Background Oral lichen planus (OLP) is a chronic inflammatory condition known to adversely impact patient quality of life and is associated with an increased risk of cancer. The diverse clinical presentation and poor knowledge of clinical factors that determine the course of disease are amongst the main challenges that hinder effective and personalised treatment for OLP patients.

Aim This study aimed to systematically identify clinical predictors of disease severity in OLP patients.

Methods A cohort of patients with histologically confirmed OLP (n=87) was recruited in a cross-sectional and single site study. A comprehensive assessment of clinical characteristics, medical and social history, haematological parameters, vitamin D levels, and Perceived Stress Scale (PSS-10) was carried out. Hierarchical linear regression identified the predictive value of clinical factors to OLP disease severity measured by the Oral Disease Severity Score (ODSS) and the Reticular/hyperkeratotic, Erosive/erythematous, Ulcerative (REU) scoring system.

Results Our results revealed that extraoral lichen planus and insufficient vitamin D levels were significant predictors of both overall and gingival disease severity of OLP. Specifically, patients with lichen planus affecting the skin or other mucosal sites had a 5.9-unit higher OLP severity score (β=5.998, 95% CI=.888-11.107, p=.022) than those without extraoral involvement as measured by ODSS. Interestingly, patients with insufficient vitamin D levels exhibited 5.3-unit increase in OLP severity (β=5.344, 95% CI =.914-9.774, p=.019) compared to those with adequate vitamin D levels. The presence of dental plaque induced gingivitis (β=4.467, 95% CI =.600-8.333, p=.024), was found to be a significant factor affecting gingival disease severity.

Conclusion Our study revealed the importance of adequate vitamin D levels in OLP patients and suggests embedding vitamin D pre-treatment screening to optimise management of OLP. Future research should focus on elucidating the biological mechanisms underlying the protective effects of vitamin D in OLP.

The authors have declared no competing interest.

No external funding was received.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical approval was obtained from the West Midlands-Black Country Research Ethics Committee (Reference number: 21/WM/0247).

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All data produced in the present study are available upon reasonable request to the authors