“…The Elixhauser comorbidity index is a set of comprehensive comorbidity measures associated with in-hospital mortality, all-cause mortality, and health care expenditures, designed for the use of large administrative databases and utilized in many prior NIS studies. 10,16,19,20 HACs were defined using CMS-provided criteria by means of International Classification of Disease, ninth revision, Clinical Modification. 8 Outcomes of interest included occurrence of HACs, prolonged length of stay (pLOS), and elevated inpatient costs.…”