Dysphagia, dysphonia and olfactory disease: a map of Cochrane evidence relevant to rehabilitation for people with post COVID-19 condition

INTRODUCTION: Currently, no evidence exists on specific treatments for post COVID-19 condition (PCC). However, rehabilitation interventions that proved effective for similar symptoms in other health conditions could be applied to people with PCC. With this overview of systematic reviews with mapping, we aimed to describe the Cochrane evidence on rehabilitation interventions proposed for dysphagia, dysphonia and olfactory dysfunction in different health conditions that can be relevant for PCC. EVIDENCE ACQUISITION: We searched the last five years’ Cochrane Systematic Review (CSRs) using the terms “dysphagia,” “swallowing disorder,” “dysphonia,” “voice disorder,” “olfactory dysfunction,” “smell changes” and “rehabilitation” in the Cochrane Library. We extracted and summarized the available evidence using a map. We grouped the included CSRs for health conditions and interventions, indicating the effect and the quality of evidence. EVIDENCE SYNTHESIS: We found 170 CSRs published between 2016 and 2021 and 1 was included. It provided data on dysphagia in acute and subacute stroke. Interventions included were acupuncture, neuromuscular electrical stimulation, transcranial magnetic stimulation and behavioral interventions, and swallowing therapy, with very low- to moderate-quality evidence. We did not find any CSR on dysphonia and olfactory disease. CONCLUSIONS: These results are the first step of indirect evidence able to generate helpful hypotheses for clinical practice and future research. They served as the basis for the three recommendations on treatments for these PCC symptoms published in the current WHO Guidelines for clinical practice.