5. How do I manage my search results?
5.1. Additional reading: Not enough evidence?
6.1 Additional reading: Not enough evidence?
It is not unusual for a veterinary (S)PICO search to retrieve no evidence, but there are a number of constructive things you can do if this happens.
If your database searching finds zero publications, consider why this might be and what you can do next.
There are four main reasons why you might get zero hits.
1. The evidence doesn’t exist
The body of veterinary literature is relatively small compared with that for human medicine, so it may be that there is just no published evidence out there that answers your question.
If you find that there is no evidence, report and publish this.
- It helps identify gaps in the evidence base
- It helps focus new research funding and effort where it’s needed
- It prevents duplicated effort (i.e. saves someone else wasting time repeating the search)
You will find many examples of evidence syntheses that report zero hits – this is not a sign of failure!
While it may be tempting to refine our question in light of zero hits, or abandon publishing an evidence summary, we should guard against bias and openly report areas where evidence is lacking.
Just because there is no published evidence for treatments does not mean they do not work. When literature searches reveal gaps in available evidence this can be seen as an opportunity to identify new areas for publishing research, but can also be a reminder that formally published studies are only one part of EBVM, with the preferences of patients/owners and the knowledge and experience of vets also key factors in decision-making.
2. The evidence exists, but can’t be found via bibliographic databases
Remember, the bibliographic databases generally only list formal publications, and will not always retrieve grey literature or evidence that has not been published.
For vets this is a particular issue, as much evidence may be tucked away in practice clinical records, rather than scientific publications.
Vets need to be open to using other sources/methods for finding published evidence:
- Grey literature/unpublished data/online sources
- Case records we may have access to locally
- Using social media/social networks to locate others who know of relevant evidence
3. The evidence does exist in the databases, but we’re not finding it
It might be that our search strategy is not effective for retrieving evidence from the databases. Things to consider:
- Get your search strategy checked by a colleague or librarian, to see if it has errors in it or if it can be improved.
- Avoid 'over-specification' where your query is too narrow and so yields few or no results. Consider dropping an element of your (S)PICO from the database search:
- SPECIES – do you really need to include this in your search?
- PROBLEM – are there broader terms you could use?
- INTERVENTION – there won’t always be studies that directly compare your intervention with your comparison, so try searching on just one of them
- OUTCOME – rarely included in veterinary searches, as the outcome terms are often very broad, with many synonyms, so can cause you to miss relevant results.
- Try to improve your database search skills with training.
4. The evidence exists but you can’t get access to it
Refer to the earlier advice on accessing evidence.