Letters to the EditorValidation of the Combined Comorbidity Index of Charlson and Elixhauser to Predict 30-Day Mortality Across ICD-9 and ICD-10Sun, Jenny W. SM*,†; Rogers, James R. MS‡; Her, Qoua PharmD, MS, MSc§; Welch, Emily C. MPH§; Panozzo, Catherine A. PhD§; Toh, Sengwee ScD†,§; Gagne, Joshua J. PharmD, ScD*,†Author Information *Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School †Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA ‡Department of Biomedical Informatics Columbia University, New York, NY §Department of Population Medicine Harvard Medical School and Harvard Pilgrim Health Care Institute Boston, MA J.J.G. is Principal Investigator of grants from Eli Lilly and Company and Novartis Pharmaceuticals Corporation to the Brigham and Women’s Hospital and is a consultant to Aetion Inc. and to Optum Inc., all for unrelated work. J.R.R. has been a consultant to Aetion Inc. for unrelated work. The remaining authors declare no conflict of interest. Medical Care: September 2018 - Volume 56 - Issue 9 - p 812 doi: 10.1097/MLR.0000000000000954 Buy Metrics Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.