RATIONALE
Individuals with Chronic Obstructive Pulmonary Disease (COPD) have a high prevalence of depression, which is associated with increased COPD hospitalizations and readmissions.
OBJECTIVES
Examine the impact of depressive symptoms compared to FEV1% on COPD morbidity.
METHODS
Using longitudinal data from individuals with COPD in the Subpopulations and Intermediate Outcome Measures in COPD Study, longitudinal growth analysis was performed to assess COPD morbidity by assessing differences in baseline 6 minute walk distance (6MWD) and patient reported outcomes (PROs) and their rate of change over time explained by depressive symptoms or lung function, as measured by Hospital Anxiety and Depression Scale (HADS) or FEV1% respectively. PROs consisted of in person completion of St. George's Respiratory Questionnaire (SGRQ), COPD Assessment Test (CAT), Functional Assessment of Chronic Illness Therapy Fatigue (FACIT-F), and Modified Medical Research Council Dyspnea Scale (mMRC) measures.
RESULTS
Of individuals analyzed (n=1830), 43% were females, 81% Caucasian with mean ±SD age of 65.1±8.1, and 52.7±27.5 pack-years smoking. Mean ±SD FEV1% was 60.9±23.0% and 20% had clinically significant depressive symptoms. Adjusted models showed higher HADS scores and lower FEV1% each were associated with worse PROs at baseline (p≤0.001). Depression accounted for more baseline variance in SGRQ, CAT, and FACT-F than FEV1%, explaining 30-67% of heterogeneity. While FEV1% accounted for more baseline variance in mMRC and 6MWD than depression, explaining 16-32% of heterogeneity. Depressive symptoms accounted for 3-17% variance in change over time in PROs. In contrast, FEV1% accounted for 1-4% variance over time in PROs.
CONCLUSIONS
Depression is more strongly associated with many PROs at baseline and their change over time compared to FEV1%. Recognizing and incorporating the impact of depressive symptoms into individualized care may improve COPD outcomes.