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Protocol for the Development of a Core Outcome
Set for Lateral Elbow Tendinopathy (COS-LET)
Marcus Bateman ( marcus.bateman@nhs.net )
University Hospitals Derby & Burton NHS Foundation Trust https://orcid.org/0000-0002-3203-506X
Jonathan P Evans
University of Exeter Medical School
Viana Vuvan
University of Queensland
Valerie Jones
Sheeld Teaching Hospitals NHS Foundation Trust
Adam C Watts
Wrightington, Wigan and Leigh NHS Foundation Trust
Joideep Phadnis
Brighton and Sussex University Hospitals NHS Trust
Leanne Bisset
Grith University Menzies Health Institute Queensland
Bill Vicenzino
University of Queensland
Study protocol
Keywords: Lateral elbow tendinopathy, tennis elbow, core outcome set
DOI: https://doi.org/10.21203/rs.3.rs-340653/v1
License: This work is licensed under a Creative Commons Attribution 4.0 International License.
Read Full License
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Abstract
Background
Lateral elbow tendinopathy (LET) is a common condition that can cause signicant disability and
associated socioeconomic cost. Although it has been widely researched, outcome measures are highly
variable which restricts evidence synthesis across studies. In 2019 a working group of international
experts, health care professionals and patients, in the eld of tendinopathy (International Scientic
Tendinopathy Symposium Consensus (ICON) Group) published the results of a consensus exercise
dening the nine core domains that should be measured in tendinopathy research. The aim of this study
is to develop a Core Outcome Set (COS) for LET mapping to these core domains. The primary output will
provide a template for future outcome evaluation of LET. In this protocol we detail the methodological
approach to the COS-LET development.
Methods
This study will employ a three-phase approach. (1) A systematic review of studies investigating LET will
produce a comprehensive list of all instruments currently employed to quantify treatment effect or
outcome. (2) Instruments will be matched to the list of nine core tendinopathy outcome domains by a
Steering Committee of clinicians and researchers with a specialist interest in LET resulting in a set of
candidate instruments. (3) An International three-stage Delphi Study will be conducted involving
experienced clinicians, researchers and patients. Within this Delphi Study candidate instruments will be
selected based upon screening using the Outcome Measures in Rheumatology (OMERACT) truth,
feasibility and discrimination lters with a threshold of 70% agreement set for consensus.
Conclusions
There is currently no COS for the measurement or monitoring of LET in trials or clinical practice. The
output from this project will be a minimum COS recommended for use in all future English-language
studies related to LET. The ndings will be published in a high-quality journal and disseminated widely
using professional networks, social media and via presentation at international conferences.
Key Points
There is wide variability in the outcome measures used in lateral elbow tendinopathy research.
This protocol outlines the methodology used to derive a standardised set of validated outcome
measures.
The Core Outcome Set – Lateral Elbow Tendinopathy (COS-LET) will provide guidance on the
minimum recommended outcomes to be used in future research, which, If implemented broadly, with
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better represent the core domains of tendinopathy and assist in future systematic review and meta-
analysis.
Background And Objectives
Pain arising from the tendons on the lateral side of the elbow is common in adults, particularly in middle-
age.1 Historically it has been known by various names such as ‘lateral epicondylitis’, or ‘Tennis Elbow’ but
the current accepted description is ‘lateral elbow tendinopathy’(LET).2 The condition has a high economic
burden3,4 and, as no universal consensus guidelines for treatment exist, is a topic of continued interest to
researchers. A wide array of interventions have been studied including surgery, numerous injectate
formulations, electrotherapies and exercise. The goal of these interventions is to restore, improve or
preserve function and well-being, with the effect of the intervention quantied by the patient using
standardised measurement instruments. It has been recognised that there is substantial heterogeneity of
instrument use in elbow pathology and specically for LET.5 With no clear consensus on which
instruments most accurately represent patient’s LET-related health status, comparison of effectiveness
research and evidence synthesis/meta-analysis has been signicantly hampered. Without clear
consensus on which outcome measure best reects the patients experience of LET, it is likely that
agreement on treatment protocols will remain unattainable.6,7
In 2019 a working group of international experts in the eld of tendinopathy (International Scientic
Tendinopathy Symposium Consensus (ICON) Group) comprising researchers, health care professionals
and patients, published a consensus document dening the core domains of patient and clinician interest
in tendinopathy, against which pathology-specic outcome measures should be recommended.8 The
robust methodology involved a scoping review of tendinopathy research papers, published during a 10-
year period, to identify measures used and to produce a base list of 24 possible domains representing all
facets of a patient’s life that may be affected by the condition. A three-stage Delphi process was then
conducted involving experienced clinicians, researchers and patients from across the world to establish a
consensus on which domains should be included in a core outcome set.
The nine domains that were recommended are as follows:
1. patient rating of condition (a single assessment numerical evaluation)
2. participation in life activities (day to day, work, sport)
3. pain on activity/loading
4. function (a patient-rated measure of function not relating to intensity of pain)
5. psychological factors
6. physical function capacity (including strength)
7. disability (composite scores of pain and pain-related disability)
8. quality of life (general well-being)
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9. pain over a specied time
Numerous methods exist to measure each of these domains, so the proposed next step is to identify the
suitable measures of these domains within a pathology specic context for each of the major
tendinopathies. In keeping with good practice for instrument selection, each instrument will need to be
both practical to perform (based on cost, patient burden and availability) and of high quality (valid,
reliable, acceptable and interpretable).9 The result will be a minimum set of outcome measures for each
specic condition to be used in future research that allows direct comparison between different studies
across the nine domains. The Core Outcome Measures in Effectiveness Trials (COMET) Initiative provides
guidance on this process and a register of specic projects (http://www.comet-initiative.org). Following
this guidance, the aim of this paper is to outline the protocol to be used in the development of a patient,
clinician and clinician focused core outcome set (COS) for lateral elbow tendinopathy, although a similar
methodology might be applied to other tendinopathies in future.
Scope
This COS relates to all adults diagnosed with LET and applies to interventional research (including
surgical and non-surgical) and longitudinal assessment. The COS will only apply to the English language.
Method
This study will utilise an International group of patients, researchers and clinicians to reach a consensus
on the core outcome set for LET assessment. The project is registered with the COMET Initiative:
http://www.comet-initiative.org/Studies/Details/1497 and this protocol is written following the Core
Outcome Set Standardised Protocol (COS-STAP) checklist.10
Study Design
The COS-LET development will progress through three distinct phases: (1) An update of the 2019
systematic review assessing patient reported instruments in the assessment of LET will be undertaken,11
this will aim to identify additional outcomes and to gather data on non-patient reported instruments
utilised in LET assessment; (2) Domain matching of the individual instruments to the core domains of
tendinopathy, the aim will be to ensure comprehensive domain coverage, identify gaps in coverage and to
exclude instruments that do not match to the requisite domains; and (3) an international patient,
researcher and clinician Delphi Study, the aim of which will be to assess the acceptability, rationale and
metric properties of the instruments, thereby resulting in a selection of instruments that could be included
in the COS. Following the three development stages, an expert panel of patients, researchers and
clinicians will ratify the nal COS.
Steering Committee
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This international committee will be comprised of eight experts in the eld of LET. There will be a mix of
researchers and clinicians, both from surgical and physiotherapy backgrounds. There will also be a mix
of nationalities, age and sex to give a broad spectrum of views. A practical challenge will be the
coordination of meetings and study tasks given the spread of geographical locations of those involved.
Meetings will be scheduled using an online availability tool that accounts for different time zones
(www.doodle.com). Files will be stored on a secure cloud platform (www.dropbox.com) with access to
view and edit given only to the Steering Committee. Meetings will be held via an online video conference
platform (www.zoom.us) with minutes documented and meetings recorded in video format. This allows
Steering Committee members unable to attend meetings to accurately review matters discussed. The
steering committee will agree on the nal protocol and will be in regular contact throughout the entire
process up to and including the development of the nal COS. The steering committee will independently
conduct stages one and two of the protocol and will remain involved in stage three and nal ratication.
Stakeholders and Recruitment
The steering committee are committed to ensuring the COS development is conducted by a broad and
representative population of researchers, clinicians, and most importantly, patients. The Delphi Study
population will include experienced clinicians and researchers nominated by the Steering Committee and
also identied by their reputation as elbow specialists or prior publications related to LET. Additionally, a
search of the Expertscape and SCOPUS databases by author and ltered by the terms ‘tennis elbow’ and
‘trial’ will identify a list of other researchers to approach. Representation from a range of nationalities,
with a spread of ethnicity and sex will be ensured. Patient representation will be achieved through
invitation by the clinicians on the Steering Committee and those in the Delphi group will be asked to share
the survey with their patients. A target number of 20 clinicians/researchers and 5 patients will be
included.
Phase 1: Systematic review: Instruments currently employed and their prevalence of use
In 2019, Evans et al published a systematic review of English language outcome measures used in
surgical and non-surgical trials for LET, but only instruments related to elbow pain and function were
included.11 The study reported on the psychometric assessment of 15 patient-focused instruments in LET
reported in 105 articles. The published ndings and unpublished additional data, with permission of the
lead author, will be used to identify all LET trials up to 2017. The searches will be repeated to include
papers from 2017 onwards to subsequently provide a comprehensive list of all trials related to LET
(search strategy available in Supplementary File 1 from the original publication
https://tinyurl.com/y5n667be).11 The previously utilised search strategy constructed using MeSH and
free-text terms will be run in MEDLINE and Embase accessed through OVID Silver Platter. The search
results will be screened initially by title and abstract by two reviewers independently of each other using
the online Rayyan tool to facilitate this process being completed in different geographical locations.12
Any points of disagreement will be discussed and reconciled with the help of a third reviewer if required.
All study methodologies will be included with the exception of research protocols, case studies and small
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case series of less than ve patients as these will add little value. From the extracted lists of the 105
previously identied articles, and articles identied from 2017 onwards, a
de novo
data extraction will be
undertaken. Extracted data will include, all outcome instrument used (including patient reported, clinician
reported, LET specic, upper limb or joint specic, generic and physical examination (e.g. range of motion
or strength) instruments), number of patients included in the study and full details of any novel
instruments.
The output from phase one will be a comprehensive list of all reported outcome instruments and their
prevalence of use within the entire body of literature on LET.
Phase 2: Domain Mapping
The eight Steering Committee members will map the individual instruments to the nine core tendinopathy
domains8 using the Outcome Measures in Rheumatology (OMERACT) truth (part a) and feasibility
lters.13 The truth lter (part a) assesses content and face validity whilst the feasibility lter assesses
whether the instrument is practical to use (for example: is it too time-consuming, costly, requiring
specialist equipment?). For each lter a trac-light rating is applied. A green light means the instrument
is included. An amber light means it is included with caution. A red light means it should be excluded. At
this stage if any instruments are rated red it will be excluded. The Steering Committee will split into four
pairs to divide the workload. Each individual will assess whether their allocated instruments map to any
of the nine tendinopathy domains using the instrument’s published development article or manual as a
reference guide.8 The results will then be compared with their co-reviewer and any points of disagreement
discussed. In cases where a conclusion cannot be agreed a third member will cast a deciding vote.
The outcome from phase two will be a list of domain mapped candidate instruments that demonstrate
adequate content and face validity and are deemed feasible for use. All instruments that do not pass
these requirements will be excluded at this stage.
Phase 3: Delphi Consensus
Following the collation of a list of candidate instruments an international multidisciplinary Delphi Study
will be performed. An online Delphi questionnaire will be shared with the stakeholder group through
Qualtrics survey software (Provo, Utah, USA). The Delphi questionnaire will contain a participant
information sheet and consent ltering questions (i.e. ‘Yes’ is checked to consent and proceed to the
questionnaire; ‘No is checked to not consent and be exited from the questionnaire). The Delphi
questionnaire will list each instrument available for each of the nine domains with an associated
reference document including the instruments original development article and/or manual. Respondents
will rate each instrument using the OMERACT trac light system for truth and feasibility as for validity
and feasibility. Additionally, they will be asked their opinion as to whether each instrument should be
included in the nal COS. Any instruments that are rated of limited importance (red) by 70% or more
respondents will be excluded. This threshold is in line with the ICON Group consensus utilised for the
development of the core domains.8 There will also be the option at this stage for respondents to list any
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other instruments that have not previously been included if they think that inclusion is important or
critical. These instruments will then be scrutinised by the Steering Committee using the OMERACT truth
(part a) and feasibility lters.
Following exclusion of instruments of limited importance and inclusion of any new instruments the
Steering Committee the OMERACT truth (part b) and discrimination lters will be applied with a focus on
the measurement properties of the instruments. Specically, this will assess each instrument on the
strength of its associated psychometric properties, as reported in development or validation articles. The
metric properties that will be reviewed include the construct validity (does the instrument measure what it
is purports to measure, demonstrated through correlation with gold standard or associated instruments ),
its reliability (that the items of the instrument are coherent within its specied target domain, quantied
by Cronbach’s α), repeatability (its stability on repeated testing with no clinical change, quantied with
test-retest reliability), the instrument responsiveness (does it change with clinical change, often quantied
by effect size) and interpretability (its ability to differentiate between groups, often represented by the
minimal important difference). This will be done using an appropriate method, such as the EMPRO tool14,
by pairs of reviewers from the research team and a third reviewer will cast a deciding vote in the case of
disagreement. Again, these will be rated using the OMERACT trac-light system.
The Steering Committee will then compile a report summarising the ndings of Round 1 of the Delphi
Study showing the trac light rating of each instrument within their associated matched domain and
subsequent outcome of the truth (part b) and discrimination lters. The stakeholder group will then be
invited to participate in the second round of the Delphi Study. They will be asked to read the summary
report and re-rate each instrument using the OMERACT trac light system. The responses will be
analysed and those instruments rated of low importance (red) by 70% or more of stakeholders will be
excluded unless they are the only measure of a specic domain. For each domain, instruments rated
green by 70% or more of stakeholders will be included in the nal COS unless there are more than one
selected for that domain. In the scenario of multiple appropriate measures covering a single domain a
decision will be made following discussion in the third-round Delphi consensus meeting. Similarly, if a
domain has no identied instruments, then those rated amber will be will enter the third-round Delphi
consensus meeting. The online surveys are expected to take no longer than 60 minutes to complete and
can be undertaken over several sessions.
The third-round Delphi consensus meeting will be held online via Zoom to maximise participation from
clinician, researcher and patient stakeholders. Prior to the third-round Delphi consensus meeting semi-
structured qualitative interviews will be conducted with patient contributors by the research team to
ensure that the patient voice is heard, due to concerns that patients may nd voicing their opinions in a
group environment intimidating. The anonymised ndings will be used to prompt discussions in the
Delphi consensus meeting. Following discussions, a nal ratication process will be undertaken to
develop the COS-LET. If a domain has a single instrument with green consensus agreement, this will be
included in the COS-LET. For any domain that does not have a single green measurement instrument
there will be a nal vote on which instrument to include. This will be done using a Nominal Group
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Technique using a 70% threshold for consensus. Voting will be done anonymously using an online
polling system. For domains where there is no instrument rated green with 70% consensus, we will make
recommendations for research to determine a measure and recommend an instrument that may be used
in the interim.
A diagrammatical summary of the method is shown in Figure 1.
Delphi study sample size
The question of participant numbers is dependent on the minimally sucient number to constitute a
representative pooling of judgments 15. Wide variations in expert numbers have been reported in Delphi
studies 16, though nominally they tend to be within 20-60 17.
This study will aim to recruit a minimum of 30 participants. The primary steering group from phase one
and two will comprise of eight members. Therefore, an additional 22 participants will be required during
the phase three Delphi study, however there will be no maximum. Participant retention is an important
component of Delphi studies therefore the iterations of the Delphi will require retention of >60% of
respondents. Though it has been reported that the reliability of composite judgments increases with
respondent numbers, there is little empirical evidence on the effect of participant numbers on reliability or
validity of the consensus process if the panel composition is appropriate. 18
Final development
The goal of this body of work is to achieve a pragmatic COS that will be readily employable. Our attention
will be set to the production of a COS that achieves a clear patient focus, representing the outcomes
important to them. It should be comprehensive but also user friendly, wherein there is minimised burden
both to the participant completing the outcome scores and the researcher in its delivery and
interpretation.
Ethical considerations and Data collection
In concordance with the principles of Good Clinical Practice (GCP), phase one and two, whereby the
committee membership undertake non-patient facing activity utilising previously published literature, that
formal ethical approval will not be required. For the Delphi Study Ethical approval has been granted by
the University of Queensland research ethics committee (reference number 2020001340).
All data will be handled condentially and in accordance with the General Data Protection Regulation
(GDPR). Access to any personally identiable data will be strictly limited.
Dissemination:
The nal report detailing the instruments selected in the COS will be submitted for publication in a high-
quality peer-reviewed international journal and will be presented at relevant international scientic
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meetings such as the International Scientic Tendinopathy Symposium and International Congress of
Shoulder and Elbow Surgery. The key points, infographic and links to the nal report will also be
disseminated via social media platforms.
Results
Not applicable for a protocol article
Discussion
This protocol has been designed to comply with contemporary standards and expectations of a core
outcome set development, however, the authors recognise that certain limitations are inherent in an
outcome study design of this formulation.
Outcome selection
Within the systematic search component of phase one, the search strategy development is guided by
previously published search strategies for systematic reviews of interventions in elbow pathology 19 and
for the identication of outcome measures 20, along with terms specically selected in order to capture
names of relevant instruments published in previous systematic reviews of elbow specic rating scales
21-24. Although the intention is that this is a sensitive as possible, it remains a possibility that instruments
will not be identied through this process. All stakeholders will be consulted on whether they are aware of
further measures that should be included.
To assist in the running of the Delphi Study, the list of included instruments will be honed as part of the
domain matching process, wherein all unmatched instruments will be removed. This process will rely on
the face validity assessment of the instrument by two reviewers and risks unwarranted exclusion of
instruments. Again, to ameliorate this risk, the steering committee will have oversight on the included and
excluded measures.
Stakeholder selection
Careful consideration has been given to the composition of both the steering group and larger
stakeholder groups selection. Efforts will be made to invite a broad and representative selection of
contributors from an international multidisciplinary pool including a patient sample. However, the authors
recognise that certain groups may be unrepresented or omitted. The anonymity of the Delphi Study
process will assist in protection of bias from the inuence of certain factions of a stakeholder group, but
it remains a possibility that certain sub-groups may hold more inuence. To monitor this risk, the steering
group will maintain oversight and a stratied analysis of the Delphi results will be undertaken to assess
for skewing.
Consensus population
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The decision to restrict the COS-LET to English language use is an inherent limitation in its utility, however
this decision has been made on a pragmatic basis. Restriction of language eligibility will allow a clearer
communication between steering and stakeholder groups and will mean that the Delphi Study can be
delivered in a single language. We also recognise that outcome instrument cross-cultural validation
necessitates a meticulous methodological undertaking in itself 9, therefore to recommend instruments
applicable across language becomes very challenging and beyond the scope of this protocol.
Outcome measures
The output from this study will be a recommended COS of instruments. However, if particular domains
are covered equally well by multiple instruments’, a decision may be made to allow the recommendation
of multiple instruments for use at the discretion of the future user. It is also beyond the scope of this work
to designate which of the COS-LET instruments should be primary outcomes or at which timepoints they
are to be collected. These aspects will be discussed in depth within the nal article.
Conclusion
This protocol describes the methods that will be applied in the development of the Core Outcome Set –
Lateral Elbow Tendinopathy (COS-LET). A rigorous approach that complies to the standardised
expectations of core outcome set development has been proposed. The aim will be the production of
patient-focused, user-friendly and comprehensive guidance on outcome set selection with the goal of
broad implementation into future LET research.
Declarations
Ethical approval
Ethical approval is not required for the publication of this study protocol. Approval for the Delphi study
has been granted by the University of Queensland (reference number 2020001340)
Consent for publication
All authors have given consent for publication. No individual level data is presented.
Availability of data and material
This protocol has been registered with the COMET initiative. Full data transparancy will be provided with
the publication of the nal study ndings
Competing interests
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Marcus Bateman declares that he has no competing interests
Jonathan P Evans declares that he has no competing interests
Adam C. Watts declares that he has no competing interests
JoideepPhadnis declares that he has no competing interests
Val Jones declares that she has no competing interests
VianaVuvan declares that she has no competing interests
Leanne Bisset declares that she has no competing interests
BillVicenzino declares that he has no competing interests
Funding
This work is not funded and relies on the individuals involved donating their time. Open access
publication fees were funded by the University Hospitals of Derby & Burton NHS Foundation Trust Charity.
Authors contribution
MB and JE share joint rst authorship and were responsible for study concept, design and the writing of
this manuscript
BV was responsible for study concept, design, oversight and the writing of this manuscript
AW, JP, AJ, VV and LB were responsible for study concept, design and the editing of this manuscript
Acknowledgements
N/A
Authors' information
N/A
Abbreviations
COMET Core Outcome Measures in Effectiveness Trials
COS Core Outcome Set
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COS-STAP Core Outcome Set Standardised Protocol
GCP Good Clinical Practice
GDPR General Data Protection Regulation
ICON International Scientic Tendinopathy Symposium Consensus
LET Lateral Elbow Tendinopathy
OMERACT Outcome Measures in Rheumatology
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Figures
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Figure 1
A diagrammatical summary of the method
