Nutritional supplementation for stable chronic obstructive pulmonary disease

Abstract

Individuals with chronic obstructive pulmonary disease (COPD) and low body weight have impaired pulmonary status, reduced diaphragmatic mass, lower exercise capacity and higher mortality than those who are adequately nourished. Nutritional support may be useful for their comprehensive care. To assess the impact of nutritional support on anthropometric measures, pulmonary function, respiratory and peripheral muscles strength, endurance, functional exercise capacity and health-related quality of life (HRQoL) in COPD.If benefit is demonstrated, to perform subgroup analysis to identify treatment regimens and subpopulations that demonstrate the greatest benefits. We identified randomised controlled trials (RCTs) from the Cochrane Airways Review Group Trials Register, a handsearch of abstracts presented at international meetings and consultation with experts. Searches are current to April 2012. Two review authors independently selected trials for inclusion, assessed risk of bias and extracted the data. Decisions were made by consensus. We used post-treatment values when pooling the data for all outcomes, and change from baseline scores for primary outcomes. We used mean difference (MD) to pool data from studies that measured outcomes with the same measurement tool and standardised mean difference (SMD) when the outcomes were similar but the measurement tools different. We contacted authors of the primary studies for missing data.We established clinical homogeneity prior to pooling. We presented the results with 95% confidence intervals (CI) in the text and in a 'Summary of findings' table. We included 17 studies (632 participants) of at least two weeks of nutritional support. There was moderate-quality evidence (14 RCTs, 512 participants, nourished and undernourished) of no significant difference in final weight between those who received supplementation and those who did not (MD 0.69 kg; 95% CI -0.86 to 2.24). Pooled data from 11 RCTs (325 undernourished patients) found a statistically significant weight gain (MD 1.65 kg; 95% CI 0.14 to 3.16) in favour of supplementation; three RCTs (116 mixed population) found no significant difference between groups (MD -1.28 kg; 95% CI -6.27 to 3.72). However, when analysed as change from baseline, there was significant improvement with supplementation: 14 RCTs (five of which had imputed SE), MD 1.62 kg (95% CI 1.27 to 1.96 ); 11 RCTs (malnourished), MD 1.73 kg (95% CI 1.29 to 2.17) and three RCTs (mixed), MD 1.44 kg (95% CI 0.68 to 2.19).There was low-quality evidence from five RCTs (six comparisons, 287 participants) supporting a significant improvement from baseline for fat-free mass/fat-free mass index (SMD 0.57; 95% CI 0.04 to 1.09), which was larger for undernourished patients (three RCTs, 125 participants; SMD 1.08; 95% CI 0.70 to 1.47). There was no significant change from baseline noted for adequately nourished patients (one RCT, 71 participants; SMD 0.27; 95% CI -0.20 to 0.73), or for a mixed population (two RCTs, 91 participants; SMD -0.05; 95% CI -0.76 to 0.65).There was moderate-quality evidence from two RCTs (91 mixed participants) that nutritional supplementation significantly improved fat mass/fat mass index from baseline (SMD 0.90; 95% CI 0.46 to 1.33).There was low-quality evidence (eight RCTs, 294 participants) of an increase in mid-arm muscle circumference change (MAMC; MD 0.29; 95% CI 0.02 to 0.57).There was low-quality evidence (six RCTs, 125 participants) of no significant difference in change from baseline scores for triceps measures (MD 0.54; 95% CI -0.16 to 1.24).There was low-quality evidence (five RCTs, 142 participants) of no significant difference between groups in the six-minute walk distance (MD 14.05 m; 95% CI -24.75 to 52.84), 12-minute walk distance or in shuttle walking.