Subject headings take time to be developed so if your research includes a new concept there may not be a relevant subject heading. There isn't a subject heading for every topic which is why it's important to include a comprehensive keyword search.
There is no ideal number of results to get from a systematic search and it will largely depend on your research question or topic. If you are trying to gather information on a treatment plan that was piloted in 2023, there will obviously be far fewer published resources than those focused on an established treatment plan that has been standard practice for decades.
If your systematic search has generated too many results or a large number of irrelevant results, try to be more specific. Try the following:
- Use more specific search terms, e.g. 'ischaemic stroke' will retrieve more relevant, focused results than just 'stroke'
- Add a concept (this could include one you had previously excluded, study design or time frame)
- Try using the database filters (publication date, age of participants, study design, etc.). Note: database filters are not automatically applied to resources when they are added to a database so this may exclude some relevant results.
There can be a number of things to consider if you are not able to find enough relevant resources as part of your research. Consider the following:
- You may need to broaden your search terms. E.g. rehabilitation rather than telerehabilitation
- Try removing a concept such as Outcome if you're using PICO
- If you have used any database filters, remove them
- If you can locate a systematic review, check the abstract to see what terminology is being used and compare it to your own strategy. You may be able add new terms to your search.
- Try your search in another database, remember each database has access to different resources