Factors affecting the trajectory of health-related quality of life in COPD patients

BACKGROUND: Health-related quality of life (HR-QoL) is an important issue in patients with chronic obstructive pulmonary disease (COPD), as in other chronic illness groups. However, there is limited information on longitudinal changes in HR-QoL over time with the illness trajectory model. OBJECTIVE: To identify different patterns of HR-QoL changes in longitudinal data, and reveal potential predictors affecting these trajectories. METHODS: Subjects with COPD (n = 249) were drawn from the Korean Obstructive Lung Disease cohort, which was conducted from 2005 to 2012. Longitudinal data were drawn from the St George's Respiratory Questionnaire and clinical measures. Growth mixture modelling was used to estimate distinct patterns, and binary and ordinal logistic regression were used to determine factors affecting different trajectory HR-QoL patterns using STATA 12.0. RESULTS: Five distinct HR-QoL patterns were identified. Results show that the level of baseline HR-QoL was significantly associated with age, the BODE (Body mass index, airflow Obstruction, Dyspnea, and Exercise capacity) index at baseline, sleep disturbance, experience of exacerbation in previous year and level of depression. Distinct patterns in HR-QoL that improved vs. worsened were significantly associated with BODE index, number of respiratory symptoms and depression level. CONCLUSIONS: These findings suggest that comprehensive assessment and individualised management programmes are needed to improve HR-QoL in COPD patients.