Semester

Fall

Date of Graduation

2006

Document Type

Dissertation

Degree Type

PhD

College

School of Medicine

Department

Physiology, Pharmacology & Neuroscience

Committee Chair

Michael J. Smith.

Abstract

COPD is ranked as the fourth leading cause of death with an estimated cost of {dollar}37.2 billion in the U.S. primarily due to exacerbations. Therefore, the Global Initiative for Obstructive Lung Disease (GOLD) committee has identified a need for assessing the effect of drug therapies on outcomes of exacerbations, costs, and mortality. This study used Medicaid data from West Virginia and Kentucky, and involved three phases. Phase I assessed the costs incurred due to COPD, and the additional cost burden imposed by a concomitant diagnosis of asthma. Phase II compared the risk and frequency of exacerbations and COPD-related costs of currently available drug therapies. Phase III assessed the effect of inhaled corticosteroids (ICS) on mortality using two different study designs, and also tested if this effect was mediated by the effect of ICS on severe exacerbations. Results of Phase I showed that recipients with COPD incurred 1.5 times significantly higher healthcare costs than recipients without COPD, primarily due to differences in hospitalization and ER costs. Asthma was found to increase the COPD-related cost of a recipient with COPD by 50%. Results for Phase II showed no differences in reducing exacerbations and total COPD-related costs in a relatively less severe COPD population between recipients treated with the combination product of ipratropium/albuterol versus inhaled long-acting beta-agonists. Phase II also showed that therapy with ICS either alone or in combination with an inhaled long-acting beta-agonist did not reduce the risk of a severe exacerbation or the frequency of moderate exacerbations when compared to therapy with short-acting bronchodilators or with an inhaled long-acting beta-agonist. However, recipients initiated on ICS either alone or in combination with an inhaled long-acting beta-agonist had higher total COPD-related costs driven mainly by higher COPD-related prescription drug costs. In Phase III, recipients initiated on ICS had a 40% reduction in mortality using the case-control design. The cohort design found a relative risk reduction of 48%, and an absolute risk reduction of 1.7% corresponding to a value of 59 for number needed to treat. The effect of ICS on mortality was not mediated by the effect of ICS on severe exacerbations.

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