Tenet Healthcare Corporation (together with our subsidiaries, referred to herein as "Tenet," "we" or "us") is a national, diversified healthcare services company. We operate regionally focused, integrated healthcare delivery networks, primarily in large urban and suburban markets. Through our subsidiaries, partnerships and joint ventures, including USPI Holding Company, Inc. ("USPI"), at December 31, 2018, we operated 68 hospitals (three of which we have since divested), 23 surgical hospitals and approximately 475 outpatient centers throughout the United States. In addition, our Conifer Holdings, Inc. ("Conifer") subsidiary provides healthcare business process services in the areas of hospital and physician revenue cycle management and value-based care solutions to healthcare systems, as well as individual hospitals, physician practices, self-insured organizations, health plans and other entities. For financial reporting purposes, our business lines are classified into three separate reportable operating segments - Hospital Operations and other, Ambulatory Care and Conifer. Additional information about our business segments is provided below; statistical data for the segments can be found in Item 7, Management's Discussion and Analysis of Financial Condition and Results of Operations, of Part II of this report.
We are focused on improving operational effectiveness, increasing capital efficiency and margins, expanding patient access points, enhancing the customer care experience in every part of our operations, and growing our higher-acuity inpatient service lines, as well as aligning service line growth with community demand. We believe our inpatient admissions have been constrained in recent years by increased competition, utilization pressure by managed care organizations, new delivery models that are designed to lower the utilization of acute care hospital services, the effects of higher patient co-pays, co-insurance amounts and deductibles, changing consumer behavior, and adverse economic conditions and demographic trends in certain of our markets. However, we also believe that emphasis on higher-demand clinical service lines (including outpatient services), focus on expanding our ambulatory care business, cultivation of our culture of service, participation in Medicare Advantage health plans that are experiencing higher growth rates than traditional Medicare plans, and contracting strategies that create shared value with payers should help us grow our patient volumes over time.
We continue to exit service lines, businesses and markets that we believe are no longer a core part of our long-term growth strategy. To that end, in 2018 we divested eight hospitals in the United States, as well as all of our operations in the United Kingdom. In addition, in January 2019, we completed the previously announced sale of three hospitals in the Chicago area that we owned at December 31, 2018. We intend to continue to further refine our portfolio of hospitals and other healthcare facilities when we believe such refinements will help us improve profitability, allocate capital more effectively in areas where we have a stronger presence, deploy proceeds on higher-return investments across our business, enhance cash generation and lower our ratio of debt-to-Adjusted EBITDA.