Life-Space mobility and clinical outcomes in COPD

Abstract

Background: Social isolation is a common experience in patients with COPD but is not captured by existing patient-reported outcomes, and its association with clinical outcomes is unknown.

Methods: We prospectively enrolled adults with stable COPD who completed the University of Alabama at Birmingham Life Space Assessment (LSA) (range: 0-120, restricted Life-Space mobility: ≤60 and a marker of social isolation in older adults); six-minute walk test (6MWT), and the University of California at San Diego Shortness of Breath Questionnaire, COPD Assessment Test, and Hospital Anxiety and Depression Scale. The occurrence of severe exacerbations (emergency room visit or hospitalization) was recorded by review of the electronic record up to 1 year after enrollment. We determined associations between Life-Space mobility and clinical outcomes using regression analyses.

Results: Fifty subjects had a mean ± SD %-predicted FEV₁ of 42.9±15.5, and 23 (46%) had restricted Life-Space mobility. After adjusting for age, gender, %-predicted FEV₁, comorbidity count, inhaled corticosteroid/long-acting beta₂-agonist use, and prior cardiopulmonary rehabilitation, subjects with restricted Life-Space had an increased risk for severe exacerbations (adjusted incidence rate ratio 4.65, 95% CI 1.19-18.23, P=0.03). LSA scores were associated with 6MWD (R=0.50, P<0.001), dyspnea (R=-0.58, P<0.001), quality of life (R=-0.34, P=0.02), and depressive symptoms (R=-0.39, P=0.005).

Conclusion: Restricted Life-Space mobility predicts severe exacerbations and is associated with reduced exercise tolerance, more severe dyspnea, reduced quality of life, and greater depressive symptoms.

Keywords: COPD; acute exacerbation of COPD; patient-reported outcomes.

Figure 1

The UAB LSA. Notes: The UAB LSA measures Life-Space mobility in the 4 weeks prior to administration through five Life-Space levels from the bedroom where one sleeps to beyond the town. The UAB LSA has no copyright. No permission is required to reproduce the form, and the authors encourage its use in research and clinical settings. Values for distance, frequency, and independence of movement are multiplied to generate a score for each Life-Space level, and these scores are summed to generate a total LSA score. Mobility through a higher Life-Space level automatically means someone moved through lower Life-Space levels, ie, if someone moves through the town, he also travels through the house and the neighborhood. In such a situation, the scores for the lower Life-Space level must be corrected to match those of the immediately higher Life-Space level. Abbreviations: UAB, University of Alabama at Birmingham; LSA, Life Space Assessment.

Figure 2

Life-Space mobility and clinical outcomes in COPD. Note: Linear regression analyses between continuous LSA score and distance on 6MWT, SOBQ, CAT, and HADS–Depression. Abbreviations: LSA, Life Space Assessment; 6MWT, Six-minute walk test; SOBQ, University of California at San Diego Shortness of Breath Questionnaire; CAT, COPD Assessment Test; HADS, Hospital Anxiety and Depression Scale.