Swallowing outcomes in dysphagia interventions in Parkinson’s disease: a scoping review

Objectives: To identify all outcomes, their definitions, outcome measurement instruments (OMIs), timepoints and frequency of measurement applied in clinical trials in oropharyngeal dysphagia (OD) interventions in Parkinson’s disease (PD). This scoping review is the first stage of a larger project establishing a core outcome set for dysphagia interventions in Parkinson’s disease (COS-DIP).

Design: Scoping review.

Methods: Six electronic databases and one trial registry were searched without language restrictions until March 2022. Bibliography lists of included studies were also reviewed. Study screening and data extraction were conducted independently by two reviewers using Covidence. The scoping review protocol is registered and published (http://hdl.handle.net/2262/97652).

Results: 19 studies with 134 outcomes were included. Trial outcomes were mapped to a recommended taxonomy for COSs and merged. 39 outcomes were identified. The most frequently measured were general swallowing-related outcomes, global quality-of-life outcomes and swallowing-related perceived health status outcomes. The applied outcomes, their definitions, OMIs, timepoints and frequency of measurement showed a high variability across all studies.

Conclusions: The high variability of outcomes emphasises the need for an agreed standardised COS. This will inform clinical trial design in OD in PD, increase the quality of OD trials in PD and facilitate synthesising and comparing study results to reach conclusion on the safety and effectiveness of OD interventions in PD. It will not prevent or restrict researchers from examining other outcomes.

Trial registration number: The COS-DIP study, including the scoping review, was registered prospectively with the Core Outcome Measures in Effectiveness Trials Database on 24 September 2021 (www.comet-initiative.org, registration number: 1942).


The objective of this scoping review was to report on all applied outcomes, their definitions, outcome measurement instruments (OMIs) and timepoints and frequency of measurement in (quasi-) randomised controlled trials (RCTs), controlled clinical trials (CCTs) and pilot/feasibility studies with control groups in OD in PD. This extracted information is brought together in a ‘long list of outcomes’ and will be used to inform the development of the COS-DIP. The following research questions were sought to be answered:

What are the outcomes of interest in clinical trials in OD in PD?

How are the outcomes in these clinical trials defined?

How are the outcomes in these clinical trials measured?

At which timepoints and at which frequency are the outcomes in these clinical trials measured?


Julia Hirschwald, Jule Hofacker, Sallyanne Duncan, Margaret Walshe


Journal: BMJ Evidence-Based Medicine
Volume: 28
Issue: 2
Pages: 111 - 118
Year: 2023
DOI: 10.1136/bmjebm-2022-112082

Further Study Information

Current Stage: Completed
Funding source(s): The first author J Hirschwald undertakes this research project as part of a Provost’s PhD Award funded by Trinity College Dublin, Ireland.

Health Area

Disease Category: Rehabilitation

Disease Name: Dysphagia, Parkinson's disease

Target Population

Age Range: 18 - 100

Sex: Either

Nature of Intervention: Any

Stakeholders Involved

Study Type

- Definition
- Systematic review of outcome measures/measurement instruments
- Systematic review of outcomes measured in trials


- Systematic review

A comprehensive search strategy, including two search strings (1) dysphagia and (2) Parkinson’s Disease, was devised with the assistance of a subject librarian. The databases AMED, CINAHL, EMBASE, MEDLINE, Web of Science, ProQuest Dissertations & Theses and trial registry Clinicaltrials.gov were searched from inception to 3 December 2021