Objective: To examine all studies reporting prevalences of oral lichen planus (OLP) for epidemiological validity and to extract prevalence data from the valid papers.
Design: Computer based literature searches were carried out using the MeSH headings 'lichen planus, oral and (prevalence or incidence)' and were supplemented by manual searching.
Main outcome measures: Each paper was examined for five criteria: clinic-based or population study, adequate demographic description (by sex and age group) of the population, adequate demographic description of the sample (if the population was sampled), adequate demographic description of the OLP cases identified, and histological confirmation of the clinical diagnosis.
Results: Forty-five relevant papers were identified, 21 clinic-based and 24 population studies. All but one of the population studies was deficient. One study, while having some defects, was probably sufficiently valid to permit the findings to be regarded as useful. An overall age-standardized prevalence of 1.27% (0.96% in men and 1.57% in women) can be calculated from this study.
Conclusions: There appears to be only one usable prevalence study of OLP. Other large-scale studies are required in other populations. Such studies need to distinguish between OLP and lichenoid reactions.