Repurposing the composite assessment of index lesion severity scoring system in cutaneous lichen planus

Current validated lichen planus (LP) scoring systems are complicated and optimized for generalized, multi-site disease. There is a need for a validated, simple lesional assessment in LP. Herein, we repurpose and optimize the modified Composite Assessment of Index Lesion Severity (mCAILS) for LP and to validate the optimized lichen planus CAILS (lpCAILS). In this study, cutaneous LP lesions for disease activity and treatment response were prospectively assessed at two single-center, single-arm, open-label clinical trials at Mayo Clinic, Arizona with lpCAILS. Twelve index lesions from the topical ruxolitinib trial in 2018-2021 were used for the development and optimization of lpCAILS, with subsequent internal validation. After, external validation was performed from the oral baricitinib trial in 2021-2023. A total of 24 patients were enrolled in the topical ruxolitinib and oral baricitinib trials. Inclusion criteria is age of at least 18 years with biopsy proven cutaneous LP lesions. Patients were excluded by atypical variants of LP and other active cutaneous conditions. The main outcome was to compare lpCAILS scores' correlation with Physician Global Assessment (PGA) and area under the curve (AUC) for treatment. The lpCAILS optimized erythema scoring had the highest correlation with PGA (0.63). In the internal validation cohort (N = 87 lesions), among eight (9.2%) measured greater than 4 cm², the optimized composite score demonstrated similar correlation with PGA and comparable AUC to mCAILS. The optimized subscore size had higher correlation with PGA (0.65 vs. 0.61). In external validation (N = 89 lesions), 15 (16.9%) were greater than 4 cm² in size. lpCAILS had higher correlations with PGA and (comparable AUCs) to mCAILS for composite score (0.8 vs. 0.78 (93.5% vs. 95.4%)) and subscore domains of erythema (0.79 vs. 0.78 (96.1% vs. 95.5%)), scale (0.76 vs. 0.73 (94.6% vs. 94.2%)), and elevation (0.73 vs. 0.69 (93.8% vs. 92.8%)), except for size (0.75 vs. 0.85 (86.3% vs. 91.9%)). Future studies with larger comparative arms and reliability analyses will be necessary to confirm lpCAILS as a validated disease measurement tool for cutaneous LP that can be used by medical professionals to track LP severity in research studies and clinical practice.Trial registration: CT03697460, NCT05188521.