Pgi13: Factors Associated With Physician Knowledge of Whether Prescription Drugs Are on Formulary

Abstract

OBJECTIVE: Prescription drug formularies have been used by many pharmacy benefit managers (PBMs) as a tool to control the rising costs of prescription drugs and became increasingly popular since the 1990s. Despite its popularity, little is known about how familiar physicians are with what prescriptions are on formulary. This study examines factors associated with physician knowledge of formulary. METHODS: The National Ambulatory Medical Care Survey (NAMCS) is a data series of annual survey of a national representative sample of physician office visits. It provides up to six medications associated with each office visit. The 1998 NAMCS collected information regarding the formulary status (yes, no, do not know, or not applicable) of each medication and provided a unique opportunities to assess physicians' knowledge of formulary. Univariate analyses as well as multivariate logit model were used to examine the association between physician knowledge of formulary and types of visits, physician specialty and practice locations. RESULTS: On average, 47% of physicians did not know whether the drug they prescribed was on formulary. Physicians whose patients belonged to an HMO and were paid by capitation were seven times more likely to know whether a drug was on formulary, compared to those whose patients were neither in an HMO nor capitated. Physicians in the South were 1.7 times more likely to know than those in the West, whereas the odd‐ratios was 0.7 for those in the Midwest. Neither physician specialty (primary care physician versus specialist) nor patient history (new versus established patient) was found to be significantly associated with physician knowledge of formulary. CONCLUSIONS: It is important for PBMs to find mechanisms to increase physician awareness of whether a patient's medications are on formulary. Improving physicians' understanding of what medications were on formulary could potentially decrease prescription drug costs for health care plans and patients.