title: Predictors of clinical success among a national Veterans Affairs cohort with methicillin-resistant Staphylococcus aureus pneumonia.
abstract: BACKGROUND
  The treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is exceedingly complicated, which is concerning because of the high mortality rate associated with the infection. Identification of independent predictors of clinical success can optimize patient care by assisting clinicians in treatment decisions.
  
  
  OBJECTIVE
  Our goal was to identify independent predictors of clinical success in a national Veterans Affairs (VA) cohort of patients with MRSA pneumonia.
  
  
  METHODS
  A nested case-control study was conducted among a cohort of VA patients with MRSA pneumonia receiving linezolid or vancomycin between January 2002 and September 2010. Cases included those demonstrating clinical success, defined as discharge from the hospital or intensive care unit by day 14 after treatment initiation, in the absence of death, therapy change, or intubation by day 14. Control subjects represented nonsuccess, defined as therapy change, intubation, intensive care unit admission, readmission, or death between treatment initiation and day 14. The potential predictors assessed included treatment, patient demographic and admission characteristics, previous health care and medication exposures, comorbidities, and medical history. Odds ratios (ORs) and 95% CIs were calculated from logistic regression.
  
  
  RESULTS
  Our study included 2442 cases of clinical success and 1290 control subjects. Demographic characteristics varied between the clinical success and nonsuccess groups, including age, race, and region of facility. A current diagnosis of chronic respiratory disease (46% vs 42%) and diagnosis of pneumonia in the year before the MRSA pneumonia admission (37% vs 32%) were both more common in the clinical success group. Despite these significant differences, only 2 predictors of clinical success were identified in our study: previous complication of an implant or graft, including mechanical complications and infections, in the year before the MRSA pneumonia admission (adjusted OR, 1.55 [95% CI, 1.17-2.06]) and treatment with linezolid (adjusted OR, 1.53 [95% CI, 1.12-2.10]). Predictors of nonsuccess (adjusted OR [95% CI) included diagnosis of concomitant urinary tract infection (0.82 [0.70-0.96]), intravenous line (0.76 [0.66-0.89]), previous coagulopathy (0.74 [0.56-0.96]), previous amputation procedure (0.72 [0.53-0.98]), current coagulopathy diagnosis (0.71 [0.53-0.96]), dialysis (0.54 [0.38-0.76]), multiple inpatient procedures (0.53 [0.45-0.62]), inpatient surgery (0.48 [0.41-0.57]), and previous endocarditis (0.24 [0.07-0.81]).
  
  
  CONCLUSIONS
  MRSA pneumonia tends to affect patients with complex care, and identification of the predictors of clinical success is useful when considering different therapeutic approaches. In this national cohort of VA patients with MRSA pneumonia, treatment was the only modifiable variable predicting clinical success.
authors.affiliation: Veterans Affairs Medical Center, Infectious Diseases Research Program, Providence, Rhode Island; University of Rhode Island, College of Pharmacy, Kingston, Rhode Island.
authors.forename: Aisling R
authors.initials: AR
authors.lastname: Caffrey
authors.affiliation: Veterans Affairs Medical Center, Infectious Diseases Research Program, Providence, Rhode Island; University of Rhode Island, College of Pharmacy, Kingston, Rhode Island.
authors.forename: Haley J
authors.initials: HJ
authors.lastname: Morrill
authors.affiliation: Pfizer Inc, Collegeville, Pennsylvania.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Puzniak
authors.affiliation: Veterans Affairs Medical Center, Infectious Diseases Research Program, Providence, Rhode Island; University of Rhode Island, College of Pharmacy, Kingston, Rhode Island; Warren Alpert Medical School of Brown University, Division of Infectious Diseases, Providence, Rhode Island. Electronic address: kerrylaplante@uri.edu.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: LaPlante
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D007362:Intensive Care Units; D000069349:Linezolid / Q000627:therapeutic use*; D016015:Logistic Models; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D016017:Odds Ratio; D011023:Pneumonia, Staphylococcal / Q000188:drug therapy* / Q000382:microbiology; D016896:Treatment Outcome; D014481:United States; D014640:Vancomycin / Q000627:therapeutic use*; D014728:Veterans
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D000069349:Linezolid
keywords: linezolid; methicillin-resistant Staphylococcus aureus; pneumonia; predictors of clinical success; vancomycin