Do authors of systematic reviews of epidemiological observational studies assess the methodologies of the included primary studies? An empirical examination of methodological tool use in the literature.

Background: The procedures used to assess the methodological quality and risk of bias (RoB) of systematic reviews of observational dental studies have not been investigated. The purpose of this research was to examine the way that authors of systematic reviews of epidemiological observational studies published in dentistry conducted the methodological assessment of those primary studies. In the present article, we aimed to assess the characteristics and the level of reporting of tools used to assess the methodologies of these reviews.

Methods: We searched Scopus and the Web of Science from their inceptions to June 2023 for systematic reviews with meta-analyses of observational studies published in dentistry. Document selection and data extraction were performed in duplicate and independently by two authors. In a random sample of 10% of the systematic reviews, there was an agreement of more than 80% between the reviewers; data selection and extraction were conducted in the remaining 90% of the sample by one author. Data on the article and systematic review characteristics were extracted and recorded for descriptive reporting.

Results: The search in the two databases resulted in the inclusion of 3,214 potential documents. After the elimination of duplicates and the application of the eligibility criteria, a total of 399 systematic reviews were identified and included. A total of 368 systematic reviews reported a methodological tool, of which 102 used the Newcastle-Ottawa scale. Additionally, 76 systematic reviews stated the use of a modified methodological tool. Information about the approach of assessing the methodological quality or RoB of primary studies but reporting no tool or tool name occurred in 25 reviews.

Conclusions: The majority of authors of systematic reviews of epidemiological observational studies published in dentistry reported the tools used to assess the methodological quality or RoB of the included primary studies. Modifying existing tools to meet the individual characteristics of various studies should be considered.