Chronic infection and inflammation affect exercise capacity in cystic fibrosis

Abstract

Pulmonary function and nutritional status are important determinants of exercise capacity in patients with cystic fibrosis (CF). Studies investigating the effects of determinants, such as genotype or infection and inflammation, are scarce and have never been analysed in a multivariate longitudinal model.A prospective longitudinal cohort study was performed to evaluate whether genotype, chronic inflammation and infection were associated with changes in exercise capacity. Furthermore, we investigated whether exercise capacity can predict clinical outcome.504 exercise tests of 149 adolescents with CF were evaluated. Maximal oxygen uptake corrected for body mass % predicted declined 20% during adolescence, and was associated with immunoglobulin (Ig)G levels and chronic Pseudomonas aeruginosa infection. A lower exercise capacity was associated with a higher mortality, steeper decline in pulmonary function and greater increase in IgG levels.Since a decline in exercise capacity during adolescence was negatively associated with IgG levels and chronic P. aeruginosa infection, these data emphasise the importance of prevention and treatment of chronic inflammation and infections in patients with CF. Furthermore, a lower exercise capacity was associated with a higher mortality rate, steeper decline in pulmonary function and higher increase in IgG levels with increasing age in adolescents with CF. This stresses the value of regular exercise testing for assessing prognosis in adolescents with CF.

Statement on Exercise Testing in Cystic Fibrosis

“…Furthermore, exercise testing employing the Godfrey protocol has prognostic value in CF equal to FEV 1 [7]. Recently, it has also been shown that inflammation and (chronic) Pseudomonas aeruginosa infection are related to aerobic exercise capacity [13]. …”

“…The capacity of the body to perform aerobic exercise and utilize oxygen may be limited in CF for different reasons including impaired lung function [21,38], a poor nutritional status [39]/low muscle power [21], a cardiac dysfunction [40], a high level of inflammation [13] and a low habitual physical activity (= deconditioning [21]). Standardized exercise testing allows discriminating between these causes and may guide targeted interventions.…”

“…Multiple studies have established the link between aerobic exercise capacity and survival in CF [7,8,9,10,11,12,13]. Some evidence suggests that peak oxygen uptake determined during an incremental exercise test may better predict structural lung changes visible on thin-section CT imaging [44] and mortality [7] than FEV 1 or BMI, and that data from exercise testing may even provide information in addition to FEV 1 with respect to future decline in FEV 1 and hospitalizations [42].…”

“…Often, a patient's aerobic exercise capacity is also determined to make training recommendations or to determine the effects of a conditioning program [3,4,5,6]. Furthermore, exercise capacity provides prognostic information for clinical outcome and with respect to mortality [7,8,9,10,11,12,13] and may be useful for the assessment of lung transplant candidates [14,15], even though the evidence for an additional value in this respect is currently limited. Finally, exercise capacity is related to quality of life [16].…”

Impact of <b><i>Pseudomonas aeruginosa</i></b> Infection on Respiratory Muscle Function in Adult Cystic Fibrosis Patients

“…These disturbances may affect the lungs, as well as respiratory mechanics, where the presence of both conditions can contribute to dyspnoea and may ultimately lead to respiratory failure. Furthermore, chronic P. aeruginosa infection and high IgG levels were shown to be associated with a decline in exercise capacity in adolescent patients with CF [5], and a decreased exercise capacity is found in a relevant proportion of patients with CF [6]. Despite the link between P. aeruginosa infection and respiratory disturbances, respiratory mechanics are rarely investigated in CF patients.…”