State Medicaid programs could lower costs by consulting the World Health Organization’s concept of “essential medicines” when determining which drugs to offer beneficiaries, a new study finds.

Researchers at the University of California, San Francisco, compared the WHO’s Essential Medicine List from 2009 against the Medicaid Preferred Drug Lists from 40 states. The investigators said that revisions of the WHO list are reviewed rigorously on a biannual basis, the Bureau of National Affairs reported.

The investigators found that — when looking at a subset of drugs — a majority of 120 WHO list drugs were on at least 50% of the state lists. However, medications that showed up on state lists were less likely than those on the WHO list to have generic versions or to be first-line treatments, according to the study. Additionally, medications varied greatly across state lists.

According to the study’s authors, if states used the World Health Organization Essential Medicines List as a starting point, it might lower the number of medicines available to Medicaid beneficiaries. On the other hand, patients could have more confidence that the drugs they take would be effective and safe, BNA reported. The study is slated for publication in the American Journal of Public Health.