicity was 9.86 ± 13.22 days for colistin and 10.68 ± 9.93 days for polymyxin B group. Colistin treatment had a lower cost per patient compared to the cost for polymyxin B treatment (USD $13,389.37 vs. USD $13,639.16, respectively). Conclusion We found no difference between 30-day mortality and nephrotoxicity between groups; however, colistin proved to be the best option from a pharmacoeconomic point of view.