Electrical stimulation as a therapeutic approach in obstructive sleep apnea — a meta-analysis

Purpose Electrical stimulation of the upper airway dilator muscles is an emerging treatment for obstructive sleep apnea (OSA). Invasive hypoglossal nerve stimulation (HNS) has been accepted as treatment alternative to continuous positive airway pressure (CPAP) for selected patients, while transcutaneous electrical stimulation (TES) of the upper airway is being investigated as non-invasive alternative. Methods A meta-analysis (CRD42017074674) on the effects of both HNS and TES on the apnea-hypopnea index (AHI) and the Epworth Sleepiness Scale (ESS) in OSA was conducted including published evidence up to May 2018. Random-effects models were used. Heterogeneity and between-study variance were assessed by I 2 and τ 2 , respectively. Results Of 41 identified clinical trials, 20 interventional trials ( n = 895) could be pooled in a meta-analysis (15 HNS [ n = 808], 5 TES [ n = 87]). Middle-aged (mean ± SD 56.9 ± 5.5 years) and overweight (body mass index 29.1 ± 1.5 kg/m 2 ) patients with severe OSA (AHI 37.5 ± 7.0/h) were followed-up for 6.9 ± 4.0 months (HNS) and 0.2 ± 0.4 months (TES), respectively. The AHI improved by − 24.9 h −1 [95%CI − 28.5, − 21.2] in HNS (χ 2 79%, I 2 82%) and by − 16.5 h −1 [95%CI − 25.1, − 7.8] in TES (χ 2 7%, I 2 43%; both p < 0.001). The ESS was reduced by − 5.0 (95%CI − 5.9, − 4.1) ( p < 0.001). Conclusion Both invasive and transcutaneous electrical stimulation reduce OSA severity by a clinically relevant margin. HNS results in a clinically relevant improvement of symptoms. While HNS represents an invasive treatment for selected patients with moderate to severe OSA, TES should be further investigated as potential non-invasive approach for OSA.