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How to Enroll
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Our Leadership Team
Dr. Donald Aga
Rating is from U.S. News and World Report, a leading publisher of annual authoritative rankings including Best Medicare Plans. Our plan does not have a direct relationship with U.S. News. This award was not given by Medicare. Our overall rating from Medicare for 2019 is 5.0. Our plan’s official CMS Star Rating can be found at
Our Leadership Team
The entire KelseyCare Advantage team is committed to maintaining excellence, respect and integrity in all aspects of our health plan. Our mission is to enhance the lives of KelseyCare Advantage members by providing high quality health care benefits at an affordable price. We invite you to get to know more about the team that has dedicated themselves to this mission.
Marnie Matheny - President
My plan after graduating from Texas A&M University in 1990 was to work at Kelsey-Seybold Clinic to earn some money before going on to law school. Nearly two decades later, I'm still with the Kelsey family as president of KelseyCare Advantage and I couldn't be happier leading such a dynamic and caring group of people. I come to work every day feeling lucky to have found a home with such a wonderful company.
Dr. Donald Aga - Medical Director
I’m a native Texan and I received my bachelor’s degree in chemistry from Baylor University in 1990. I then attended the University of Texas-Health Science Center here in Houston, where I also did my residency in internal medicine. As a physician, I have several roles in the medical community. I’m an assistant professor of internal medicine at the University of Texas-Health Science Center and a clinical instructor of general medicine at Baylor College of Medicine. But, my primary role is caring for patients at Kelsey-Seybold Clinic, which I’ve been doing since 1997. As of 2007, I’ve also joined KelseyCare Advantage as the medical director.
Theresa Devivar - Vice President of Operations
For me, KelseyCare Advantage is all about taking care of our members. When they call us with a concern or a question, I want them to know how much they matter to us. Everyone on our team knows that the goal is providing absolutely the best service possible.
Denise Martinez Jonathan, Pharm D., R.Ph. - Director of Pharmacy Services
After receiving my Doctorate of Pharmacy degree from the University of Houston College of Pharmacy in 2005, I completed my managed care pharmacy practice residency at Kelsey-Seybold Clinic. I enjoyed the experience at Kelsey-Seybold Clinic, so in 2006, I accepted a position as Pharmacy Administrator of Clinical Services for Kelsey-Seybold Clinic and later, in 2008, became the Director of Pharmacy Services for KelseyCare Advantage.
KelseyCare Advantage is offered by KS Plan Administrators, LLC, a Medicare Advantage HMO with a Medicare contract. Enrollment in KelseyCare Advantage depends on contract renewal. You must continue to pay your Medicare Part B premium. This information is not a complete description of benefits. Contact the plan for more information. Limitations, copayments, and restrictions may apply. Benefits, premium and/or copayments/co-insurance may change on January 1 of each year. The Formulary, pharmacy network, and/or provider network may change at any time. You will receive notice when necessary.
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