Validation of instruments to measure the symptoms and signs of oral lichen planus

Objective The aim of this study was to validate the visual analog scale (VAS), numeric rating scale (NRS), and change in symptoms scale (CSS) in measuring symptoms of oral lichen planus, and the modified oral mucositis index (MOMI) in measuring the signs of oral lichen planus. Study design Criterion validity, construct validity, and internal consistency reliability were evaluated using data from a randomized, double blind, placebo-controlled clinical trial of curcuminoids in oral lichen planus. Results Moderate to high correlations were found between VAS, NRS, and CSS. Correlations of symptom scores with clinical signs ranged from minimal to high. Correlation of NRS with clinical signs was stronger than that of VAS with clinical signs. Significant changes from baseline at each follow-up in NRS, VAS, and MOMI scores were seen. The Cronbach α for erythema and ulceration scores from the MOMI were 0.66. Conclusions This study gives some evidence of the validity of NRS, VAS, CSS, and MOMI for use in oral lichen planus. The NRS has better construct validity than VAS, based on higher correlations with clinical signs. Erythema plus ulceration is a better measure than ulceration alone.