SEATTLE – A new national report shows U.S. residents enrolled in employer-sponsored health plans will cover an average of 41 percent of their families’ health care costs this year, the largest share to date, with increased premium contributions rising by 14.7 percent from 2008.

The report, the fifth annual Milliman Medical Index, measures average annual medical spending for a typical American family of four covered by an employer-sponsored preferred provider organization (PPO) plan – the most common type nationally and in Rhode Island.

Milliman looked at PPOs in 14 major metropolitan areas and found that on average, total medical costs for a typical family of four in 2009 are expected to reach $16,771, 7.4 percent higher than in 2008. Employers are expected to pay $9,947 of that, and employees will pay $4,004 toward their premiums and another $2,820 out of pocket for copayments, deductibles, etc.

Though overall costs continue to rise, for the third year in a row, growth in costs is slowing down, Milliman found. Still, the $1,162 increase is the highest since the 2006 increase of $1,169.

This is the third consecutive double-digit percentage increase in the amount that employees spend on health care, the report notes, and it’s primarily due to premium contributions, which grew by 10.1 percent from 2007 to 2008 and 12.8 percent from 2006 to 2007. Employers’ share of premiums rose by 6.5 percent in 2007, 6 percent in 2008 and 5.4 percent this year.

A key point of the report is that the economy is making a big impact on health care spending, affecting utilization in ways that could reduce costs – such as postponed or avoided elective procedures – but also imposing extra costs in other ways.

“Among lost jobs, lost revenue, strained government budgets, consumer insecurity and an uncertain future, the macroeconomic climate is affecting health care costs,” said study co-author Lorraine Mayne, a principal at Milliman and a consulting actuary. “Throw in health care reform and you have a cost trend environment unlike any we’ve seen in recent memory.”

Milliman is one of the world’s largest independent actuarial and consulting firms, with offices in 49 locations nationwide. To read the report online or download a PDF version, go to the Milliman Web site.