title: Hospital volume and mortality for mechanical ventilation of medical and surgical patients: a population-based analysis using administrative data.
abstract: OBJECTIVE
  In an effort to improve efficiency and quality of care, regionalization of adult critical care services, similar to trauma and neonatal intensive care, has been suggested. However, there is little research to understand if hospitals with higher patient volumes have better outcomes. Our objective is to determine whether hospital volume is associated with improved survival for medical or surgical patients receiving mechanical ventilation.
  
  
  METHODS
  Population-based retrospective cohort study.
  
  
  METHODS
  Province of Ontario, Canada.
  
  
  METHODS
  A total of 13,846 medical and 6,373 surgical patients receiving mechanical ventilation for greater than two consecutive days between 1998 and 2000.
  
  
  METHODS
  None.
  
  
  METHODS
  Odds ratio for death within 30 days of initiation of mechanical ventilation was calculated in relation to hospital volume of ventilation. Estimates were adjusted for patient demographics, diagnoses, and urgency status; hospital region and rural location; and accounted for clustering within hospitals.
  
  
  RESULTS
  There was no effect of volume on mortality for surgical patients. After adjustment for clustering, among medical patients, the lowest-volume category (<100 episodes/yr) had a nonsignificant increase in mortality, with an odds ratio (95% confidence interval) of 1.13 (0.87-1.47) compared with the highest-volume category (> or =700 episodes/yr). A post hoc analysis revealed that within the lowest-volume category, the proportion of patients transferred to larger hospitals was 81% for hospitals with <20 episodes/yr and only 32% for hospitals with 20-99 episodes/yr, with odds ratios (95% confidence interval) for mortality of 0.74 (0.49-1.12) and 1.18 (0.90-1.54), respectively, compared with the highest-volume category.
  
  
  CONCLUSIONS
  For surgical patients requiring mechanical ventilation for >2 days, hospital volume had no effect on mortality. For medical patients, higher mortality may occur in a subgroup of low-volume hospitals that do not routinely transfer their patients to larger-volume facilities. This finding needs further investigation in a larger-sized study.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Dale M
authors.initials: DM
authors.lastname: Needham
authors.forename: Susan E
authors.initials: SE
authors.lastname: Bronskill
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Rothwell
authors.forename: William J
authors.initials: WJ
authors.lastname: Sibbald
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Pronovost
authors.forename: Andreas
authors.initials: A
authors.lastname: Laupacis
authors.forename: Thérèse A
authors.initials: TA
authors.lastname: Stukel
mesh_terms: D000368:Aged; D015331:Cohort Studies; D016638:Critical Illness; D019992:Databases as Topic; D005260:Female; D017052:Hospital Mortality; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009864:Ontario; D017063:Outcome Assessment, Health Care; D010360:Patient Transfer; D012121:Respiration, Artificial; D012189:Retrospective Studies