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UBC Theses and Dissertations

Evaluating strategies for the early detection of chronic obstructive pulmonary disease Johnson, Kate


Background: Chronic obstructive pulmonary disease (COPD) is a highly prevalent disease that often goes undiagnosed. Reducing the burden of undiagnosed COPD requires well designed early detection programs that have been formally evaluated. Objectives: The objective of this thesis was to determine whether there are subgroups of COPD patients in which case detection, followed by evidence-based disease management, would be cost-effective compared with the status quo (no case detection). To answer this question, I 1) identified factors that distinguish patients with undiagnosed from those with diagnosed COPD, 2) assessed heterogeneity in the presence of respiratory symptoms, 3) analysed healthcare encounters prior to COPD diagnosis to identify opportunities for case detection, and 4) evaluated the cost-effectiveness of early detection strategies. Methods: I performed a systematic review to generate pooled odds ratios for factors associated with a COPD diagnosis. I used data from a population-based Canadian study to assess heterogeneity between individuals in the occurrence of respiratory symptoms. I characterised healthcare encounters before COPD diagnosis using health administrative data from British Columbia. I combined evidence from Objectives 1-3 in a whole disease model of COPD to assess the cost-effectiveness of case detection strategies implemented during routine primary care visits. Results: Patients with diagnosed COPD were less likely to have mild disease (OR 0.30, 95%CI 0.24–0.37) and more likely to report respiratory symptoms (OR 11.45 95%CI 7.20–18.21) than patients with undiagnosed COPD. However, individual-specific probabilities for the occurrence of symptoms indicated substantial heterogeneity between patients. COPD patients frequently visited primary care physicians before diagnosis (mean 10.29, IQR 4–13 visits/year). In the two years prior to diagnosis, 72.1% of COPD patients had a respiratory-related primary care visit that did not result in a diagnosis. In the preferred case detection strategy, all patients ≥40 years received a screening questionnaire during their routine visits to a primary care physician. This strategy had an Incremental Cost-Effectiveness Ratio of $18,791/QALY compared to no case detection. Conclusions: Patients with undiagnosed COPD have identifiable characteristics, they frequently encounter the healthcare system, and strategies for improving their early detection are cost-effective when combined with guideline-recommended treatment.

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