A total of 236 OLP patients (41 males and 195 females, mean age 51.70±13.99 years) and 226 gender- and age-matched healthy controls (52 males and 174 females, mean age 49.46±17.27 years) were enrolled in this study. All participants were evaluated from July 2015 to March 2019 at the Department of Oral Medicine, Shanxi Provincial People’s Hospital, China. The diagnosis of OLP was established according to the recommended diagnostic criteria [2,3,11,12]. The characteristic clinical manifestations alone, such as bilateral grayish-white Wickham striae or papules may allow diagnosis, especially if classic skin or other extraoral lesions exist concomitantly. Besides the clinical examination, the biopsy for histopathological examination was routinely performed. When necessary, direct immunofluorescence (DIF) was employed to differentiate from autoimmune blistering diseases, such as pemphigus and pemphigoid. Specifically, any patient suspected of having oral lichenoid lesions, including contact hypersensitivity reactions, drug-induced reactions, paraneoplastic pemphigus and chronic graft-vs.-host disease, was not enrolled in the present study. Those who were diagnosed as having other oral mucosal lesions, such as leukoplakia, mucosal hyperkeratosis, erythema multiforme and discoid lupus erythematosus were also excluded. In addition, patients who have concomitant systemic diseases, including benign or malignant tumors, HIV, rheumatic or autoimmune diseases, gastrointestinal diseases, liver and kidney diseases were equally excluded from this study. None of the healthy controls exhibited any oral mucosal lesions and had relevant systemic diseases. None of the participants had taken any nutritional supplements, including (but not limited to) folate, vitamin B12 or iron supplements, at least 3 months prior to this study.
This study was approved by the ethics committee of Shanxi Provincial People’s hospital and informed consent was obtained from each of the participants.
Laboratory methods
Blood samples were obtained from all participants after 12 hours of overnight fasting, the levels of hemoglobin (Hb), serum folate, vitamin B12, and ferritin were measured by the routine tests in the department of clinical laboratory of Shanxi Provincial People’s Hospital. Meanwhile, a thorough medical history was obtained from each participant and standard clinical examination of the oral cavity was also performed. The duration of OLP, which was estimated from the first time noticing oral discomfort, was recorded for each patient.
The accepted normal serum folate level and serum vitamin B12 level is 4.0–18.7 ng/mL and 180–914 ng/L, respectively. Serum ferritin level was used to assess iron status with a normal level of 11.0–306.8 ng/mL for females and 15–336.2 ng/ml for males. Serum vitamin B12, folate, and ferritin deficiency was defined as a serum level below its lower cutoff value, respectively. Anemia was diagnosed when the Hb level was lower than the lower cut-off value (male < 13 g/dL and female < 12 g/dL).
Clinical examination and scoring
REU (reticular/hyperkeratotic, erosive/erythematous, ulcerative) scoring system was adopted to evaluate the severity of OLP as previously reported [13,14]. Briefly, the oral cavity of each OLP patients was divided into 10 sites and the severity of the mucosal lesions in each site was scored according to the presence of reticular/hyperkeratotic, erosive/erythematous, and ulcerative lesions.
Data analysis
Statistical analyses were performed with SPSS software version 22.0 (SPSS Inc, Chicago, IL). The frequencies of hematinic deficiencies and anemia between OLP patients and health controls were compared using chi-square test. When the observed frequency was less than 1, the Fisher’s exact test was applied. Wilcoxon-Mann-Whitney rank sum test (U test) was used for the statistical comparison of REU scores between the OLP patients with and without hematinic deficiencies. Logistic regression analysis was conducted to assess whether the age and gender are the significant factors related to the presence of hematinic deficiencies (ferritin, folate and vitamin B12 deficiency) in the OLP patients and healthy controls, respectively. Spearman's correlation coefficient was applied to evaluate the association between OLP and hematinic deficiencies. A p-value < 0.05 was accepted as statistically significant.