title: Postoperative mortality and pulmonary complication rankings: how well do they correlate at the hospital level?
abstract: BACKGROUND
  Postoperative mortality rankings are used alone for quality assessment.
  
  
  OBJECTIVE
  To determine the correlation between hospital rankings of postoperative respiratory failure, pneumonia, and mortality rates and to assess the influence of hospital volume, type of surgery, and time on these correlations. To compare hospital outlier detection with and without pulmonary complication rates.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  103,176 noncardiac surgery patients from 123 VA hospitals enrolled between 1/1/94 and 8/31/95. Preoperative pneumonia, ventilator dependent, comatose, or do-not-resuscitate patients were excluded.
  
  
  METHODS
  Respiratory failure was defined as greater than 48 hours of ventilator assistance or postoperative reintubation. Pneumonia was defined as positive sputum cultures with antibiotic treatment or chest x-ray infiltrate diagnosed as pneumonia or pneumonitis. Mortality was defined as death within 30 days of surgery. Hospital rankings were assigned using risk-adjusted observed-to-expected ratios.
  
  
  RESULTS
  There was significant, but weak correlation between mortality and pulmonary complication rankings (r = 0.21, P = 0.02 for pneumonia; r = 0.22, P = 0.01 for respiratory failure). Correlations with mortality rankings were highest for thoracic (r = 0.42, P < 0.001 for pneumonia; r = 0.38, P < 0.001 for respiratory failure) and vascular surgery (r = 0.26, P = 0.02 for pneumonia; r = 0.35, P < 0.001 for respiratory failure). Supplementing mortality with pulmonary complication outlier designations enhanced outlier detection for 47% of hospitals overall, and for 29% in the lowest caseload quartile.
  
  
  CONCLUSIONS
  Pulmonary complication rankings correlate weakly with mortality overall, but have higher correlations in thoracic, vascular, and upper abdominal surgery. Examining pneumonia and respiratory failure outlier status with mortality outlier status enhances hospital outlier detection even in low-volume hospitals.
authors.affiliation: Veterans Affairs Chicago Healthcare System, Westside Division, Section of General Internal Medicine, University of Illinois College of Medicine, Chicago, Illinois 60612, USA. arozulla@uic.edu
authors.forename: Ahsan M
authors.initials: AM
authors.lastname: Arozullah
authors.forename: William G
authors.initials: WG
authors.lastname: Henderson
authors.forename: Shukri F
authors.initials: SF
authors.lastname: Khuri
authors.forename: Jennifer
authors.initials: J
authors.lastname: Daley
mesh_terms: D000005:Abdomen / Q000601:surgery; D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006787:Hospitals, Veterans / Q000592:standards*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011014:Pneumonia / Q000453:epidemiology*; D011183:Postoperative Complications / Q000453:epidemiology*; D011446:Prospective Studies; D019984:Quality Indicators, Health Care; D012131:Respiratory Insufficiency / Q000453:epidemiology*; D020379:Risk Adjustment; D019616:Thoracic Surgical Procedures / Q000401:mortality; D014481:United States / Q000453:epidemiology; D014656:Vascular Surgical Procedures / Q000401:mortality