Fidelity in Behavioral Interventions for Oropharyngeal Dysphagia in Parkinson's Disease: A Systematic Review

Measuring fidelity of delivery and engagement in the methods of a trial helps us to understand whether planned interventions were effective. Treatment fidelity is critical in proving that change in study outcomes is due to the intervention itself and not to variability in its implementation or measurement. Existing reviews of oropharyngeal dysphagia (OD) interventions for Parkinson's disease (PD) have not systematically scrutinized fidelity within clinical trials. This study aimed to examine treatment fidelity in behavioral interventions for OD in PD and provide information about the reliability of existing study findings on behavioral interventions. All published and unpublished randomized controlled trials (RCTs) regarding behavioral interventions for OD in PD were sought. A comprehensive search of eight electronic databases was performed from inception to January 2019 and updated in April 2020. Gray literature was explored to minimize publication bias. No language or date restrictions were applied. Data were extracted by two independent reviewers with a third mediator. The National Institutes of Health Behavior Change Consortium Treatment Fidelity checklist was used to assess fidelity. From the 4998 references identified, eight studies met the inclusion criteria. Behavioral interventions in the included studies varied. The level of treatment fidelity was rated as low across all studies included in the review. The review concluded that low levels of treatment fidelity adherence in RCTs on dysphagia interventions in PD undermine the interpretation of the validity and reliability of study findings along with successful replication of these interventions in research and clinical practice.