Physician prescribing behavior and its impact on patient-level outcomes.
OBJECTIVE
Concerns over rising drug costs, pharmaceutical advertising, and potential conflicts of interest have focused attention on physician prescribing behavior. We examine how broadly physicians prescribe within the 10 most prevalent therapeutic classes, the factors affecting their choices, and the impact of their prescribing behavior on patient-level outcomes.


METHODS
Retrospective study from 2005 to 2007 examining prescribers with at least 5 initial prescriptions within a class from 2005 to 2007. Medical and pharmacy claims are linked to prescriber information from 146 different health plans, reflecting 1975 to 8923 unique providers per drug class.


METHODS
Primary outcomes are the number of distinct drugs in a class initially prescribed by a physician over 1- and 3-year periods, medication possession ratio, and out-of-pocket costs.


RESULTS
In 8 of 10 therapeutic classes, the median physician prescribes at least 3 different drugs and fewer than 1 in 6 physicians prescribe only brand drugs. Physicians prescribing only 1 or 2 drugs in a class are more likely to prescribe the most advertised drug. Physicians who prescribe fewer drugs are less likely to see patients with other comorbid conditions and varied formulary designs. Prescribing fewer drugs is associated with lower rates of medication adherence and higher out-ofpocket costs for drugs, but the effects are small and inconsistent across classes.


CONCLUSIONS
Physicians prescribe more broadly than commonly perceived. Though narrow prescribers are more likely to prescribe highly advertised drugs, few physicians prescribe these drugs exclusively. Narrow prescribing has modest effects on medication adherence and out-of-pocket costs in some classes.
Department of Pharmaceutical Economics and Policy, University of Southern California, 3335 S Figueroa, Unit A, Los Angeles, CA 90007, USA. gjoyce@healthpolicy.usc.edu
Geoffrey F
GF
Joyce
Mariana P
MP
Carrera
Dana P
DP
Goldman
Neeraj
N
Sood
D000329:Advertising / Q000941:ethics; D016265:Conflict of Interest; D003657:Decision Making; D004345:Drug Industry / Q000706:statistics & numerical data; D006801:Humans; D007345:Insurance Claim Review; D040541:Marketing; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D016012:Poisson Distribution; D010818:Practice Patterns, Physicians' / Q000941:ethics / Q000706:statistics & numerical data*; D055553:Prescription Drugs; D012189:Retrospective Studies
D055553:Prescription Drugs