While employers may use participation rates in employee assistance programs to measure their return on investment, they need to look behind those figures to determine the true success of their programs, experts caution.

Because there is no standard definition of EAP utilization in the market, EAP vendors use different criteria to show employers how well their programs are being utilized, they say.

For some EAPs, utilization may mean the number of face-to-face counseling sessions. For others, it may mean the number of unique users accessing the program, while others may count every phone call and Web hit in utilization numbers, experts note.

Therefore, employers need to determine how their vendors are measuring utilization and whether that makes sense for their organization.

When an employer says it has a 20% utilization rate, "I'm always very suspicious of that," said Dan Clark, vp and chief marketing officer for Resources for Living L.L.C., an EAP provider based in Austin, Texas. For EAPs that report Web hits in their utilization, one member who calls about two separate issues may be counted as two cases by one EAP while another EAP counts it as one, he said.

"It's important to dig beneath the utilization numbers to see how many unique users you have using the services," Mr. Clark said.

"We see everything out there from 2% to 25% utilization," said Dave Sharar, managing director of Chestnut Global Partners, the wholly owned EAP and workplace services subsidiary of Chestnut Health Systems based in Bloomington, Ill.

Some EAP vendors, he said, count every phone call and Web hit because "when employers look at a report, they want them to think, 'Wow. This program is really getting use,"' Mr. Sharar said.

In reality, though, what may be happening is one man is using the EAP's financial calculator every day for his retirement plan, and that is "hardly robust utilization."

"It tends to be about form and style and not substance," Mr. Sharar said.

"Obviously a program is not going to be successful it it's not being used, but don't assume if your vendor's reporting 15% utilization and your previous vendor had 2% that the 2% wasn't getting you more bang for your buck," Mr. Sharar said.

"It's a problem that we work with clients with all the time," said Sandra Routledge, senior consultant in the group health care practice of Watson Wyatt Worldwide in Vancouver, British Columbia.

"The definition of utilization is very key in terms of meeting the employer's needs and in terms of establishing best practices," Ms. Routledge said.

If keeping employees healthy, productive and on the job is what they hope to accomplish with their EAPs, then employers need to measure whether the employees are dealing with issues early on and whether they have access to the appropriate referral, health and wellness resources, she added.