Predictors of physical activity in patients with idiopathic pulmonary fibrosis

Abstract

Background: Physical activity plays a cardinal role in health status and mortality in patients with chronic respiratory disease. Although recent study has shown that there is a significant reduction in physical activity in patients with idiopathic pulmonary fibrosis (IPF), the relationships between physical activity and clinical parameters have not been clarified. The purpose of this study was to investigate the predictors of physical activity in patients with IPF. Methods: Physical activity (steps per day) was monitored in 74 stable IPF patients (mean age: 68.5±7.7 years, mean %FVC: 80.1±21.8 %) using accelerometer for 1 week. The following clinical parameters were measured: age, body mass index (BMI), lung function, arterial blood gases, baseline dyspnea index (BDI), hospital anxiety and depression scale (HADS), cardiopulmonary exercise test (peak VO 2 , minimum SpO 2 ), peripheral muscle strength and respiratory muscle strength. Correlation analysis and subsequent stepwise multiple regression analysis were carried out to assess the associations between these parameters and physical activity. Results: Physical activity (steps per day) was 5192±3717 steps. Age, FVC, DLCO, PaO 2 , BDI, and peak VO 2 were significantly correlated with physical activity. Multiple regression analysis showed that peak VO 2 , PaO 2 and age were independent predictors of physical activity in IPF patients (standardized β: 0.31, 0.29, -0.23, respectively, r 2 :0.369). Conclusions: PaO 2 , age and exercise capacity were predictors of physical activity in IPF patients.