Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies
Authors: Prachi Sanghavi, Anupam B. Jena, Joseph P. Newhouse, Alan M. Zaslavsky
Journal: Annals of Internal Medicine (2016)

Letters5 July 2016Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical EmergenciesPrachi Sanghavi, PhD, Anupam B. Jena, MD, PhD, Joseph P. Newhouse, PhD, and Alan M. Zaslavsky, PhDPrachi Sanghavi, PhDFrom University of Chicago, Chicago, Illinois, and Harvard Medical School, Boston, Massachusetts.Search for more papers by this author, Anupam B. Jena, MD, PhDFrom University of Chicago, Chicago, Illinois, and Harvard Medical School, Boston, Massachusetts.Search for more papers by this author, Joseph P. Newhouse, PhDFrom University of Chicago, Chicago, Illinois, and Harvard Medical School, Boston, Massachusetts.Search for more papers by this author, and Alan M. Zaslavsky, PhDFrom University of Chicago, Chicago, Illinois, and Harvard Medical School, Boston, Massachusetts.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L15-0628 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:Although we agree with Dr. Soumerai that randomized trials of prehospital care would be useful, they are unlikely to be done. In their absence, the best available observational study designs must be used. We disagree with Dr. Soumerai's characterization of all IV designs as weak. Just as applications of the difference-in-differences designs that Dr. Soumerai favors may vary in strength, so too do IV applications.The key untestable assumptions for valid IV analyses are that the instrument affects the dependent variable only through the variable being instrumented for and is uncorrelated with omitted predictors of the outcome (1, ...References1. Angrist JD, Imbens G, Rubin DB. Identification of causal effects using instrumental variables. Journal of the American Statistical Association. 1996;91:444-55. doi:10.2307/2291629 CrossrefGoogle Scholar2. Angrist JD, Pischke JS. Mostly Harmless Econometrics. Princeton, NJ: Princeton Univ Pr; 2008. Google Scholar3. Garabedian LF, Chu P, Toh S, Zaslavsky AM, Soumerai SB. Potential bias of instrumental variable analyses for observational comparative effectiveness research. Ann Intern Med. 2014;161:131-8. [PMID: 25023252]. doi:10.7326/M13-1887 LinkGoogle Scholar4. Li F, Morgan KL, Zaslavsky AM. Balancing covariates via propensity score weighting. arXiv:1404.1785v2 (stat.ME). Accessed at http://arxiv.org/abs/1404.1785v2 on 18 March 2016. Google Scholar Author, Article, and Disclosure InformationAffiliations: From University of Chicago, Chicago, Illinois, and Harvard Medical School, Boston, Massachusetts.Grant Support: By a National Science Foundation Graduate Research Fellowship (Dr. Sanghavi), an Agency for Healthcare Research and Quality grant (1R36HS022798-01; Dr. Sanghavi), and the National Institutes of Health Early Independence Award (1DP5OD017897-01; Dr. Jena).Disclosures: Dr. Jena receives personal fees as a principal consultant to Precision Health Economics. Dr. Newhouse is a director of, and holds equity in, Aetna. Authors not named here have disclosed no conflicts of interest. Disclosures can also be viewed at www.acponline.org/authors/icmje/Conflict OfInterestForms.do?msNum=M15-0557. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoOutcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies Prachi Sanghavi , Anupam B. Jena , Joseph P. Newhouse , and Alan M. Zaslavsky Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies Stephen B. Soumerai Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies Yusuke Tsutsumi , Yasushi Tsujimoto , Yuki Kataoka , and Tatsuyoshi Ikenoue Metrics Cited byPrehospital advanced cardiac life support with a smartphone-based direct medical oversight in a metropolitan city: a before-after population-based studyICoRSI’s comments on WHO’s draft global targets for road safety risk factors 5 July 2016Volume 165, Issue 1Page: 69-70KeywordsAmbulancesDisclosureHealth care qualityHealth services researchInpatientsInstrumental variable analysisMortalityObservational studiesRandomized trialsResearch quality assessment ePublished: 5 July 2016 Issue Published: 5 July 2016 Copyright & PermissionsCopyright © 2016 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...