In its inaugural report on how hospitals pay doctors for "on-call" coverage, the MD Ranger Inc. consulting firm indicates that trauma hospitals typically pay 30% more than non-trauma hospitals for such services, which once were provided as part of doctors' medical staff duties. And overall, such payments totaled more than $1.6 billion in California hospitals in 2008, according to the study. That represented 3.6% of California hospital expenses in 2008, the most recent year for which data is available, up from 2.7% in 2001, the report found.