Nutritional support and functional capacity in chronic obstructive pulmonary disease: A systematic review and meta-analysis

Currently, there is confusion about the value of using nutritional support to treat malnutrition and improve functional outcomes in chronic obstructive pulmonary disease (COPD). This systematic review and meta-analysis of randomized, controlled trials (RCT) aimed to clarify the effectiveness of nutritional support in improving functional outcomes in COPD. A systematic review identified 12 RCT (n=448) in stable COPD patients investigating the effects of nutritional support (dietary advice (1 RCT), oral nutritional supplements (10 RCT), enteral tube feeding (1 RCT)) versus control on functional outcomes. Meta-analysis of the changes induced by intervention found that while respiratory function (forced expiratory volume in 1s, lung capacity, blood gases) was unresponsive to nutritional support, both inspiratory and expiratory muscle strength (maximal inspiratory mouth pressure +3.86 standard error (SE) 1.89cm H2O, P=0.041; maximal expiratory mouth pressure +11.85 SE 5.54cm H2O, P=0.032) and handgrip strength (+1.35 SE 0.69kg, P=0.05) were significantly improved and associated with weight gains of 2kg. Nutritional support produced significant improvements in quality of life in some trials, although meta-analysis was not possible. It also led to improved exercise performance and enhancement of exercise rehabilitation programmes. This systematic review and meta-analysis demonstrates that nutritional support in COPD results in significant improvements in a number of clinically relevant functional outcomes, complementing a previous review showing improvements in nutritional intake and weight.