Many thought that the low costs of generic drugs would decrease the co-pays for formulary and non-formulary prescription drugs. Yet, new research shows formulary and non-formulary co-pays have increase by at least 20% on all plan types over the last five years.

Analyzing more than 5,400 benefit plans, Compdata Surveys, a compensation and benefits survey data provider, found formulary co-pays were more than $24.00 on all plan types with PPO plans having the highest co-pay, $25.31.

Moreover, the surveys found prices on non-formulary co-pays were above $39.00 for all plan types, and the average co-pay on PPO plans was $42.31.

Since 2003, formulary co-pays on all plan types have jumped by at least 24%, with indemnity plans seeing the largest increase (30.4%), followed by HMOs (27.5%). PPO plans, however, had the smallest increase (24.6%), the data indicates.

While non-formulary drugs on HMO plans had a 20.1% increase over the last five years, other plan types had growth above 27%. For instance, indemnity plans had the highest increase at 36%, while PPO and POS plans faced an upsurge of 27.6% and 27.7%, respectively. The research on prescription co-pays covered almost 6 million employees.

Analysts at Compdata report generic prescription co-pay costs range between $10.56 and $11.25, while generic co-pays on PPO plans are $10.99.

When comparing the generic price to the non-formulary price on PPO plans, analysts saw a difference of $31.32. For prescriptions used monthly, the difference can equate to $375.84 for just one prescription over the course of a year.

"Employers should be proactive in educating employees regarding prescription costs," says Amy Kaminski, manager of marketing programs for Compdata Surveys. "Offering a formulary list to your employees allows them to see how drugs are classified, so they can make informed choices when working with their physician," she adds.