title: How valid is the AHRQ Patient Safety Indicator "postoperative physiologic and metabolic derangement"?
abstract: BACKGROUND
  The Agency for Healthcare Research and Quality Patient Safety Indicator postoperative physiologic and metabolic derangement (PMD) uses ICD-9-CM codes to screen for potentially preventable acute kidney injury (AKI) requiring dialysis plus diabetes-related complications after elective surgery. Data on PMD's accuracy in identifying true events are limited. We examined the indicator's positive predictive value (PPV) in the Veterans Health Administration (VA).
  
  
  METHODS
  Trained abstractors reviewed medical records of 119 PSI software-flagged PMD cases. We calculated PPVs overall and separately for renal- and diabetes-related complications. We also examined false positives to determine reasons for incorrect identification, and true positives to determine PMD-related outcomes and risk factors.
  
  
  RESULTS
  Overall 75 cases were true positives (PPV 63%, 95% CI 54% to 72%); 73 of 104 AKI cases were true positives (PPV 70%, 60% to 79%); only 2 of 15 diabetes cases were true positives (PPV 13%, 2% to 40%). Of all false positives, 70% represented nonelective admissions and 23% had the complication present on admission. Of AKI true positives, 37% died and 26% were discharged on dialysis; 55% had chronic kidney disease (≥ stage 3) present on admission. Cardiac surgery represented the largest category of AKI-associated index procedures (30%). AKI was most commonly attributed to perioperative renal hypoperfusion (84% of true positives), followed by nephrotoxins (33%) including contrast (11%).
  
  
  CONCLUSIONS
  Due to its low PPV, we recommend removing diabetes complications from the indicator and focusing on AKI. PMD's PPV could be significantly improved by using present-on-admission codes, and specific to the VA, by introduction of admission status codes. Many PMD-identified cases appeared to be at high risk based on patient- and procedure-related factors. The degree to which such cases are truly preventable events requires further assessment.
authors.affiliation: Center for Health Quality, Outcomes and Economic Research, Bedford VAMC, Bedford, MA, Boston, MA, USA. amb@bu.edu
authors.forename: Ann M
authors.initials: AM
authors.lastname: Borzecki
authors.forename: Marisa
authors.initials: M
authors.lastname: Cevasco
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.forename: Marlena
authors.initials: M
authors.lastname: Shin
authors.forename: Kamal M F
authors.initials: KM
authors.lastname: Itani
authors.forename: Amy K
authors.initials: AK
authors.lastname: Rosen
mesh_terms: D058186:Acute Kidney Injury / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D000368:Aged; D059019:Clinical Coding / Q000592:standards; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D048909:Diabetes Complications / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D005189:False Positive Reactions; D005260:Female; D006302:Health Services Research; D006787:Hospitals, Veterans / Q000706:statistics & numerical data*; D006801:Humans; D007297:Inpatients; D008297:Male; D019300:Medical Errors / Q000517:prevention & control / Q000706:statistics & numerical data; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D015588:Observer Variation; D011183:Postoperative Complications / Q000453:epidemiology* / Q000517:prevention & control; D011237:Predictive Value of Tests; D019984:Quality Indicators, Health Care / Q000592:standards* / Q000639:trends; D015203:Reproducibility of Results; D012107:Research Design; D012189:Retrospective Studies; D012307:Risk Factors; D017751:Safety Management / Q000592:standards*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology