Incidence of postoperative dysphagia/dysphonia between cervical disc replacement and anterior cervical discectomy and fusion: a comprehensive evaluation

The aim of this study is to compare the incidence of postoperative dysphagia/dysphonia between anterior cervical discectomy and fusion (ACDF) with an anterior plate and cervical disc replacement (CDR). PubMed, EMBASE, Web of science, Ovid, Cochrane library and China Knowledge Resource Integrated Database (until March 1, 2016) were searched. RCTs that reported the number of patients who suffered from dysphagia/dysphonia after CDR and ACDF were included. Relative risk (RR) with 95% confidence interval (95% CI) was calculated for dichotomous outcomes. Sensitivity analyses and publication bias were performed. Finally 12 RCTs with a total of 1948 patients who underwent CDR and 1552 patients who underwent ACDF were included in this meta-analysis. No statistically significant difference concerning the incidence of postoperative dysphagia/dysphonia between CDR and ACDF was observed (RR = 0.809, 95% CI [0.610, 1.073], z = 1.47, P = 0.142). A significant lower incidence of postoperative dysphagia in CDR group compared with patients in ACDF group was observed (RR = 0.751, 95% CI [0.588, 0.960], z = 2.29, P = 0.022). No statistically significant difference concerning the incidence of postoperative dysphonia between CDR and ACDF was observed (RR = 0.435, 95% CI [0.133, 1.423], z = 1.38, P = 0.169). CDR may reduce the incidence of postoperative dysphagia but not dysphagia/dysphonia as a whole part and dysphonia compared with ACDF with an anterior plate. Since lack of gold standard diagnostic criteria and details of dysphagia or dysphonia in the included original studies, results of this meta-analysis should be validated by future RCTs which use gold standard diagnostic criteria and specially focused on details of postoperative dysphagia and dysphonia.