Surgery for Obesity and Related Diseases ] (2018) 00–00 Letter to the editor Response to letter to the editor: impact of bariatric surgery on outcomes of patients with nonalcoholic fatty liver disease: a nationwide inpatient sample analysis, 2004–2012 To the editor: We thank Drs. Juo, Sanaiha, and Chen for their insight- ful comments regarding our recent findings concerning the impact of bariatric surgery on clinically relevant outcomes in patients with nonalcoholic fatty liver disease (NALFD) [1]. Given the current parallel rise in prevalence of both NAFLD and obesity, consideration for effective weight loss strategies and bariatric surgery is of incredible importance in this select patient population. Therefore, we feel our findings, while limited by study design, are highly relevant to both the medical and surgical community caring for these patients. With regard to our methodologic design, the Nationwide Inpatient Sample database has been previously validated for NAFLD and bariatric surgery, and our findings were comparable to previously reported non-NAFLD surgical trends [2–4]. We share the authors’ concerns about use of the Nationwide Inpatient Sample database and their belief that caution should be used with interpretation of such data. It is our belief as well that studies using the Nationwide Inpatient Sample database have the ability to provide paramount themes and propose clinically relevant questions that require further investigation. Ultimately, we concur that prospectively collected studies are needed to stratify NAFLD patients best suited for bariatric surgery and definitively guide future practice patterns. However, the ability of large observational studies to draw important and meaningful conclusions should not be entirely dismissed [5]. To summarize our results, prior bariatric surgery was found to be associated with a decreased in-hospital morbidity and mortality in morbidly obese patients with NAFLD. Despite the inherent limitations of observa- tional, retrospectively collected data and lack of long- term follow-up, we feel this study provides potential powerful information regarding clinically relevant out- comes of bariatric surgery in NAFLD patients. Thomas R. McCarty, M.D. Department of Internal Medicine Yale University School of Medicine New Haven, Connecticut Justin B. Echouffo-Tcheugui, M.D., Ph.D. Division of Endocrinology Diabetes and Hypertension Brigham and Women’s Hospital Boston, Massachusetts Andrew Lange, M.D. Department of Internal Medicine Yale University School of Medicine New Haven, Connecticut Lamia Haque, M.D., M.P.H. Section of Digestive Diseases Yale University School of Medicine New Haven, Connecticut Basile Njei, M.D., M.P.H. Investigative Medicine Program Yale Center of Clinical Investigation New Haven, Connecticut References [1] McCarty TR, Echouffo-Tcheugui JB, Lange A, Haque L, Njei B. Impact of bariatric surgery on outcomes of patients with nonalcoholic fatty liver disease: a nationwide inpatient sample analysis, 2004–2012. Surg Obes Relat Dis 2018;14(1):74–80. [2] Khan S, Rock K, Baskara A, Qu W, Nazzal M, Ortiz J. Trends in bariatric surgery from 2008 to 2012. Am J Surg 2016;211(6):1041–6. [3] Angrisani L, Santonicola A, Iovino P, Formisano G, Buchwald H, Scopinaro N. Bariatric Surgery Worldwide 2013. Obes Surg 2015;25(10):1822–32. [4] Calzadilla Bertot L, Adams LA. The natural course of non-alcoholic fatty liver disease. Int J Mol Sci 2016;17(5):E774. [5] Concato J, Shah N, Horwitz RI. Randomized, controlled trials, observational studies, and the hierarchy of research designs. N Engl J Med 2000;342(25):1887–92. https://doi.org/10.1016/j.soard.2018.02.020 https://doi.org/10.1016/j.soard.2018.02.020 1550-7289/ r 2018 Published by Elsevier Inc. on behalf of American Society for Metabolic and Bariatric Surgery.