Health Savings Accounts rule among employers who offer a consumer-driven health plan, a new survey finds.

The survey, released by Aon Consulting and the International Society of Certified Employee Benefit Specialists, found that 44% of survey participants offer CDHPs, up from 28% in 2006.

Of those offering CDH plans this year, 56% are using the HSA model, while 35% of organizations are using the Health Reimbursement Arrangements model, and 9% are using both.

HSA use has risen from 48% to 56% in the last three years, while HRA use has fallen from 43% to 35% over the time period, the survey found.

“HSAs have grown in popularity relative to HRAs since HSAs are considered more advantageous to the employee than an HRA,” said John Zern, U.S. health and benefits practice director with Aon Consulting.

Zern said HSAs appeal to employees because they can contribute their own money and own the plan, giving them portability. HSAs also have tax advantages, he said.

Additionally, the survey found the majority of employers (83%) offer the HSA or HRA as an optional plan, while the remaining 17% have implemented a total replacement CDH program where the only plan choices offered to employees are CDHPs.

“Although only 17% of employers offer a total replacement CDH program, we expect that number to increase next year,” said Bill Sharon, national consumer -driven health care practice leader with Aon Consulting. “In response to the economic downturn and double digit health care cost increases, employers are becoming more aggressive in managing their health care costs. Implementing a total replacement CDH program is one of the leading health care strategies available to employers.”

The survey, based on 370 organizations who responded, also found that more employers who offer the HSA plan are contributing money to the plan (66%, up from 60% last year).

Employers offering an HRA plan make a wide variety of contributions to the account for a single employee: 4% provide less than $300; 11% provide between $300 and $499; 49% provide between $500 and $799; 1% provide between $800 and $999; and 34% provide $1,000 or more.

Similar to last year, employers currently offering a CDHP are mainly seeking to control health-plan costs (38%) or to introduce “consumer engagement” into the purchasing of health care for long-term change (35%). Other reasons include: expanding employee choices (14%), encouraging better use of health care services (9%), and providing a vehicle for retiree medical savings (3%).

The survey found 63% of employers have more than 10% of their employees participating in a CDHP, which is similar to last year, but higher than three years ago when 53% had more than one-in-10 in a CDHP.

While 56% of all employers surveyed are not currently offering a CDH plan, 37% of respondents say they plan to offer one in the near future. Of this group, 6% are planning to offer one this year or next; 31% are undecided on an effective date; and 62% are not seriously considering a CDHP as a future plan offering.