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1.19

Spot the needle

# Systematic searching

We saw in the last step that different sources of information are more authoritative than others. When an important decision needs to be made, for example what health care treatment is most effective for a specific condition, that decision should be informed by the best available research evidence. As most individuals don’t have the time to find, obtain and then critically appraise all the research available to answer their questions, systematic reviews are often their best source of evidence.

Systematic reviews aim to identify, critically evaluate and integrate the findings of all relevant, high-quality individual studies addressing a specific research question.

So what makes a systematic review a reliable enough source of research evidence that such conclusions can be safely drawn and made? High-quality systematic reviews are not only systematic in approach; their methodology is transparent, pre-specified, objective and reproducible. A good systematic review will clearly state its objectives and the eligibility criteria for the studies it will include. It will aim to locate all studies which address a particular research question and it will critically assess the validity of the findings of each study (e.g. the risk of bias). It will then go on to synthesise the findings from individual studies in an unbiased manner, and present a summary of what can reliably be said on the basis of these studies. This open and explicit approach allows readers of the systematic review to assess the author’s assumptions, methods, evidence and conclusions. As such they can provide reliable results.

### What is involved in systematic searching?

Systematic reviews require the development of a complex search strategy, often built up in stages, which considers both specificity (limited and relevant – connected using the search operator “and”) and sensitivity (terminology and synonyms – connected using the search operator “or”). Searches can be limited to specific fields in the database (e.g. title (“ti” in the example below) or abstract (“ab”)). Search strategies for systematic reviews include controlled language (terms from database thesauri and subject headings – denoted by a “/” below) as well as keywords. This ensures the search captures all relevant records on a subject.

### An example search strategy

1. Hip Joint/

2. Hip Prosthesis/

3. Acetabulum/

4. hip replacement$.ti,ab. 5. total-hip replacement$.ti,ab.

6. total joint replacement$.ti,ab. 7. hip surgery.ti,ab. 8. hip operation$.ti,ab.

9. (hip adj3 prosthe$).ti,ab. 10. (hip adj3 arthroplasty).ti,ab. 11. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 12. exp Bacterial Infections/ 13. exp Postoperative Complications/ 14. Surgical Wound Infection/ 15. Prosthesis-Related Infections/ 16. Sepsis/ 17. exp Anti-Infective Agents/ 18. exp Infection Control/ 19. exp Antibiotics/ 20. Antibiotic Prophylaxis/ 21. ((bacteri$ or wound$) adj2 (infect$ or contamin$)).ti,ab. 22. sepsis.ti,ab. 23. antibiotic$.ti,ab.

24. antimicrobial$.ti,ab. 25. anti-microbial$.ti,ab.

26. (anti$adj infect$).ti,ab.

27. ultraclean.ti,ab.

28. hypersterile.ti,ab.

29. or/12-28 30 11 and 29

Centre for Reviews and Dissemination, University of York, 2008

As you can see this is much more complex than the kind of searches we tend to do on a daily basis to find information, but adopting some of these techniques such as searching for alternate terms and combining terms can improve the relevance of the results we retrieve. For some useful hints and tips regarding these techniques, take a look at our Digital Skills Guides.