Functional impairment in people with interstitial lung diseases: is one measure enough?

Abstract

Introduction: Interstitial lung diseases (ILD) comprehend a large group of lung diseases that include disease settings associated with sustained progression and leading to respiratory failure, decreased functional status and premature death. Functional status can be defined as an individual’s ability to perform normal daily activities required to meet basic needs, fulfill usual roles and maintain health and well-being. It includes functional capacity, i.e., an individual’s maximum capacity to perform daily life activities in a standardized environment; and functional performance, i.e., the activities people actually do during the course of their daily life. Decreased functional status is the most frequent reported impact by people with ILD and is associated with increased dependence on others, exacerbations and hospital admissions. Yet, little is known how functional status is impaired in people with ILD. Objectives: To explore functional impairments in people with ILD. Methods: A cross-sectional study was conducted with people with ILD. Age, sex, body mass index (BMI) and lung function were collected. Functional capacity was assessed with the 1-minute sit-tostand test (1-minSTS), the 6-minute walk test (6MWT) and quadriceps maximum voluntary contraction (QMVC). Functional performance was assessed with the London Chest Activities of Daily Living (LCADL). Participants’ functional capacity was classified as impaired if the 1-minSTS, 6MWT and/or QMVC values were below 70% of predicted. Participants’ functional performance was considered impaired if above the cut-off point of 28% of the LCADL. Descriptive statistics were performed. Results: In total, 156 people with ILD (65 ± 13 years; 51.9% female; BMI 28.7 ± 6.1 kg/m2 ; FVC 79.2 ± 20.1%predicted; DLCO 55.4 ± 21.2%predicted) participated. ILD diagnosis included fibrosis hypersensitivity pneumonitis (43%), idiopathic pulmonary fibrosis (24%), connective tissue disease-associated ILD (14%), dust-related (1%) and others (17%). Functional capacity was impaired in 55.3%, 23.8% and 41.8% of the sample assessed with the 1-minSTS, 6MWT and QMVC, respectively. Functional performance was impaired in 48.5% of people with ILD. Conclusions: A large proportion of people with ILD show impairments in functional status, i.e., in capacity, in performance or in both. Lack of impairment in one measure does not rule out functional status impairment. Patient-centered and comprehensive assessment of functional status seems vital to guide individually tailored interventions and improve this meaningful domain for the daily life of ILD patients.