Employees are worrying about the cost impact of changes that employers have been making to insurance coverage in employee benefit plans, Colonial Life & Accident Insurance Company reports.

Among full-time employees, 86% are at least somewhat concerned about unexpected medical expenses, says Colonial Life, Columbia, S.C., citing an April 2009 survey it has just released.

In addition, 83% are concerned about increased premiums and expenses no longer covered by their plan; 81% about the addition of or increases in deductible amount; and 79% about the addition of or increases in their copay.

Conducted by Harris Interactive, the survey sampled more than 1,000 U.S. adults age 18 and over who were enrolled in an insurance program that has changed in the last year. The insurance plans were provided by employers or by spouses’ coverage.

Nearly half reported seeing changes in their coverage since 2008, Colonial says. Of these, 65% reported increased premiums; 56%, the addition of or increase in copay amounts; and 48%, the addition of or increases in deductibles.

The survey found that 78% of surveyed employees were at least somewhat interested in purchasing supplemental coverage or voluntary benefits to help pay for some of the expenses not currently covered by their insurance plans.