Evidence gaps – interventions and methods with evidence uncertainties

SBU collects scientific evidence gaps in the field of healthcare, dental care, social services, occupational health and safety, and functioning and disability, in order to identify areas where new primary research is needed. Our database may serve as a tool for researchers and funding agencies to identify areas and research questions with existing evidence uncertainties. The goal is for future research initiatives to be directed towards projects that will have a positive impact on everyday life for patients, clients, and their families and carers.

What is an evidence gap?

By assessing and summarizing research in a systematic review, we can determine the current level of evidence for the effect of interventions and methods, and we can identify evidence uncertainties.

These uncertainties are called evidence gaps. Evidence gaps are identified when the available studies on an intervention or method are too few, too small, of insufficient quality or present conflicting results. Further practice-based research is then needed to gain knowledge about the effects of the intervention or method.

What is a scientific evidence gap according to SBU’s model and what is needed to fill the gap?

A scientific evidence gap means that there is insufficient evidence to support the overall effect of the intervention or method, i.e. evidence derived from a systematic review. According to SBU’s model, there are three types of evidence gaps, depending on the research needed to fill the gap.

  • A systematic review is needed when we don’t know which studies have been undertaken and we cannot therefore assess the overall effect. Any primary studies need to be identified, assessed and summarized in a systematic review, in order to determine the current level of evidence.
  • More primary studies are needed when a reliable systematic review shows uncertainty about the overall effect. This may be due to lack of studies, or because the studies are at high risk of bias, there are too few studies, the studies are too small or show contradictory results; reliability of the overall effect is very low, for example according to Grading of Recommendations Assessment, Development and Evaluations (GRADE).
  • An updated systematic review is necessary in cases where an earlier review shows that more primary studies are needed and there is reason to believe that there are now more recent studies which might alter the level of evidence on the topic.

For an evidence gap to be entered into SBU’s database, it is a requirement that the intervention or method is used in Sweden or is considered likely to be considered for use in the near future.



Why is it important to identify evidence gaps?

  • Patients, clients, their families and carers as well as professionals gain understanding of the current level of evidence.
  • When choosing or prioritizing which interventions or methods should be used, information about where there are evidence gaps may support decision-making.
  • Research areas where practice-based research or systematic reviews are needed are highlighted.

The Evidence Wheel - activities to increase the benefits of practice-based research

Filling evidence gaps involves the interaction between several stakeholders, and may be seen as an ecosystem in which all parts are dependent on one another.

The process involves assessing the level of evidence of an intervention or method in a systematic review, identifying the evidence gaps, prioritizing what research questions are most important in the field, and implementing practice-based research. In the center of the wheel are patients, clients, families and professionals, who can help identify where research and systematic reviews are needed. These stakeholders are key when prioritizing research issues, designing research projects and implementing the scientific knowledge that is generated.

Where does an evidence gap come from?

The evidence gaps in SBU’s database mainly derive from SBU’s reports, national guidelines from the National Board of Health and Welfare (Socialstyrelsen), reports from the regional HTA organizations and other published systematic overviews. The evidence gaps are gathered from the reports and published in the database on SBU's website.

The contents of SBU’s database on evidence gaps

The database contains information on where research or summarized knowledge is lacking. Note that the database only contains evidence gaps for practice-based research and does not include basic research. The content is steadily changing as new scientific evidence gaps are continuously added to the database, while others are undergoing further research or being removed. During 2021 we started to translate evidence gaps published in SBU’s database into English, focusing on what has been published recently. So far, only a small amount of these evidence gaps have been published on SBU’s website, but the work will continue for the coming years. However, if you are interested in our work with evidence gaps, or if you would like to know if a certain topic has been identified and registered as an evidence gap in our database, you are most welcome to contact us.

In 2021 an inventory of the Swedish version of SBU’s database and The UK Database of Uncertainties about the Effects of Treatments (DUETs) was performed in the area of mental health and published in a report .

Contact persons

  • Marie Österberg (marie.osterberg@sbu.se)
  • Lena Wallgren (lena.wallgren@sbu.se)

How to use SBU’s database on evidence gaps

The database has a search function that makes it possible to find certain areas or categories. Some of the categories specify what ages and genders each evidence gap applies to. There are also categories that specify the source from where the evidence gap was identified, as well as what type of research is needed. It is also possible to search for evidence gaps prioritezed according to the James Lind Alliance process.

The search results can be exported to Excel (open data). This makes the information easier to use and to, for example, list evidence gaps within certain fields or conduct analyses of the contents of the database.

In an accessory database derived from the The UK Database of Uncertainties about the Effects of Treatments (DUETs) , SBU also provides access to evidence gaps identified from the UK.

Evidence gaps from The UK Database of Uncertainties about the Effects of Treatments (DUETs)

There is a former, now archived database, for evidence gaps within medical, dental and social research: The UK Database of Uncertainties about the Effects of Treatments (DUETs). SBU functions as a repository for this database. An Excel file containing evidence gaps identified by DUETs (a total of approximately 11,000 evidence gaps recorded between 2005 and 2016) is accessible via the SBU website. This file also includes references to the scientific reports and systematic reviews in which the evidence gaps were identified.

The evidence gaps registered in the archived database were derived from different types of scientific publications. The main sources include Cochrane, NICE Guidance, and James Lind Alliance Research Priorities. Note that SBU has not critically assessed the underlying reports and systematic reviews.

Parts of the contents in the archived database can also be found in the SBU database. The archived DUETs database is not updated, and the most recently identified evidence gap is from March 2016.

The archived DUETs database can be found here

If you have any questions or identify an evidence gap that may need an update, please contact SBU.

English publications

Practice-based research and scientific evaluation within health care and social services