Prevalence and incidence of comorbid diseases and mortality risk associated with lichen planopilaris: a Korean nationwide population-based study

Background: Various comorbid diseases have been reported in patients with lichen planopilaris (LPP); however, data regarding the risks of incident diseases and mortality are lacking.

Objectives: To investigate the risks of incident diseases and mortality associated with LPP.

Methods: This was a retrospective nationwide population-based study, using data from the National Health Insurance Service Database of Korea from 2002 to 2019. Patients aged ≥ 18 years with three or more documented medical visits for LPP were included. The adjusted hazard ratios (aHRs) for incident disease outcomes and mortality were compared with 1 : 20 age-, sex-, insurance type- and income-level-matched controls.

Results: In total, 2026 patients with LPP and 40 520 controls were analysed. The risks of incident systemic lupus erythematosus [aHR 1.91, 95% confidence interval (CI) 1.21-3.03], psoriasis (aHR 3.42, 95% CI 2.83-4.14), rheumatoid arthritis (aHR 1.39, 95% CI 1.19-1.63), lichen planus (aHR, 10.07, 95% CI 7.17-14.15), atopic dermatitis (aHR 2.15, 95% CI 1.90-2.44), allergic rhinitis (aHR 1.29, 95% CI 1.13-1.49), thyroid diseases (hyperthyroidism: aHR 1.42, 95% CI 1.14-1.77, hypothyroidism aHR 1.19 95% CI 1.01-1.41, and thyroiditis: aHR, 1.35, 95% CI 1.08-1.69), nonmelanoma skin cancer (aHR 2.33, 95% CI 1.00-5.44) and vitamin D deficiency (aHR 1.23, 95% CI 1.03-1.47) were higher in patients with LPP. Patients with LPP had a higher mortality rate than controls (aHR 1.30, 95% CI 1.04-1.61), although the risk was not significant after adjusting for comorbidities (aHR 1.08, 95% CI 0.87-1.34).

Conclusions: Patients with LPP had a higher risk of various diseases following LPP diagnosis. Close follow-up is needed to optimize comprehensive patient care.