A report from California State Auditor Elaine Howle on Tuesday found that specialty health care for prisoners cost the state $734 million in 2007-08, a figure that advocates say bolsters the case for a medical parole system for incapacitated inmates.

The audit also found that just one-half of 1 percent of the prisoners during that fiscal year, or 1,175 inmates, incurred 39 percent of the specialty health care costs. Moreover, the audit found nearly 32 percent of health-related overtime costs, or $136 million, were related to guarding and transporting inmates for care.

Ways to reduce prison health costs could include "a review of the program that allows for the early release of terminally ill or medically incapacitated inmates, and other possible means of altering the ways in which inmates are housed without unduly increasing the risk to the public," the audit said.

The state Senate Appropriations Committee approved a bill Monday by Sen. Mark Leno, D-San Francisco, that would set up a medical parole system specifically for inmates who are in a vegetative or highly incapacitated condition. The measure is awaiting a vote on the Senate floor.

The prison health system has identified 21 inmates whose average annual health care and guard costs total more than $1.97 million each for a total of $41.4 million a year. Leno said the number of inmates who would qualify for medical parole under his bill may be even higher.