Study protocol for Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID)
Authors: Viecelli Andrea K. , Teixeira-Pinto Armando , Valks Andrea , Baer Richard , Cherian Roy , Cippà Pietro E. , Craig Jonathan C. , DeSilva Ranil , Jaure Allison , Johnson David W. , Kiriwandeniya Charani , Kopperschmidt Pascal , Liu Wen-J , Lee Timmy , Lok Charmaine , Madhan Krishan , Mallard Alistair R. , Oliver Veronica , Polkinghorne Kevan R. , Quinn Rob R. , Reidlinger Donna , Roberts Matthew , Sautenet Bénédicte , Hooi Lai Seong , Smith Rob , Snoeijs Maarten , Tordoir Jan , Vachharajani Tushar J. , Vanholder Raymond , Vergara Liza A. , Wilkie Martin , Yang Bing , Yuo Theodore H. , Zou Li , Hawley Carmel M. ,   on behalf of the VALID Investigator Team, Robison Laura , Welch Alyssa , Badve Sunil V. , Boudville Neil , Campbell Katrina , Cho Yeoungjee , Collins Michael , Fahim Magid A. , Jardine Meg , Du Toit Dianne , Mayne Michelle , Stevenson Kim , James Rachel , Vu Quynh , Allen Karyn , Glancy Leanne , Kumbikkal Jijo , Burton Sharan , Gordon Lisa , McCarthy Kylee , Forrester Cathy , Lima Sally , Bourgault Olivier , Drouault Claire , Teasdale Fanny , Jiun Liu Wen , Abidin Jamian , Kiang Cheng Jin , Leng Lee Soon , Yusoff Yuana Mohd , Ciochina Adriana , van Loon Magda , Ophelders Ronald , Vleugels Marie-Jose , Ferrari Paolo , Brodeur Marie-Ève , Giunzioni Davide , Molfese Christine Bressan , Blackwell Christopher , Dunn Louese , Gillis Laura , Gray Barry , Jenkins Sarah 
Published: November 2022

Abstract
Background
A functioning vascular access (VA) is crucial to providing adequate hemodialysis (HD) and considered a critically important outcome by patients and healthcare professionals. A validated, patient-important outcome measure for VA function that can be easily measured in research and practice to harvest reliable and relevant evidence for informing patient-centered HD care is lacking. Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID) aims to assess the accuracy and feasibility of measuring a core outcome for VA function established by the international Standardized Outcomes in Nephrology (SONG) initiative.

Methods
VALID is a prospective, multi-center, multinational validation study that will assess the accuracy and feasibility of measuring VA function, defined as the need for interventions to enable and maintain the use of a VA for HD.
The primary objective is to determine whether VA function can be measured accurately by clinical staff as part of routine clinical practice (Assessor 1) compared to the reference standard of documented VA procedures collected by a VA expert (Assessor 2) during a 6-month follow-up period. Secondary outcomes include feasibility and acceptability of measuring VA function and the time to, rate of, and type of VA interventions.
An estimated 612 participants will be recruited from approximately 10 dialysis units of different size, type (home-, in-center and satellite), governance (private versus public), and location (rural versus urban) across Australia, Canada, Europe, and Malaysia.
Validity will be measured by the sensitivity and specificity of the data acquisition process. The sensitivity corresponds to the proportion of correctly identified interventions by Assessor 1, among the interventions identified by Assessor 2 (reference standard). The feasibility of measuring VA function will be assessed by the average data collection time, data completeness, feasibility questionnaires and semi-structured interviews on key feasibility aspects with the assessors.

Discussion
Accuracy, acceptability, and feasibility of measuring VA function as part of routine clinical practice are required to facilitate global implementation of this core outcome across all HD trials. Global use of a standardized, patient-centered outcome measure for VA function in HD research will enhance the consistency and relevance of trial evidence to guide patient-centered care.

Trial registration
Clinicaltrials.gov: NCT03969225. Registered on 31st May 2019.