|dc.description.abstract||Background & objective: Adults with cystic fibrosis (CF) were assessed to establish whether a relationship exists between inflammation (systemic and/or pulmonary), physical activity and/or exercise tolerance, following in-hospital treatment for an acute exacerbation, and whether these factors can predict for time to next pulmonary exacerbation. In addition to this, demographic information was collected to establish if age, sex, lung function, and/or body mass index is related to the primary study outcomes.
Methods: Adults with CF were included following hospitalisation for a pulmonary exacerbation and were followed up for 12 months. Inflammatory markers were measured immediately post discharge via sputum and plasma concentrations of interleukin-6, interleukin-8 and tumour necrosis factor-α. Physical activity was monitored for 7 days post discharge via a Sensewear armband. Exercise tolerance was measured at this same time point via six-minute walk test (6MWT), modified shuttle test-25 (MST-25) and isometric quadriceps strength. Statistical analyses included Shapiro-Wilk’s test and Q-Q plots to determine normal distribution, Ttests, Pearson’s correlational analyses and one-way MANOVAs.
Results: Thirty-two adults with CF (18 (56%) male, aged 28.8 ± 8.8 years, FEV1 59.4 ± 23.0% predicted) were prospectively recruited via a sample of convenience. Physical activity negatively correlated with plasma inflammation (r = -0.48, p < 0.01), and positively with disease severity via FEV1 (r = 0.45, p < 0.05) and body mass index (r = 0.39, p < 0.05). Body mass index also negatively correlated with sputum inflammation (r = -0.51; p > 0.01). No associations were found between plasma cytokines and measures of exercise tolerance (six minute walk distance (6MWD), MST-25, quadriceps strength). 6MWD and MST-25 had low and moderate positive correlations respectively with disease severity in both FEV1 (r = 0.48, p = 0.005; r = 0.79, p < 0.001) and FEV1 % predicted (r = 0.43, p < 0.05; r = 0.66, p < 0.001). Male participants had significantly greater quadriceps strength than females (t (30) = 3.779, p = 0.001). Quadriceps strength did not correlate with either 6MWD (r = 0.22, p > 0.1) or MST-25 (r = 0.35, p > 0.01). There was no significant relationship between time to reexacerbation and any inflammatory marker, or any measure of physical activity or exercise tolerance (all p > 0.05).
Conclusion: Increased physical activity levels following exacerbation in adults with CF is associated with lower levels of systemic inflammation, however, is unrelated to pulmonary inflammation. Both systemic and pulmonary inflammation are unrelated to measures of exercise tolerance (aerobic nor strength related). Time to next pulmonary exacerbation is not related to postdischarge inflammation, physical activity levels or exercise tolerance. MST-25 was found to be a stronger predictor of FEV1 compared to 6MWD. No associations were found between sex and physical activity and/or aerobic exercise tolerance.||