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UBC Theses and Dissertations

A population-based cohort study evaluating the association between inhaled corticosteroid use and statin use with lung cancer risk in chronic obstructive pulmonary disease patients Raymakers, Adam John Nelson


Background: Lung cancer incidence is elevated in patients with chronic obstructive pulmonary disease (COPD), often due to smoking, but potentially also resulting from inflammation. COPD patients are also often diagnosed with comorbidities, the most prominent being cardiovascular disease (CVD). Statins, due to the increased prevalence of CVD, and inhaled corticosteroids (ICS), are two commonly prescribed medications for COPD patients that may reduce lung cancer risk. Objective: To evaluate the association between lung cancer risk with ICS and statin use in COPD patients. A priori, the hypothesis of this study was that use of these medications would be associated with a reduction in lung cancer risk. Methods: This study used population-based data for the province of British Columbia to identify a cohort COPD patients. To be included, patients were to have filled three prescriptions for COPD-related medications within a twelve-month period. To evaluate the association between statin and ICS use with lung cancer risk, an array of methods of defining medication exposure were used, including a novel recency-weighed approach. Results: In the analysis evaluating the association between ICS use and lung cancer diagnosis, time-dependent ICS exposure was associated with a 30% reduction in lung cancer risk. The recency-weighted duration of use exposure metric also demonstrated a protective effect from ICS exposure (HR: 0.74 (95% CI: 0.66-0.82). This protective effect was consistent over all exposure metrics. Evaluation of the association between statin use and lung cancer risk produced less consistent results. However, the best-fitting model which incorporated the recency-weighted duration of use exposure metric indicated a protective effect from statin exposure (HR: 0.85 (95% CI: 0.77-0.93). Statin exposure in patients 65 or over was protective against lung cancer diagnosis consistently for all exposure metrics. An interaction term between ICS and statin use was also explored, but was not found to be statistically significant. Conclusions: These results suggest that the benefits of ICS and statin use might extend beyond their primary indication. The results also underscore the importance of using appropriate methods for measuring medication exposure in observational studies, particularly those using administrative data. Finally, this work highlights the importance of ‘real-world’ evidence.

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