Functional and psychological variables both affect daily physical activity in COPD: a structural equations model
Wytske A Altenburg, Linda Bossenbroek, Mathieu H G de Greef, Huib A M Kerstjens, Nick H T ten Hacken, Johan B Wempe, Wytske A Altenburg, Linda Bossenbroek, Mathieu H G de Greef, Huib A M Kerstjens, Nick H T ten Hacken, Johan B Wempe
Abstract
Background: Daily physical activity (DPA) level is reduced in patients with COPD. The aim of this study was to investigate the association of DPA with functional and psychological variables in these patients.
Methods: 155 COPD patients (102 males, median (IQR) age 62 years (54-69 years), predicted FEV1 60% (40-75%) were included. We assessed DPA (DigiWalker SW-200), functional capacity and psychological factors.
Results: DPA level was significantly associated with all functional capacity variables and two psychological variables (Perceived Physical Ability Subscale, depression subscale of the Hospital Anxiety and Depression Scale). The six-minute walking distance and St. George Respiratory Questionnaire activity score explained 37% of the variance of DPA in a regression analysis. A structural equations model revealed that psychological variables indirectly explained DPA through functional capacity variables. DPA was stronger associated with functional capacity variables and weaker with psychological variables in patients with lower functional status than in patients with higher functional status.
Conclusions: Higher levels of DPA are associated with better functional capacity, but interestingly, DPA is also affected by psychological factors, though only indirectly, via functional capacity. The effect of specific treatment addressing psychological factors on DPA level and exercise tolerance needs further investigation.
Clinical trial registration: ClinicalTrials.gov, NCT00614796.
Keywords: 6MWD; CCQ; COPD; Clinical COPD Questionnaire; DEFS; DPA; Dutch Exertion and Fatigue Scale; FEV(1); Forced Expiration Volume in one second; Functional capacity; GARS; GOLD; Groningen Activity and Restriction Scale; HADS; Hospital Anxiety and Depression Scale; IQR; PPAS; PR; Perceived Physical Ability Subscale; Physical activity; Psychological capacity; RMSEA; RV%TLC; SEM; SF-36; SGRQ; SPSS; SRQ-E; Scientific Package of Social Sciences; Self-Regulation Questionnaire for Exercise; Short Form 36; St. George Respiratory Questionnaire; Structural equations model; VO(2)peak; chronic obstructive pulmonary disease; daily physical activity; global initiative for chronic obstructive lung disease; interquartile range; peak oxygen uptake; pulmonary rehabilitation; residual volume as percentage of total lung capacity; root mean square error of approximation; six-minute walking distance; structural equations modeling.
Copyright © 2013 Elsevier Ltd. All rights reserved.
Source: PubMed