Researchers at Towers Perrin Inc. have developed a system that employers can use to analyze the quality and cost efficiency of their prescription plan drug lists.

The new Towers Perrin Reference Formulary System is unusual because it was developed by an independent consulting firm, not by a pharmacy benefit manager that might have a financial stake in encouraging employers to cover certain brand-name drugs rather than others, according to Towers Perrin, Stamford, Conn.

The benchmark formulary does not take rebates or other discounts into effect, and it does include brand-name products that are especially useful, Towers Perrin says.

Towers Perrin developed the reference formulary system by drawing on data from the Towers Perrin Rx Collaborative, an employer drug purchasing coalition it has established.