Association of oral lichen planus and psoriasis: a case-control study.

Objective: The aim of the present study was to investigate whether psoriasis disease constitutes a risk factor for OLP, by assessing the prevalance of psoriasis in a test group with OLP and the control group without.

Method and materials: A cohort of consecutive patients diagnosed clinically and histologically with OLP between 2014 and 2022 was analyzed. The results were contrasted with those obtained in control series matched for age and sex. The correlations between OLP and sex, age, tobacco, alcohol consumption, and psoriasis were assessed using Pearson chi-square test. Multivariate regression analysis was performed to evaluate the association between psoriasis and OLP. For the assessment of the quality of the statistical models, the Akaike information criterion was used.

Results: The study involved 1,016 patients; 738 women (72.6%) and 278 men (27.4%). The average age was 59.38 ± 12.55 years. Of 508 patients with OLP, 16 (3.15%) had comorbid psoriasis, and this was 5 (0.98%) in the control group. Age, sex, smoking, and alcohol habits were not predictive variables in the relationship between psoriasis and OLP in these patients. There were statistically significant differences in relation to the number of locations, with greater extension in patients with OLP and psoriasis (P = .002). According to the multivariate analysis, the odds ratio of OLP for psoriasis was 3.13 (95% CI 1.20-9.68).

Conclusions: This is the first study showing the potential association between psoriasis and OLP, and the results should be considered to improve knowledge of comorbidity of OLP. Based on the results, it is recommended that clinicians collect data regarding history of psoriasis in patients with OLP, and consider possible multiple intraoral locations.