Managed Care - January 2008 - (Page 53) THE FORMULARY FILES Factors that affect formulary switching N ew 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.” Factors that predict switching Mail Retail SWITCH TO A PREFERRED AGENT Odds ratio (95% confidence interval) The odds ratio is a way of comparing whether the probability of a certain event is the same for two groups. An odds ratio of 1 implies that the event is equally likely in both groups. An odds ratio greater than 1 implies that the event is more likely in the first group. An odds ratio less than 1 implies that the event is less likely in the first group. Patient-related Female Switched statins Member outreach None (did not contact Express Scripts) Telephoned and used Web Web use only Telephoned only Plan-related Retail copayment differences ≤$10 (reference) $11–$15 $16–$20 ≥$21 Mail copayment differences ≤$15 (reference) $16–$30 $31–$40 ≥$41 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 Source: Cox ER, et al. 2007. Ann Pharmacother.41;1946–1953. JANUARY 2008 / MANAGED CARE 53
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