Validation of Administrative Definitions of Invasive Mechanical Ventilation across 30 Intensive Care Units
Authors: Meeta Prasad Kerlin, Gary E. Weissman, Katherine A. Wonneberger, Saida Kent, Vanessa Madden, Vincent X. Liu, Scott D. Halpern
Journal: American Journal of Respiratory and Critical Care Medicine (2016)

Many insights into the etiology and outcomes of respiratory failure have been gleaned from studies using administrative data (1-3).However, the validity of identifying patients receiving invasive mechanical ventilation (IMV) in such datasets is not well established.One widely cited study in support of claims-based IMV definitions was limited to three centers within one Canadian provincial system and included only 46 ventilated patients (4).Another single-center study addressed only the positive predictive value of administrative definitions (5).We sought to assess a more complete array of operating characteristics for several administrative definitions of IMV and to characterize the patients best identified by these definitions among a larger and more diverse sample. MethodsWe evaluated two populations: (1) 500 randomly selected patients admitted in 2013 to 9 intensive care units (ICUs) within three hospitals affiliated with the University of Pennsylvania Health System (UPHS), and (2) all patients admitted from 2008 through 2013 to 21 ICUs in 21 hospitals in the Kaiser Permanente Northern California (KPNC) integrated healthcare delivery system.Organizationally independent medical, surgical, general, and subspecialty ICUs were selected from the UPHS hospitals, including one quaternary care center, one tertiary care center, and one community hospital with academic affiliation in urban Philadelphia.KPNC hospitals included a mix of community and academically affiliated ICUs, with local and regional organizational structures and diverse patient case mixes.For UPHS patients, we obtained data on use and duration of IMV by hand review of medical charts and hand calculated the Simplified Acute Physiology Score 3 (SAPS3) retrospectively.For KPNC patients, we obtained data on use and duration of IMV on the basis of validated electronic medical record algorithms (6).Electronic SAPS3 scores were calculated retrospectively (7).For all patients, we obtained International Classification of Diseases, Ninth Revision (ICD-9) procedure codes for IMV (96.7x) and endotracheal intubation (96.0x); diagnosis codes for acute respiratory failure (518.51,518.53, 518.81, and 518.84); and Medicare Severity Diagnosis-Related Groups (MS-DRG) codes including intubation, IMV, or tracheostomy (207, 208, 870, 927, 933, 003, and 004) from discharge records.We estimated the operating characteristics for each category of codes individually and in combinations.We compared age, sex, ICU length of stay, duration of IMV, SAPS3, medical or surgical status, and in-hospital mortality among patients correctly identified as mechanically ventilated (true positives) versus those incorrectly identified as not ventilated (false negatives) using chi-square, Wilcoxon rank-sum, and t tests as appropriate.All statistical analyses were performed using Stata 14.1 (StataCorp, College Station, TX). Results