Evaluation of factors related to prescription drug expenditures, prescribing trends and physican visits: the role of direct-to-consumer advertising expenditures, demographics, and health insurance coverage
Abstract
This study evaluated the relationships of age, gender, health insurance coverage,
and DTCA expenditures, with physician visits for symptoms and/or conditions treated
with the five advertised drug classes (allergy medications, antilipemics, gastrointestinals,
antidepressants, antihypertensives) selected, number of prescriptions written and
expenditures for the selected advertised drugs from January 1994 to April 2001. The
study also evaluated the relationships of physician visits with number of prescriptions
written and expenditures for drugs from the five drug classes. All relationships were
compared prior to and following the relaxation of the broadcast advertising guidelines:
(a) January 1994 to August 1997; and (b) September 1997 to April 2001.
The data for the study were obtained from the following: (a) CMR for DTCA
expenditures; (b) NAMCS for age, gender, health insurance coverage, physician visits,
and prescriptions written; and (c) AWP and Novartis Pharmacy Benefit reports to
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estimate prices of the drugs. Time series analysis was used to determine the relationships
with the dependent variable physician visits. Mixed model analysis was used to evaluate
the relationships with prescriptions written and expenditures. To compare the
relationships, the datasets were split by time period and reanalyzed with time series or
mixed model analysis as appropriate.
Age had a negative relationship with the prescriptions written and expenditures
for gastrointestinals while older individuals had a positive relationship with the
prescriptions written and expenditures for antidepressants. Gender (women) was
positively related to prescriptions written and expenditures for allergy medications and
gastrointestinals. Health insurance coverage had a negative relationship with allergyrelated
visits and prescriptions written and expenditures for antihypertensives. However,
health insurance coverage was positively related to prescriptions written for
antidepressants.
DTCA expenditures were positively related to the number of patients diagnosed
with hyperlipidemia and the prescriptions written and expenditures for allergy
medications, antilipemics, and gastrointestinals. DTCA expenditures were negatively
related to the prescriptions written and expenditures for antihypertensives. Only
physician visits were consistently related to prescriptions written and expenditures for all
drug classes for the entire time period and both time periods. The study results indicate
that different factors are related to physician visits, prescriptions written and their
expenditures for the different drug classes.
Department
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