SPOKANE — The University of Washington’s plan to double the size of its medical school program in Spokane is the most cost-effective way to meet the state’s need for more doctors, according to a new study released Friday.

It’s the latest skirmish in a battle between UW and Washington State University to increase medical education in the state’s second-largest city.

The new study, commissioned by UW, found that Eastern Washington does not have enough residency programs to support a separate medical school.

The study also said the average cost of medical education per student at UW is about $70,000 a year. That’s lower than the estimated $98,000 per student cost at a stand-alone WSU medical school, the study said.

“This study supports our expansion plans and validates the success of what we have been doing in Spokane since we began medical instruction in the city in 2008,” said UW President Michael K. Young.

“We are offering the most cost-effective, most feasible, and most immediate answer to the challenge of producing more physicians for the underserved areas of our state,” Young said. “Our commitment to our students in Spokane and to the community is deep, and we intend to continue to serve the region and expand the UW School of Medicine in Spokane.”

Washington State University President Elson Floyd said WSU remains committed to creating a medical school in Spokane.

“For too long Washington state has produced too few physicians to meet the needs of our state,” Floyd said. “While we welcome the University of Washington’s announcement today about their intention to address part of this shortfall, it is simply not enough.”

Floyd said WSU supports the expansion plans of the University of Washington in Spokane, but “we believe we must also pursue a new medical school.”

The University of Washington study was conducted by Tripp Umbach, which has conducted numerous studies for UW and WSU, as well as many of the nation’s top medical schools and hospitals.

The UW has proposed doubling its Spokane programs from 40 to 80 students per year.

The new report found there is a need for additional residency slots in order to support any expansion of medical education. The shortage of medical residency positions is a national issue.

“The number of medical schools in a state has no correlation to the number of doctors practicing in a state,” said Paul Umbach, who conducted the study. “What is important is the number of medical students and residency positions available in order to retain physicians.”

The UW has an established residency network throughout Washington, and is working to expand that program, the study said.

The new report mirrors a 2010 study, also conducted by Tripp Umbach, which found that expanding the existing UW-led medical program would have an estimated economic impact of $1.6 billion and support 9,000 jobs over a 20-year period in Spokane.

Earlier this month, officials for UW and WSU reached an agreement to go their own ways to address the state’s medical education needs and physician shortage.

Washington State has complained that the state does not produce enough doctors. The lack of doctors is especially acute in rural areas, WSU has said.

The University of Washington is the state’s only public medical school and enrolls 120 Washington students each year. Washington State University has said it will seek accreditation and funding to open a medical school that will also eventually enroll 120 students per year.