Global Prevalence and Incidence Estimates of Oral Lichen Planus: A Systematic Review and Meta-analysis.

Importance: Integrated information on the global prevalence and incidence of oral lichen planus (OLP) is lacking. Objective: To examine the global prevalence and incidence of OLP in a systematic review and meta-analysis. Data Sources: A systematic review of population-based studies and clinic-based studies reporting the prevalence and incidence of OLP was performed using 3 electronic medical databases (Cochrane Database of Systematic Reviews, Embase, and MEDLINE) from their inception to March 2019. The search terms included "(lichen planus or LP) and (prevalence or incidence or epidemiology)." No language restriction was applied. Study Selection: Observational descriptive studies investigating the prevalence and incidence of OLP were included. Data Extraction and Synthesis: Data were extracted by continent, sex, and other characteristics. The risk of bias was assessed by the Joanna Briggs Institute Critical Appraisal Instrument for Studies Reporting Prevalence Data using random-effects models to synthesize available evidence. Main Outcomes and Measures: The primary outcome was the prevalence (with 95% CIs) of OLP among the overall population and among subgroups. Between-study heterogeneity was assessed using the I2 statistic. Results: Among 46 studies, the overall pooled estimated prevalence of OLP was 0.89% (95% CI, 0.38%-2.05%) among the general population (n = 462 993) and 0.98% (95% CI, 0.67%-1.43%) among clinical patients (n = 191 963). Among the 15 population-based studies, the prevalence of OLP was 0.57% (95% CI, 0.15%-2.18%) in Asia, 1.68% (95% CI, 1.09%-2.58%) in Europe, and 1.39% (95% CI, 0.58%-3.28%) in South America. Among the 31 clinic-based studies, the prevalence was 1.43% (95% CI, 1.12%-1.83%) in Africa, 0.87% (95% CI, 0.61%-1.25%) in Asia, 1.03% (95% CI, 0.51%-2.09%) in Europe, 0.11% (95% CI, 0.07%-0.16%) in North America, and 3.18% (95% CI, 0.97%-9.95%) in South America. The pooled prevalence of OLP by sex was 1.55% (95% CI, 0.83%-2.89%) for women and 1.11% (95% CI, 0.57%-2.14%) for men in the population-based studies and 1.69% (95% CI, 1.05%-2.70%) for women and 1.09% (95% CI, 0.67%-1.77%) for men in the clinic-based studies. In 5 clinic-based studies providing the age distribution of patients with OLP, the prevalence by age was 0.62% (95% CI, 0.33%-1.13%) among patients younger than 40 years and 1.90% (95% CI, 1.16%-3.10%) among patients 40 years and older. Conclusions and Relevance: This study identified the global prevalence and incidence of OLP in terms of its spatial, temporal, and population distribution. The overall estimated pooled prevalence of OLP was 0.89% among the general population and 0.98% among clinical patients. A higher prevalence of OLP was found in non-Asian countries, among women, and among people 40 years and older. The findings should be considered with caution because of the high heterogeneity of the included studies.