Dysphagia treatments in Parkinson's disease: A systematic review and meta-analysis

The majority of patients with Parkinson's disease (PD) develop oropharyngeal dysphagia during the course of their disease. However, the efficacy of dysphagia treatments for these patients remains controversial. Therefore, we conducted this systematic review and meta-analysis to evaluate treatment efficacy based on the evidence from randomized controlled trials (RCTs).

Five electronic databases were systematically searched from inception date to April 2022. Two reviewers independently extracted and analyzed the data. The outcome measures were changes in swallowing-related characteristics based on instrumental swallowing assessments.

An initial search identified 187 RCT studies of relevance. After screening, nine studies with a total sample size of 286 were included in the meta-analysis. The pooled effect size for all dysphagia treatments compared with control comparators was significant and medium (SMD [95% CI] = 0.58 [0.22, 0.94], p = 0.001; I²  = 50%). Subgroup analysis revealed a significant and medium pooled effect size for stimulation treatments (brain stimulation, peripheral neurostimulation and acupuncture) (SMD [95% CI] = 0.54 [0.15, 0.92]; p = 0.006; I²  = 22%). Specifically, the effect sizes for the single RCTs on neuromuscular stimulation (SMD [95% CI] = 1.58 [0.49, 2.86]; p = 0.005) and acupuncture (SMD [95% CI] = 0.82 [0.27, 1.37]; p = 0.003) were significant and large.

Our results showed that overall, dysphagia treatments, particularly stimulation treatments, can potentially benefit PD patients. However, given the limited number of small RCTs for each type of treatment, the evidence remains weak and uncertain. Further large-scale, multicenter RCTs are warranted to fully explore their clinical efficacy in the PD population.