Article Text

Identifying classification systems regarding vascular access for haemodialysis: protocol for a scoping review
  1. Katerina Lawrie1,2,
  2. Jan Bafrnec1,2,
  3. Stephen O’Neill3,4,
  4. Michael Corr3,4,
  5. Petr Waldauf5,
  6. Peter Balaz1,2
  1. 1Division of Vascular Surgery, Third Faculty of Medicine, Charles University, University Hospital Kralovske Vinohrady, Prague, Czech Republic
  2. 2Cardiocenter, Third Faculty of Medicine, Charles University, University Hospital Kralovske Vinohrady, Prague, Czech Republic
  3. 3Department of Transplant Surgery and Regional Nephrology Unit, Belfast City Hospital, Belfast, UK
  4. 4Centre for Public Health, Queen's University Belfast, Belfast, UK
  5. 5Anaesthesiology and Resuscitation, Third Faculty of Medicine, Charles University, University Hospital Kralovske Vinohrady, Prague, Czech Republic
  1. Correspondence to Katerina Lawrie; katerina.lawrie{at}


Introduction Classifications are important clinical tools that enable data arrangement, patient categorisation and comparative research. The care of patients with end-stage renal disease who have vascular access requires collaboration of several specialists. In such a field, where several different specialties overlap, strong evidence and well-grounded recommendations for good practice are essential. In this protocol, we aim to search the literature to identify classification systems regarding vascular access for haemodialysis. This protocol serves as a pragmatic tool for setting a systematic approach using scoping review methodology. It also aims to make the study transparent and avoid potential duplication.

Methods and analysis We will follow the Joanna Briggs Institute methodology for the conduct of scoping reviews during the course of the proposed review. Scopus, Web of Science, PubMed, Google Scholar and the registry will be searched by two researchers. Titles and abstracts will be screened and articles featuring classifications regarding vascular access for haemodialysis will be eligible for full-text analysis. There will be no age, sex or race limitation for the study populations. The title and abstract (if abstract available) must be in English but there will be no language restrictions for full-text review. Databases will be searched from inception to the date of search. All patients indicated for creation or placement of vascular access will be eligible, as well as patients with already existing vascular access. Classifications regarding preprocedural assessment, vascular access insertion or creation, complications and their management will be included in the study. Classifications regarding peritoneal dialysis will not be eligible. A comprehensive summary of the available evidence will be presented.

Ethics and dissemination The protocol and the review are exempt from ethical approval as there is no direct patient involvement and the review will summarise data from already published literature. The final article will be submitted to a peer-reviewed scientific journal.

  • dialysis
  • protocols & guidelines
  • chronic renal failure
  • end stage renal failure
  • vascular surgery

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Strengths and limitations of this study

  • Our review follows the methodological framework of Joanna Briggs Institute.

  • Scopus, Web of Science, PubMed, Google Scholar and the registry will be used for the literature search, and grey literature will also be eligible.

  • There will be no language restrictions for full-text review.

  • The review will not include classifications regarding peritoneal dialysis.


Classification systems form basic pillars for data collection, compilation and categorisation. Methodical organisation of a large amount of information into well-defined categories with coherent structure allows transparent data identification and is essential for statistical analysis.1 A large amount of unorganised data is often impossible to evaluate and process. All medical fields contain an infinite amount of information that is constantly increasing. Classifications help to systematically arrange the data and enable easy and effective processing. Any scores should be simple, logical and easily applicable. In medicine, ideally, they should reflect outcomes and serve as predictive parameters.2 Such organised data sets are effectively analysed and serve clinical and scientific purposes.3

Chronic kidney disease and end-stage renal disease are increasingly common. A total of 850 million people were estimated to be living with chronic kidney disease in 2017.4 And the world-wide dialysis population is rising.5–7 Haemodialysis is the most common dialysis modality, accounting for approximately 89% of all dialysis and 69% of all renal replacement therapy.8 Patients who are dependent on haemodialysis require vascular access, which can either be a dialysis catheter placed into central vein, or an arteriovenous access created typically by a vascular access surgeon. Care of the patients with vascular access is complex and demands a multidisciplinary approach. Variability in classifying dialysis access makes interprofessional communication and research in this developing field difficult. Well-designed classification systems could improve communication on a professional level, enhance patient management and quicken scientific progress.

Methods and analysis

Scoping review methodology

Our aim is to explore all the available classification systems in the literature to describe and categorise vascular accesses used in haemodialysis populations. To our knowledge, there is no review, summary or published protocol regarding this topic. We selected a scoping review as the appropriate approach to use. A methodological framework of Joanna Briggs Institute9 for conducting scoping reviews has been used in the design of this protocol and will guide the future scoping review. The protocol and the scoping review adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR).10


To clarify and map what classification systems regarding vascular access for haemodialysis are published in the current literature and to present a comprehensive summary

Eligibility criteria


The study population is limited to patients who are assessed for the creation of arteriovenous access (AVA) or have existing vascular access (used or unused). Patients with current or previous dialysis catheter insertion will also be included. Studies will be included from all populations independent of age, sex or race.


All articles that contain classification systems regarding vascular access for haemodialysis are eligible. Classification systems regarding preprocedural assessment, AVA creation, dialysis catheter placement, postprocedural care and follow-up, AVA-related perioperative, postoperative, central venous dialysis catheter placement complications and their management will be included. Potential studies for inclusion must contain the terms ‘classification’ or ‘classification system’ or ‘score’ in their description and the classification systems must present an idea of grouping or organising vascular access-related information into groups, categories and/or subcategories. The number of created categories is not relevant.


All study methodological types will be eligible. The title and abstract (if abstract available) must be in English, however there will be no language limitation in assessing full-text articles.

Articles where full texts cannot be obtained and those with non-English titles or abstracts will be excluded. Publications focused on definitions and nomenclature concerning vascular access for dialysis that do not explicitly introduce a classification system will not be included. Classifications regarding peritoneal catheters for dialysis will also not be included.

Search strategy

Information sources

A search of Scopus, Web of Science, PubMed, Google Scholar and the registry will be performed. Grey literature found via Google Scholar will also be eligible for inclusion and references included studies will be evaluated for further studies eligible articles.

Date range

The search will be from database inception to the date when formal search is initiated for the review. The date of the search is not currently known as it will be assessed after publication of this protocol.

Search terms

The search terms will be combinations of the following: classification, classification system, score, categorisation, arteriovenous fistula, arteriovenous shunt, arteriovenous access arteriovenous graft, dialysis catheter, vascular access, permcath, central venous catheter, dialysis, haemodialysis and renal replacement therapy. A detailed search strategy is presented in the online supplemental material.

Study records and data items

Data management

All the retrieved articles will be downloaded and organised into arranged datasheets (table 1). Duplicates will be identified and eliminated using software R v.4.2.2. The full texts of the eligible articles will be uploaded into Mendeley Reference Management Software.

Table 1

Datasheet arrangement for retrieved articles

Selection process

Two independent reviewers (KL and JB) will perform the database searches. After the elimination of duplicates, the titles and the abstracts will be screened for eligibility. The articles assessed as eligible will undergo full-text analysis. If discrepancies between the two researchers occur, a third researcher (PB or SO) will be consulted. All efforts will be made to obtain full texts of the selected articles. This will include search of the web, help from the librarian of Charles University in Prague or contacting the author directly if necessary. A translator will be employed if translations of full texts are required. A flowchart of the selection process (PRISMA 2020 flow diagram) will be used in reporting the results of the study.11

Data collection process

A charting form will be used for the collection of relevant data from the included studies by two independent researchers (KL and JB) and will be saved in electronic form. Data collection form can be seen in table 2.

Table 2

Charting form for data collection

Data analysis

To critically evaluate the classifications, each classification system will be assessed by using the individual classification systems appraisal by Buchbinder et al,12 which has been used previously by other authors for the evaluation of classification systems.13 14 This system includes items covering purpose, content validity, face validity, feasibility, construct validity, reliability and generalisability.12

The scoring system will be applied by four independent reviewers (KL, JB, MC and PB). The answers to the questions will be scored by following rules: ‘Yes’ = 1, ‘Partial’ = 0.5, ‘No’, ‘Don’t know’ and ‘Not applicable’ = 0. The exception for scoring is in the question: ‘Are special skills, tools or training required?’ (fourth category), where ‘No’ = 1 point and ‘Yes’ = 0.

The overall scores and weighted scores will be calculated, where an overall score ≤3 indicates low quality, a score of 3–5 as moderate and ≥5 as good quality respectively.

To evaluate the reliability of the appraisal system, the inter-rater reliability between the reviewers will be assessed by using Cohen’s kappa.

Data presentation

The data will be presented in a summary table that will include the title of the classification, type of classification system, author’s name, year of publication, type of article, language, purpose of the classification system, method of development (if available), method of validation (if available), citation in guidelines (number of citations) and Buchbinder’s critical appraisal score with Cohen’s kappa score.

Time frame

The whole process of the literature search, data extraction, evaluation of the classification system, writing the scoping review and submitting the review to scientific journal is planned for years 2022–2023.

Patient and public involvement


Ethics and dissemination

The proposed scoping review aims to give the reader comprehensive information about the current state of classification systems in the vascular access field. As the review will synthesise the information from already published literature and the patients are not directly involved, the study is spared of ethical committee approval.

We would like to present a clear summary of known and less known classifications, their qualitative appraisal and their use for evidence-based medicine and clinical practice. We also aim to show gaps and possibilities for improvements via a thorough understanding of the current literature.

The extracted data will be summarised and presented in the scoping review will meet the criteria of the PRISMA-ScR statement checklist10 and submitted for publication in a scientific journal.

Ethics statements

Patient consent for publication


Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.


  • Contributors The protocol was designed by KL, SO, MC and PW. Draft of the manuscript was written and revised by KL, MC and SO. Review and a final approval of the manuscript was done by all authors: KL, JB, SO, MC, PW and PB.

  • Funding The project is supported by the Charles University Research programme “Cooperatio – Cardiovascular Science” and the Belfast Health and Social Care Trust Charitable Funds PA Programme.

  • Competing interests PB is the lead author and SO and KL are coauthors of the AVAS (Arterio Venous Access Stage) classification system.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.