New research from Express Scripts provides some important insights into the role of patient characteristics and plan design factors when it comes to getting members to switch to lower-tiered agents after a formulary status change. Of the patient-related factors that affected switching, being female, prior statin switching experience, and member outreach to the pharmacy benefit manager consistently and positively influenced switching. Step therapy, brand preferred/nonpreferred copayment differences, and receipt of a response letter alerting the member to the switch positively influenced switching.

Compared to members with a brand preferred/nonpreferred copayment difference of less than $16, members with copayment differences of $16–$30, $31–$40, and $41 and higher were more likely to switch to a preferred agent (20 percent, 23 percent, and 59 percent of the time, respectively). Ellen Cox, director of research at Express Scripts, says, “There is a basic fundamental — the greater the price differential, the more likely the member will switch. That doesn’t mean that the plan makes the branded product financially burdensome; it could reduce the cost of the generic to create that price differential.”

Source: Cox ER, et al. 2007. Ann Pharmacother.41;1946–1953.