Addition of Generic Medication Vouchers to a Pharmacist Academic Detailing Program: Effects on the Generic Dispensing Ratio in a Physician-Hospital Organization

BACKGROUND: Generic dispensing ratio (GDR) is an important measure of efficiency in pharmacy benefit management. A few studies have examined the effects of academic detailing or generic drug samples on GDR. On July 1, 2007, a physician-hospital organization (PHO) with a pay-for-performance incentive for generic utilization initiated a pilot generic medication voucher program that augmented its existing pharmacist-led academic detailing efforts. No published studies have examined the role of generic medication vouchers in promoting generic drug utilization. OBJECTIVES: To determine if supplementing an existing academic detailing initiative in a PHO with a generic medication voucher program would be more effective in increasing the GDR compared with academic detailing alone. METHODS: The intervention took place over the 9-month period from July 1, 2007, through March 31, 2008. Vouchers provided patients with the first fill of a 30-day supply of a generic drug at no cost to the patient for 8 specific generic medications obtained through a national community pharmacy chain. The study was conducted in a PHO composed of 7 hospitals and approximately 2,900 physicians (900 primary care providers [PCPs] and 2,000 specialists). Of the approximately 300 PCP practices, 21 practices with at least 2 physicians each were selected on the basis of high prescription volume (more than 500 pharmacy claims for the practice over a 12-month pre-baseline period) and low GDR (practice GDR less than 55% in the 12-month pre-baseline period). These 21 practices were then randomized to a control group of academic detailing alone or the intervention group that received academic detailing plus generic medication vouchers. One of 10 intervention groups declined to participate, and 2 of 11 control groups dropped out of the PHO. GDR was calculated monthly for all pharmacy claims including the 8 voucher medications. GDR was defined as the ratio of the total number of paid generic pharmacy claims divided by the total number of paid pharmacy claims for 108 prescriber identification numbers (Drug Enforcement Administration [DEA] or National Provider Identifier [NPI]) for 9 intervention groups [n = 53 PCPs] and 9 control groups [n = 55 PCPs]). For both intervention and control arms, the GDR for each month from July 2007 (start of 2007 Q3, intervention start date) through September 2008 (end of 2008 Q3, 6 months after intervention end date) was compared with the same month in the previous year. A descriptive analysis compared a 9-month baseline period from 2006 Q3 through 2007 Q1 with a 9-month voucher period from 2007 Q3 to 2008 Q1. A panel data regression analysis assessed GDR for 18 practices over 27 months (12 months pre-intervention and 15 months post-intervention). RESULTS: A total of 656 vouchers were redeemed over the 9-month voucher period from July 1, 2007, through March 31, 2008, for an average of about 12 vouchers per participating physician; approximately one-third of the redeemed vouchers were for generic simvastatin. The GDR increase for all drugs, including the 8 voucher drugs, was 7.4 points for the 9 PCP group practices with access to generic medication vouchers, from 53.4% in the 9-month baseline period to 60.8% in the 9-month voucher period, compared with a 6.2 point increase for the control group from 55.9% during baseline to 62.1% during the voucher period. The panel data regression model estimated that the medication voucher program was associated with a 1.77-point increase in overall GDR compared with academic detailing alone (P = 0.047). CONCLUSIONS: Compared with academic detailing alone, a generic medication voucher program providing a 30-day supply of 8 specific medications in addition to academic detailing in PCP groups with low GDR and high prescribing volume in an outpatient setting was associated with a small but statistically significant increase in adjusted overall GDR.