title: Risk factors for acute kidney injury (AKI) in patients treated with polymyxin B and influence of AKI on mortality: a multicentre prospective cohort study.
abstract: OBJECTIVE
  The objectives of this study were to assess risk factors for acute kidney injury (AKI) in patients treated with polymyxin B, a last resort antibiotic against Gram-negative bacteria, with a focus on dose, and to determine the impact of AKI on mortality of these patients.
  
  
  METHODS
  A multicentre prospective cohort study was performed including patients ≥18 years treated with intravenous polymyxin B for ≥48 h. The primary outcome was AKI defined by RIFLE criteria. Secondary outcomes were 30 day mortality and failure stage of AKI. Multivariate analysis with a Cox regression model was performed. The probability of developing AKI was determined in a logistic regression model.
  
  
  RESULTS
  Four-hundred-and-ten patients were included. AKI occurred in 189 (46.1%) patients. Polymyxin B dose ≥150 mg/day was a risk factor for AKI: adjusted HR = 1.95, 95% CI = 1.31-2.89, P = 0.01. Higher weight and age were also independently associated with AKI. The probability of developing AKI significantly increased with doses between 150 and 199 mg/day, regardless of patient weight, with no significant increase with higher doses. Higher weight also increased the risk in patients receiving the same daily doses. AKI was barely associated with increased risk for 30 day mortality (adjusted HR = 1.35, 95% CI = 0.99-1.85, P = 0.06), while ≥150 mg/day did not increase this risk despite its association with AKI.
  
  
  CONCLUSIONS
  Polymyxin B total dose is highly related to the risk of AKI, regardless of patient weight. Thirty-day mortality tended to be higher in patients who developed AKI. The relationship between dose, AKI and mortality must be further investigated in studies specifically designed to evaluate this latter outcome.
authors.affiliation: Infectious Diseases Service, Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Maria Helena
authors.initials: MH
authors.lastname: Rigatto
authors.affiliation: Infectious Diseases Service, Hospital de Clínicas de Porto Alegre, 2350 Ramiro Barcelos St., Porto Alegre 90.035-903, Brazil.
authors.forename: Tainá F
authors.initials: TF
authors.lastname: Behle
authors.affiliation: Infection Control Service, Hospital Nossa Senhora da Conceição, Porto Alegre, Brazil.
authors.forename: Diego R
authors.initials: DR
authors.lastname: Falci
authors.affiliation: Infection Control Service, Hospital Nossa Senhora da Conceição, Porto Alegre, Brazil.
authors.forename: Thiela
authors.initials: T
authors.lastname: Freitas
authors.affiliation: Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Natane T
authors.initials: NT
authors.lastname: Lopes
authors.affiliation: Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Mariá
authors.initials: M
authors.lastname: Nunes
authors.affiliation: Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Leonardo W
authors.initials: LW
authors.lastname: Costa
authors.affiliation: Infectious Diseases Service, Hospital de Clínicas de Porto Alegre, 2350 Ramiro Barcelos St., Porto Alegre 90.035-903, Brazil Department of Internal Medicine, Medical School, Universidade Federal do Rio Grande do Sul, Porto, Alegre, Brazil azavascki@hcpa.ufrgs.br.
authors.forename: Alexandre P
authors.initials: AP
authors.lastname: Zavascki
mesh_terms: D058186:Acute Kidney Injury / Q000139:chemically induced* / Q000453:epidemiology* / Q000401:mortality; D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011112:Polymyxin B / Q000009:adverse effects* / Q000627:therapeutic use; D011446:Prospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D011112:Polymyxin B
keywords: PMB; colistin; nephrotoxicity