Sir, we would like to inform the readers of an update to the PRISMA 2009 statement,1 which was referenced in the article submitted by Alkadhimi et al. in January 2021 and accepted for publication in April 2021.2The PRISMA 2020 statement3 replaces the 2009 statement1 and was published in March 2021. It includes new reporting guidance for systematic reviews that reflects advances in methods to identify, select, appraise and synthesise studies.

The updated statement consists of an improved 27-item checklist, the PRISMA 2020 abstract checklist and revised flow diagrams for original and updated reviews. This letter aims to inform on the most noteworthy changes, including the need to include full search strategies for all databases, where previously the recommendation advised at least one database. In addition, under study selection, there is now an emphasis on detailing the reviewers involved. This includes the total number of reviewers and if any automated tools were used.

Under 'Data items' in the new checklist, the addition of a sub-item aims to clarify how outcomes are defined, the methods utilised to select results and how this was carried out. 'Synthesis of results', under the methods section, is now broken into six sub-items to define the recommendations for reporting the eligibility, preparation, display, synthesis, exploration of heterogeneity and sensitivity analyses utilised during gathering and collating data. The 'Synthesis of results' within the results section has also been broken down to allow for more depth on the risk of bias, causes of heterogeneity and the use of sensitivity analyses.

The addition of reporting the certainty/confidence of evidence and its implications also allows for clinicians to understand how the results should be translated into policy and practice. Competing interests are now recommended to be reported for transparency of the results. This is along with whether the data, analytical code, or any other aspects of the collection and interpretation are publicly available and if so, where they can be accessed.

The flow diagrams have also changed to reflect the checklist and simplify understanding of the process. The previous four-phased flow diagram on study inclusion has now been updated to three, with removal of 'eligibility' and retention of 'identification', 'screening' and 'included'.

The PRISMA 2020 statement aims to encourage standardisation and reproducibility for reporting outcomes. Reporting and sharing findings through this method will allow for work carried out to be shared, reducing duplication and meaning further research can be conducted. This update ultimately aims to increase our ability to facilitate the highest standard of evidence-based care for our patients.