Medical homes in the Southeastern Pennsylvania Chronic Care Initiative also didn't save on costs compared with normal primary care practices. Instead, the homes accumulated bonuses of $92,000 per physician during a three-year pilot program, according to the study released today in the Journal of the American Medical Association.

Medical homes have gained popularity as health-care costs rise in the U.S. and the population ages. A physician-led team focuses on comprehensive and continuous care such as calling patients to remind them to take their medication and schedule follow-up visits. Medical homes also coordinate care among specialists, hospitals, and nursing homes.

"The findings were surprising," Mark Friedberg, the lead study author and a scientist at the Rand Corp., a nonprofit research institute based in Santa Monica, California, said in a phone interview. "Expectations for the medical-home model were quite high and this was not consistent with previous findings."