Background: Out-of-pocket spending has risen for individuals with private health insurance, yet little is known about the unintended consequences that high levels of cost-sharing may have on delayed clinical presentation and financial outcomes for common emergency surgical conditions., Methods: In this retrospective analysis of claims data from a large commercial insurer (2016-2019), we identified adult inpatient admissions following emergency department presentation for common emergency surgical conditions (eg, appendicitis, cholecystitis, diverticulitis, and intestinal obstruction). Primary exposure of interest was enrollment in a high-deductible health insurance plan (HDHP). Our primary outcome was disease severity at presentation-determined using ICD-10-CM diagnoses codes and based on validated measures of anatomic severity (eg, perforation, abscess, diffuse peritonitis). Our secondary outcome was catastrophic out-of-pocket spending, defined by the World Health Organization as out-of-pocket spending >10% of annual income., Results: Among 43,516 patients [mean age 48.4 (SD: 11.9) years; 51% female], 41% were enrolled HDHPs. Despite being younger, healthier, wealthier, and more educated, HDHP enrollees were more likely to present with more severe disease (28.5% vs 21.3%, P <0.001; odds ratio (OR): 1.34, 95% CI: 1.28-1.42]); even after adjusting for relevant demographics (adjusted OR: 1.23, 95% CI: 1.18-1.31). HDHP enrollees were also more likely to incur 30-day out-of-pocket spending that exceeded 10% of annual income (20.8% vs 6.4%, adjusted OR: 3.93, 95% CI: 3.65-4.24). Lower-income patients, Black patients, and Hispanic patients were at highest risk of financial strain., Conclusions: For privately insured patients presenting with common surgical emergencies, high-deductible health plans are associated with increased disease severity at admission and a greater financial burden after discharge-especially for vulnerable populations. Strategies are needed to improve financial risk protection for common surgical emergencies., Competing Interests: This study was not directly funded by any grants or other relationships. However, the authors have the following disclosures, unrelated to the current work: J.W.S. receives funding from the Agency for Healthcare Research and Quality as principal investigator on grant K08-HS028672 and as a co-investigator on grant R01-HS027788. J.W.S. also receives salary support from Blue Cross Blue Shield of Michigan through the collaborative quality initiative known as Michigan Social Health Interventions to Eliminate Disparities (MSHIELD). P.U.N. receives salary funding through the National Clinical Scholars Program at the University of Michigan. A.M.I. receives funding from the Agency for Healthcare Research and Quality as principal investigator on grant R01-HS028606 and is a Principal at HOK architects, a global design and architecture firm. K.W.S. and Z.F. has no disclosures. A.M.F. reported being a consultant for AbbVie, Amgen, Bayer, Centivo, Community Oncology Association, EmblemHealth, Exact Sciences, Health at Scale Technologies, Lilly, Mallinckrodt, MedZed, Merck, Sempre Health, the State of Minnesota, Wellth, and Zansors; receiving research support from the Agency for Healthcare Research and Quality, Boehringer Ingelheim, the Gary and Mary West Health Policy Center, the Laura and John Arnold Foundation, the National Pharmaceutical Council, Patient-Centered Outcomes Research Institute, PhRMA, and the Michigan Department of Health and Human Services; and being coeditor of the American Journal of Managed Care , a member of the Medicare Evidence Development and Coverage Advisory Committee, and a partner in V-BID Health, LLC. J.B.D. is a cofounder of ArborMetrix Inc., a company that makes software for profiling hospital quality and efficiency. The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)