Nutritional supplementation during pulmonary rehabilitation in COPD: A systematic review

Uptake of nutritional supplementation during pulmonary rehabilitation (PR) for people with chronic obstructive pulmonary disease (COPD) has been limited by an absence of rigorous evidence-based studies supporting use. The objective was to report and summarise the current evidence supporting the use of nutritional supplementation to improve outcomes during PR in stable COPD patients. A systematic search was conducted up to 7 August 2019 (registration number CRD42018089142). The preferred reporting items for systematic reviews and meta-analyses guidelines were used. Six databases were included: Medical Literature Analysis and Retrieval System Online or MEDLARS Online, Allied and Complementary Medicine Database, the Cochrane Database of Systematic Reviews, Excerpta Medica dataBASE, Cumulative Index of Nursing and Allied Health Literature and Web of Science. This systematic search generated 580 initial matches, of which 22 studies (917 COPD participants) met the pre-specified criteria and were included. Sixteen of 19 studies that used nutritional supplements in addition to PR did not show additional benefit compared to PR alone when measuring exercise capacity. Nutritional supplements significantly increased body weight in 7 of 11 studies. Body mass index increased significantly in two of six studies. Handgrip strength did not improve, while quadriceps muscle strength significantly improved in 3 of 11 studies. Four of eight studies showed a significant improvement in inspiratory muscle function. Only 2 of 14 studies demonstrated a significant improvement in quality of life with supplementation in addition to PR. There remains insufficient evidence on the effect of nutritional supplementation on improving outcomes during PR in patients with COPD due to heterogeneity in supplements, outcome measures and PR programmes. Therefore, controversy remains and further research is needed.