Fatigue, post-exertional malaise and orthostatic intolerance: a map of Cochrane evidence relevant to rehabilitation for people with post COVID-19 condition.

INTRODUCTION
Rehabilitation focuses on impairments, activity limitations and participation restrictions being informed by the underlying health condition. In the current absence of direct "evidence on" rehabilitation interventions for people with post-COVID-19 condition (PCC), we can search and synthesize the indirect "evidence relevant to" coming from interventions effective for the symptoms of PCC in other health conditions. The World Health Organization (WHO) required this information to inform expert teams and provide specific recommendations in their Guidelines. With this overview of reviews with mapping, we aimed to synthesize in a map the Cochrane evidence relevant to rehabilitation for fatigue, post-exertional malaise and orthostatic intolerance due to PCC.


EVIDENCE ACQUISITION
We searched the last five years' Cochrane Systematic Review (CSRs) using the terms "fatigue," "orthostatic intolerance," "rehabilitation" and their synonyms 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
Out of 1397 CSRs published between 2016 and 2021, we included 32 for fatigue and 4 for exercise intolerance. They provided data from 13 health conditions, with cancer (11 studies), chronic obstructive pulmonary disease (7 studies), fibromyalgia (4 studies), and cystic fibrosis (3 studies) being the most studied. Effective interventions for fatigue included exercise training and physical activities, telerehabilitation and multicomponent and educational interventions. Effective interventions for exercise intolerance included combined aerobic/anaerobic training and integrated disease rehabilitation management. The overall quality of evidence was low to very low and moderate in very few cases. We did not identify CSRs that specifically addressed post-exertional malaise or orthostatic intolerance.


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.