Pulmonary function, functional capacity, body composition and quality of life in adult patients with cystic fibrosis

Abstract

Introduction: Cystic fibrosis (CF) is a hereditary, autosomal recessive multisystem disease characterized by chronic obstructive pulmonary disease, pancreatic insufficiency, malnutrition and high levels of electrolytes in sweat. The progression of lung disease associated with malnutrition result in reduced physical capacity. Thus, the functional assessment helps to understand the impact of the disease on exercise capacity. Moreover, since few studies have assessed the association between lung function, nutritional status and functional capacity the causes of exercise limitation in these patients are still not clear. Objective: The main objective of this study was to characterize the functionality and quality of life of adult patients with cystic fibrosis. Secondarily, we aimed at evaluate the association between pulmonary function, functional capacity variables and quality of life. Methods: This was a cross-sectional study with 21 patients with CF, with a mean age of 25.5 ± 6 years. The subjects underwent the following tests: lung function (spirometry, whole body plethysmography, measurement of diffusing capacity for carbon monoxide and respiratory muscle strength), 6-minute walk distance test (6MWT), cardiopulmonary exercise testing (CPET), nutritional status and peripheral muscle evaluation (a control group with 21 healthy subjects was also included for this measure) . All patients answered a specific CF quality of life questionnaire (Cystic Fibrosis Questionnaire-Revised - CFQ-R). Results: The patients showed reduced values for fat-free mass (75.8±11,5%) and lower than predict for VO2 peak (78±30 %), 6MWT distance (80,8±13,3 %), and respiratory muscle strength (Maximal inspiratory pressure = 62,6± 25,6%; Maximal expiratory pressure = 69,5± 32,7%). When compared to control, quadriceps strength (P<0.001) and endurance (P=0.03) also showed reduced values. Only five patients classified as severe (FEV1 <40%) had ventilatory limitation in CPET. There was association between pulmonary function variables and the results of the exercise tests (CPET and 6MWT), as well as between lung hyperinflation and CPET variables, and between peripheral muscles function variables (strength and endurance) and the 6MWT. The quality of life was impaired, but without association with the functional variables. Conclusion: Adult patients with CF have impaired quality of life, reduced exercise tolerance and diminished peripheral muscle strength and endurance. Although pulmonary function influences the exercise capacity, skeletal muscle performance might be the limiting factor for maximal exercise in patients with mild-to-moderate lung disease.