In a report online April 18 in the American Journal of Clinical Nutrition, Peter Collins, Rebecca Stratton and Marinos Elia, all from the Institute of Human Nutrition, University of Southampton, United Kingdom, note that the efficacy of nutritional support in the management of malnutrition in COPD is “controversial. Previous meta-analyses, based on only cross-sectional analysis at the end of intervention trials, found no evidence of improved outcomes, they explain.
They searched PubMed, Web of Science and OVID literature databases for randomized controlled trials of nutritional support in COPD. They identified and included in their meta-analysis a total of 13 RCTs involving 439 patients with COPD who were randomly assigned to a treatment group (n=224) or a control group (n=215).
Treatment included nutritional support in the form of dietary advice and a milk powder supplement (1 trial), enteral tube feeding (1 trial) and oral nutritional supplements (ONS, 11 trials). The ONS trials used mostly liquid supplements, some of which were specially formulated for use in patients with COPD. Most of the trials were principally of malnourished (“depleted”) individuals.
The investigators note that previous meta-analyses failed to examine changes in dietary intake. In their analysis, they did examine nutritional intake and found that nutritional support led to a significantly greater increase in both protein and energy intakes.
Specifically, they report that, “An analysis of the changes induced by nutritional support and those obtained only at the end of the intervention showed significantly greater increases in mean total protein and energy intakes with nutritional support of 14.8 g and 236 kcal daily.”
Meta-analyses also showed greater average improvements in favor of nutritional
support for body weight (1.94 kg; p<0.001, 11 studies with 308 subjects) and grip strength (5.3%; p<0.050, 4 studies with 156 subjects), “which was not shown by ANOVA at the end of the intervention, largely because of bias associated with baseline imbalance between groups.”
The authors point out that weight gain of approximately 2 kg in COPD, akin to the magnitude of the mean weight change in favor of the intervention group observed in this review, is likely to be associated with functional and clinical benefits.
Moreover, a post hoc observational analysis of a prospective nutritional intervention trial found that weight loss was reversible through nutritional support and that a significant improvement in survival occurred in depleted and nondepleted patients who gained weight (> 2 kg).
Limitations of the current meta-analysis include a limited number of included studies — 13 total, most that were judged to be of poor quality (10 trials). The fact that most trials used ONS is another limitation; the data are “weak or lacking” for other forms of nutritional support (eg, snacks) or dietary modification/fortification.
They also point out that 10 of the 13 trials were done before 2000, which may reflect that 2000 coincided with the publication of the first Cochrane Review, including most of the current evidence, concluding that nutritional support has no effect on COPD.
“This may have dampened interest in the field; however, it is hoped that the positive findings of this review will highlight the need to undertake further work, including an examination of the interactions that might exist between nutritional supplementation and factors such as malnutrition, inflammatory status, and graded physical activity in both stable disease and infective exacerbations of COPD,” the authors conclude.
One of the authors on the paper is an employee of Nutricia Ltd. None of the other authors declared a conflict of interest.