Objectives: Previous studies reported that environmental factors, particularly the work environment, were related to quality of life (QoL) in patients with asthma. However, the pathway that links workplace and QoL in adults with asthma is still not clear. The aim of this study was to explore the comprehensive environmental factors, asthma control, and QoL pathways in patients with asthma.
Study design and setting: Two cohorts of patients with asthma were established, including a prospective phase cohort in 2006 and a cross-sectional phase cohort in 2012. The Asthma Control Test was used to determine the level of disease control, and QoL was assessed by using the Taiwanese version of an asthma quality-of-life questionnaire. In 2014, a structural equation model was applied to explore the pathways from the risk factors to QoL.
Results: The structural equation model for predicting QoL provided a good fit (χ(2) [degrees of freedom] = 43.81 [38]; root mean square error of approximation 0.021 [90% confidence interval, 0.001-0.044]) after combining the two cohorts. The wheeze frequency, allergic response frequency, parental asthma, and asthma control were directly associated with QoL. We found that patients who were obese and who worked in poor environments had increased work symptoms and wheeze frequency during the previous year in a cross-sectional phase cohort. However, we did not find that body mass index was a significant factor in a prospective cohort. The patients with obesity and with frequent work symptoms, which induced poor asthma control, were possible mechanisms in the pathway from workplace exposure to poor QoL in the observed adults with asthma in our combined data.
Conclusion: Body mass index, the work environment, and the wheeze frequency should be considered when assessing asthma control and QoL in adult patients with asthma. Patients who reduce their body weight or avoid exposure to poor workplaces may find this useful for their asthma control and improvement of their QoL.