Providers
Your primary care team
Our clinicians practice evidence-informed medicine and coordinate with nurses and specialists—so your referrals, labs, and prescriptions stay aligned and you always know what’s next.
Sandra Mele, D.O.
Dr. Sandra Mele is a dual board-certified hospitalist and the founding owner of East Valley Integrated Hospitalists. A graduate of an Arizona medical program, she blends bedside expertise with operational excellence and a clear focus on patient safety. Dr. Mele also serves as Program Director for the Internal Medicine Residency at Mountain Vista Medical Center, mentoring residents and coordinating quality initiatives across the Valley. Her leadership emphasizes evidence-based care, reliable communication, and smooth transitions between inpatient and outpatient settings. She partners closely with nurses, advanced practice clinicians, and primary care teams to align plans and reduce readmissions. Patients and colleagues describe her approach as steady, practical, and team-forward—aimed at delivering safe care today while improving the system for tomorrow.
Preston Ashby, D.O.
Dr. Preston Ashby is a hospitalist with EVI Hospitalists known for safe, timely inpatient care and dependable transitions home. He works closely with bedside nurses, therapists, and primary care clinicians to align goals, prevent delays, and reduce avoidable readmissions. His interests include medication safety, discharge readiness, and clear family communication at the bedside and after discharge. Dr. Ashby helps design rounding workflows that prioritize high-risk patients and early mobility while maintaining efficiency for the whole team. He contributes to resident teaching on practical topics such as reconciling medications, planning follow-up, and writing clear discharge instructions. Patients and staff value his calm manner, attention to detail, and focus on dependable, next-step care everyone can understand and follow.
Nathan Duffin, D.O.
Dr. Nathan Duffin earned his undergraduate degree in Kinesiology from Arizona State University and completed medical training at Midwestern University, followed by an Internal Medicine residency in Sierra Vista, Arizona. Over the past decade he has cared for patients at Mountain Vista Medical Center, where he also serves as Assistant Program Director for the Internal Medicine Residency. At EVI Hospitalists, Dr. Duffin focuses on compassionate inpatient care, reliable communication with families, and continuity into the outpatient setting. He collaborates with case management and primary care to arrange follow-up, clarify instructions, and reduce readmissions. Dr. Duffin enjoys resident teaching on clinical reasoning and efficient, patient-centered documentation. Outside of medicine, he enjoys hiking, fishing, golf, and time with his wife and four children.