UBC Theses and Dissertations
Utilization and safety studies of inhaled pharmacotherapies in COPD Bahremand, Taraneh
Chronic Obstructive Pulmonary Disease (COPD) is a common chronic disease of the airways responsible for significant burden to the patient and health-care systems. Pharmacotherapy is a cornerstone of COPD management. We aimed at evaluating population-level trends of filled inhaled prescriptions over the time course of COPD and their agreement with guidelines. Further, inhaled medications have potential side effects that are not sufficiently investigated. We aimed to examine the association between use of long-acting or short-acting muscarinic antagonists (LAMA and SAMA) and the risk of acute angle-closure glaucoma (AACG) in COPD. We used administrative health databases in British Columbia, Canada to create a cohort of COPD patients. We quantified inhaled medication prescriptions within each year of follow-up, and documented their trends over the time course of COPD. Using generalized linear models, we investigated the association between the frequent exacerbator status and filling a prescription after a physician visit. To assess AACG risk, a case-control study was nested within this cohort. All cases of AACG followed by laser iridotomy were obtained and matched to controls by age, sex, and calendar time. The exposure to LAMA/SAMA was categorized into three levels: current use (≥ 1 prescription of LAMA or SAMA during the last 30 days), new use (initiated medication in the last 30 days), and past use (≥ 1 prescription in 6 months to 30 days before AACG). Conditional logistic regression models were used to estimate the rate ratio (RR) of AACG controlling for confounders. The most common medication class in COPD incident cohort during the first year of diagnosis was inhaled corticosteroids (ICS, used by 49.9%). We documented low utilization of monotherapies (specifically LAMA) and high utilization of combination therapies (particularly containing ICS). Moreover, specialists were less likely to consider exacerbation history in the choice of therapies compared with general practitioners. In the safety study, 92 cases were matched to 460 controls. We demonstrated that the use of inhaled muscarinic antagonists in a COPD population, regardless of dose and timing, does not appear to affect the risk of AACG (adjusted RR:1.14, 95%CI [0.64 to 2.01], p=0.65). Results remained consistent in sensitivity analyses.
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