Effects of the Association of L-arginine and Liposomal Vitamin C on Fatigue in COPD Patients With Chronic Respiratory Failure After Rehabilitation Intervention

The primary objective of this project is to assess the effects of L-arginine plus Vitamin C supplementation on the physical outcomes in a group of COPD patients with chronic respiratory failure who underwent a 28-day PR program.

Eligible participants will be randomized using a random number generator in a 1:1 ratio to receive a twice-daily oral supplementation with either a combination of 1.66 g l-arginine plus 500 mg liposomal vitamin C (Bioarginina® C, Farmaceutici Damor, Naples, Italy) or a placebo for 28 days. Vials containing the active supplement or the placebo will be supplied by Farmaceutici Damor and will be made indistinguishable in appearance. All patients will undergo an intensive multidisciplinary PR program based on endurance and strength training. The main outcome of the study is the fatigue severity scale (FSS) total score after rehabilitation. Secondary outcomes include: 6-minute walking distance, forced expiratory volume in the first second (FEV1), COPD assessment test (CAT) score, endothelial function assessed through flow-mediated dilation (FMD), and muscular strength assessed through handgrip measurement.

Anthropometric, clinical, and functional characteristics of the study participants will be reported as mean ± standard deviation (SD) or median (interquartile range, IQR) for continuous variables and as absolute values (percentages) for categorical variables. Changes from baseline for continuous variables will be expressed as deltas (values at 28 days minus the values at baseline), and differences between the interventional groups will be evaluated using the Student's t-test for normally distributed variables or the Mann-Whitney U test for skewed variables.