Prevalence of oral mucosal lesions in population-based studies: A systematic review of the methodological aspects.

OBJECTIVES: To conduct a systematic review of the literature to evaluate the methodological aspects of population-based studies on the prevalence of oral mucosal lesions (OMLs). METHODS: Two reviewers independently conducted a literature search in three databases (PubMed, Web of Science and Scopus) and extracted data using a standardized form. Data on the following characteristics of the included studies were collected: sample size; age of participants; references used to define the diagnostic criteria, training of the examiners, and data collection; type, grouping and characteristics of the lesions; and lesions excluded and measures of agreement between examiners. Data were analysed descriptively, and data synthesis was performed for each of the studies included in the analysis. A quality analysis of the studies was conducted, and the risk of bias was evaluated. RESULTS: A total of 29 studies were included in the analysis. Most of the published studies on the prevalence of OMLs were performed in Asian countries. The sample sizes ranged from 255 to 39 206. The World Health Organization guidelines were followed by most of the studies, in terms of design, examiner training and data collection. Approximately 25% of the studies did not determine inter-examiner reliability. Moreover, almost half of the studies included did not report the response rate nor did they present the results with the appropriate confidence intervals. CONCLUSIONS: Several important points need to be improved in population-based studies focusing on the prevalence of OMLs. In particular, these studies should adequately report the response rate and findings, and to a lesser extent, the diagnostic criteria and training of the examiners. We encourage more research in this field and reinforce the importance of standardized studies to facilitate the comparison of different findings. PROSPERO registration number: CRD42018099386.