Diagnostic Delay and Clinical Follow-Up Across Oral Lichen Planus Phenotypes: A Retrospective Cohort Study

Background: Oral lichen planus is a chronic oral potentially malignant disorder requiring timely diagnosis and long-term follow-up, yet its diagnostic pathway remains poorly characterised. This study assessed diagnostic and follow-up intervals in patients with oral lichen planus and explored associated clinical and healthcare-related factors. Methods: This retrospective cohort study included 199 patients with clinically and histopathologically confirmed oral lichen planus managed at the Oral Medicine Unit of the University of Murcia. Diagnostic time points were defined using an adapted Aarhus framework. Patient, primary care, specialist diagnostic and total intervals were analysed using multivariable quasi-Poisson regression. Loss to follow-up was assessed using Cox regression. Results: Older age was associated with longer patient, primary care and total intervals. Women had a shorter patient interval than men (IRR = 0.44; 95% CI: 0.21–0.91; p = 0.03), but a longer primary care interval (IRR = 3.09; 95% CI: 1.12–10.2; p = 0.04). Compared with erosive oral lichen planus, mixed and reticular forms showed shorter primary care intervals and shorter specialist diagnostic intervals, with IRRs ranging from 0.21 to 0.36 (all p < 0.01). Daily alcohol consumption was associated with the longest total interval. Older age was associated with a higher risk of loss to follow-up (HR = 1.02; 95% CI: 1.00–1.04; p = 0.01), whereas non-pharmacological treatment was associated with a lower hazard of loss to follow-up (HR = 0.31; 95% CI: 0.16–0.60; p < 0.001). Conclusions: Diagnostic delay in oral lichen planus is multifactorial and appears to depend on patient characteristics, clinical presentation and healthcare pathway factors. Improved recognition of erosive disease, clearer referral criteria and structured follow-up strategies may enhance care continuity.