Relationship between functional capacity and perceived limitations in activities of daily living in individuals with interstitial lung disease

Background: Dyspnea during physical activities and reduced functional capacity are common in individuals with interstitial lung disease (ILD). Understanding this relationship is important for characterizing this population. Aim: To investigate whether functional capacity and exertional dyspnea are related to and can predict dyspnea-related limitations in activities of daily living (ADLs) in individuals with ILD. Methods: This cross-sectional study included 62 individuals with ILD (38 women), aged 60 ± 11 years, with a forced vital capacity of 68.2 ± 21.3% predicted. Pulmonary function was assessed by body plethysmography, functional capacity by the Six-Minute Walk Test (6MWT), exertional dyspnea by the Modified Borg Scale, and ADL limitation by the London Chest Activity of Daily Living (LCADL) scale. Correlation and simple linear regression analyses were performed, considering 6MWT performance and exertional dyspnea as independent variables. Results: The LCADL total score correlated with 6MWT distance (r=−0.45), 6MWT distance (% predicted) (r=−0.43), and exertional dyspnea (r=0.51). The LCADL total percentage score correlated with 6MWT distance (r=−0.49), 6MWT distance (% predicted) (r=−0.48), and exertional dyspnea (r=0.56) (p<0.05 for all). In the regression analyses, the LCADL total score was explained by 6MWT distance (R2=0.23), 6MWT distance (% predicted) (R2=0.22), and exertional dyspnea (R2=0.28). The LCADL total percentage score was explained by 6MWT distance (R2=0.38), 6MWT distance (%predicted) (R2=0.39), and exertional dyspnea (R2=0.25) (p<0.001). Conclusion: Poorer functional performance and greater perceived exertional dyspnea were associated with greater ADL limitations and were able to predict the variability in LCADL scores.