title: Validation of Intensive Care and Mechanical Ventilation Codes in Medicare Data.
abstract: OBJECTIVE
  To assess the reliability of codes relevant to critically ill patients in administrative data.
  
  
  METHODS
  Retrospective cohort study linking data from Acute Physiology and Chronic Health Evaluation Outcomes, a clinical database of ICU patients with data from Medicare Provider Analysis and Review. We linked data based on matching for sex, date of birth, hospital, and date of admission to hospital.
  
  
  METHODS
  Forty-six hospitals in the United States participating in Acute Physiology and Chronic Health Evaluation Outcomes.
  
  
  METHODS
  All patients in Acute Physiology and Chronic Health Evaluation Outcomes greater than or equal to 65 years old who could be linked with hospitalization records in Medicare Provider Analysis and Review from January 1, 2009, through September 30, 2012.
  
  
  RESULTS
  Of 62,451 patients in the Acute Physiology and Chronic Health Evaluation Outcomes dataset, 80.1% were matched with data in Medicare Provider Analysis and Review. All but 2.7% of Acute Physiology and Chronic Health Evaluation Outcomes ICU patients had either an ICU or coronary care unit charge in Medicare Provider Analysis and Review. In Acute Physiology and Chronic Health Evaluation Outcomes, 37.0% received mechanical ventilation during the ICU stay versus 24.1% in Medicare Provider Analysis and Review. The Medicare Provider Analysis and Review procedure codes for mechanical ventilation had high specificity (96.0%; 95% CI, 95.8-96.2), but only moderate sensitivity (58.4%; 95% CI, 57.7-59.1), with a positive predictive value of 89.6% (95% CI, 89.1-90.1) and negative predictive value of 79.7% (95% CI, 79.4-80.1). For patients with mechanical ventilation codes, Medicare Provider Analysis and Review overestimated the percentage with a duration greater than 96 hours (36.6% vs 27.3% in Acute Physiology and Chronic Health Evaluation Outcomes). There was discordance in the hospital discharge status (alive or dead) for only 0.47% of all linked records (κ = 1.00).
  
  
  CONCLUSIONS
  Medicare Provider Analysis and Review data contain robust information on hospital mortality for patients admitted to the ICU but have limited ability to identify all patients who received mechanical ventilation during a critical illness. Estimates of use of mechanical ventilation in the United States should likely be revised upward.
authors.affiliation: 1Department of Critical Care Medicine, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.2Prescient Healthcare Consulting, Charlottesville, VA.3Department of Medicine (Critical Care), Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Hannah
authors.initials: H
authors.lastname: Wunsch
authors.forename: Andrew
authors.initials: A
authors.lastname: Kramer
authors.forename: Hayley B
authors.initials: HB
authors.lastname: Gershengorn
mesh_terms: D018806:APACHE; D000368:Aged; D000369:Aged, 80 and over; D059019:Clinical Coding / Q000592:standards*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data*; D007362:Intensive Care Units / Q000592:standards*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D014481:United States