Leadership Team
The legacy and collaboration of our leadership sets us apart. This team has dedicated their careers to creating the best organization where providers can thrive.

Mark Gilreath
Chief Executive Officer
Mark Gilreath brings more than 27 years of operational leadership, innovation, and GI experience to United Digestive’s executive team. As former operating partner for Frazier Healthcare Partners, he facilitated the formation of United Digestive in 2018.

Neal C. Patel, MD
Chief Strategy Officer
Prior to assuming the role of Chief Strategy Officer, Dr. Neal C. Patel served as Vice President of Clinical Development at United Digestive. He currently also is a partner physician and serves as a member of the physician executive committee for Atlanta Gastroenterology Associates. In addition, he is a board member of the Digestive Health Provider Association, an organization comprised of over 96 independent GI practices from across the nation.

John Suh, MD, MPH
Chief Medical Officer
Prior to serving as chief medical officer at United Digestive, Dr. John Suh held various leadership roles within the organization and affiliated practice, Atlanta Gastroenterology Associates. He served as a member of United Digestive’s inaugural physician executive committee, on the orgnaization’s endoscopy governing body, and continues to serve as medical director for the organization’s Advanced Center for GI Therapeutics. In addition, he is a former board member of the Digestive Health Provider Association, an organization comprised of independent GI practices from across the nation.

Rita Odisho
Chief Financial Officer
Rita Odisho brings more than 25 years of healthcare, M&A, and practice management experience – both publicly-held and private equity-owned – to United Digestive’s executive team. As a financial and operational leader, Rita has extensive experience in mergers and acquisitions, revenue cycle management, practice integration, and running multi-state operations serving hundreds of clinicians. In addition, she is Lean Six Sigma certified with proven experience in building high-performing teams.

Edward L. Hay, Jr., MHA, FACHE
Chief Operations Officer
Edward brings more than 32 years of operations and physician practice management experience to United Digestive, including expertise in strategic planning, governance, recruiting and retention, referral management, and revenue cycle infrastructure.
Previously, Edward worked for Optum/The Advisory Board Company/Southwind for 12 years where he served in various key executive roles and provided group practice assessment and strategic planning to health systems and medical group enterprises. Most recently, he served as Senior Vice President of Operations for ProHEALTH New York, a 1,000-clinician medical group. He oversaw all practice operations, urgent care, radiology, pathology, anesthesia, ambulatory surgery center, and all centralized practice services (call center, health information management, and referral management).

Sam Vaill
Chief Development Officer
Sam brings nearly 20 years of experience in business development, healthcare, mergers & acquisitions, private equity, and investment banking to the United Digestive executive team.
Most recently, Sam served as Chief Growth Officer for Sequel Youth & Family Services, one of the largest national providers of residential and community-based behavioral health services for children, adolescents, and adults. He oversaw various business development teams and was responsible for organic growth, mergers & acquisitions, and de novo expansion. Sam was also responsible for helping start and set the strategy for their new Autism division.

Leslie Graham
Vice President, Human Resources
Leslie Graham brings more than 20 years of human resources, employee engagement, and talent management experience to United Digestive’s executive team. Most recently, Leslie served as the director of people services for DaVita Dialysis providing expertise in the areas of leadership executive coaching, human resources operations strategy, leadership development, and performance management.
Board of Directors
A culture of collaboration and accountability starts at the top. Our board of directors is comprised of cross-functional business and clinical leaders who help guide our organization and ensure we continue to accomplish our goals.
Physician Executive Committee
With a dynamic and engaged provider base, our physician executive committee serves as the voice for their local colleagues and helps guide the clinical side of the organization. Members are elected by their peers, represent our various geographic regions, and meet regularly with United Digestive’s leadership team.