Background: Systematic reviews, considered the gold standard for the assessment of scientific evidence, may present conflicting findings for the same clinical issue, and such dissent may be justified by the forms of elaboration of the electronic search strategy. This paper aims to validate a search strategy to identify randomized clinical trials related to periodontitis. A gold standard reference set was developed to validate the identified clinical trials using the relative recall method. The choice of periodontitis is due to the fact that this disease has a high prevalence among chronic non-communicable diseases, is considered the second most common oral disease in the world, is associated with several health problems, such as cardiovascular diseases and diabetes, and, principally, has not been investigated sufficiently to prevent possible damages resulting from it.

Methods: A validation study was developed in MEDLINE/PubMed. In Stage 1, a methodological filter recommended by the Cochrane Collaboration to identify randomized clinical trials was applied. Stage 2 identified articles related only to periodontitis (gold standard reference set) from among the articles retrieved using the eligibility criteria. In Stage 3, a search statement for the retrieval of periodontitis-related articles was elaborated by experts. Stage 4 defined the proposed search strategy comprising of the combination of the search statement developed with the aforementioned methodological filter and subsequent application in MEDLINE/PubMed. The obtained data were analyzed using the set of articles identified in Stage 2, as the gold standard reference set. The following performance values were calculated - sensitivity, specificity, accuracy, and number needed to read - with their respective 95% confidence interval (95%CI).

Results: The search strategy under evaluation compared to the gold-standard showed a sensitivity of 93.2% (_95%CI, 83.8-97.3), specificity of 99.9% (_95%CI 99.8-99.9), and a precision of 77.5% (_95%CI, 66.48-85.63). In addition, the number needed to read was 1.3.

Conclusion: According to the proposed methodological approach, the search strategy under evaluation performed well in the identification of randomized clinical trials related to periodontitis.