Rong-chang Chen, Xiao-ying Li, Li-li Guan, Bing-peng Guo, Wei-liang Wu, Zi-qing Zhou, Ya-ting Huo, Xin Chen, Lu-qian Zhou

Patients with COPD often experience skeletal muscle dysfunction. For those who are unable or unwilling to undertake physical training, neuromuscular electrical stimulation (NMES) may provide an alternative method of rehabilitation. The purpose of this meta-analysis was to investigate the controversial topic of whether this therapy is effective in patients with moderate-to-severe COPD. We pooled data from nine trials published between January 9, 2002 and January 4, 2016 across PubMed, Embase, Cochrane Central Register of Controlled Trials, Google Scholar, and relevant websites for randomized controlled trials. In these trials, patients with moderate-to-severe COPD were randomly allocated to receive NMES. Primary outcomes were quadricep strength and exercise capacity. The secondary outcome was health-related quality of life. We extracted data from 276 patients. NMES contributed to statistically improved quadricep strength (standardized mean difference 1.12, 95% confidence interval [CI] 0.64-1.59, I(2)=54%; P<0.00001) and exercise capacity, including longer exercise distance (weighted mean difference 51.53, 95% CI 20.13-82.93, I(2)=90%; P=0.001), and longer exercise endurance (standardized mean difference 1.11, 95% CI 0.14-2.08, I(2)=85%; P=0.02). There was no significant difference in St George's Respiratory Questionnaire scores (weighted mean difference -0.07, 95% CI -2.44 to 2.30, I(2)=56%; P=0.95). NMES appears an effectual means of enhancing quadricep strength and exercise capacity in moderate-to-severe COPD patients. Further research is demanded to clarify its effect on other outcomes and determine the optimal parameters for an NMES program.