Raw health insurance premium rates will be up about 10.4% in 2007, but actual health plan premium rates will increase only 8.2%.

The Sherlock Company, Gwynedd, Pa., is basing that estimate on results of a survey of 72 health plans.

Although rates for comparable coverage will increase 10.4%, changes in plan designs and other “benefits buy-downs” will help employers hold the actual rate increase to 8.2%, Sherlock says.

The underlying medical costs appear to be up about 8.7%, Sherlock estimates.

The rate of increase appears to be highest in the region that includes Alabama, Kentucky, Missouri and Tennessee, and lowest in the region that includes Arkansas, Louisiana, Oklahoma and Texas.