Investigating the association between prior history of asthma and later diagnosis of COPD: an analysis of British Columbia administrative health database in Canada

Asamoah-Boaheng, Michael (2022) Investigating the association between prior history of asthma and later diagnosis of COPD: an analysis of British Columbia administrative health database in Canada. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Adult asthma patients are at an increased likelihood of being diagnosed with chronic obstructive pulmonary diseases (COPD) later in life. The main aim of this dissertation is to examine the factors associated with asthma patients that lead to COPD diagnosis later in life. The study was motivated by the dearth of research explaining the complex relationship between prior history of asthma and a later diagnosis of COPD. Similarly, there is a lack of academic literature and clinical research that examines the association between sub-optimal medication adherence (MA) in asthma patients and their subsequent risk of COPD. Additionally, there exists no gold standard with a clinical or pharmacological rationale for measuring optimal MA in asthma patients using pharmacy-based databases. In examining these critical research areas, meta-analysis and a retrospective observational cohort design were employed. Four linked databases obtained from the Population Data BC, spanning from January 1, 1998, to December 31, 2018, were used for data analysis. The meta-analysis showed that patients with a previous history of asthma were 7.87 times more likely to develop COPD in the future than were non-asthmatics. In addition, an analysis of the Population Data BC found that the following risk factors predicted COPD in asthma patients: “being an older adult (40 years and older)”, “being male and obese”, “a history of tobacco use”, “comorbidity burden”, “length of hospital stay”, “asthma severity levels”, “asthma exacerbations”, and overuse of Short-Acting Beta-2 Agonist (SABA). Also, the study identified medication possession ratio (MPR) and proportion of days covered (PDC) as the most commonly used methods for measuring medication adherence with higher sensitivity. The study identified an adherence threshold of at least 0.80 as optimal in categorizing adherent and non-adherent adult asthma patients. Further, patients who achieved a sub-optimal level of MA were at a significantly increased risk for developing COPD over time after adjusting for relevant confounders. Levels of asthma severity modified the MA effect. Additionally, overuse of short-acting beta-2 agonist (SABA) was significantly associated with an increased risk of COPD after adjusting for relevant confounders and covariates. This study’s findings provide important insights into the lifestyle and behavioural risk factors associated with COPD risk. Healthcare providers and policymakers should highlight the need for smoking cessation programs, weight management, and medication compliance interventions, particularly in difficult-to-control adult asthma patients who are at an elevated risk of developing COPD.

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