The effects of neuromuscular electrical stimulation on hospitalised adults: systematic review and meta-analysis of randomised controlled trials

Introduction: Neuromuscular electrical stimulation (NMES) is a treatment to prevent or reverse acquired disability in hospitalised adults. We conducted a systematic review and meta-analysis of its effectiveness.Method: We searched MEDLINE, EMBASE, Cumulative Index to Nursing & Allied Health (CINAHL) and the Cochrane library. Inclusion criteria: randomised controlled trials of hospitalised adult patients comparing NMES to control or usual care. The primary outcome was muscle strength. Secondary outcomes were muscle size, function, hospital length of stay, molecular and cellular biomarkers, and adverse effects. We assessed risk of bias using the Cochrane risk-of-bias tool. We used Review Manager (RevMan) software for data extraction, critical appraisal and synthesis. We assessed certainty using the Grading of Recommendations Assessment, Development and Evaluation tool.Results: A total of 42 papers were included involving 1,452 participants. Most studies had unclear or high risk of bias. NMES had a small effect on muscle strength (moderate certainty) (standardised mean difference (SMD) = 0.33; P < 0.00001), a moderate effect on muscle size (moderate certainty) (SMD = 0.66; P < 0.005), a small effect on walking performance (moderate certainty) (SMD = 0.48; P < 0.0001) and a small effect on functional mobility (low certainty) (SMD = 0.31; P < 0.05). There was a small and non-significant effect on health-related quality of life (very low certainty) (SMD = 0.35; P > 0.05). In total, 9% of participants reported undesirable experiences. The effects of NMES on length of hospital stay, and molecular and cellular biomarkers were unclear.Conclusions: NMES is a promising intervention component that might help to reduce or prevent hospital-acquired disability.