Causal Inference
Analysis of the long-term incidence trend of hypothyroidism with Oral Lichen Planus in Taiwan Yu-Ching Chou* Shih-yi CHen Fu-Huang Lin Chien-An Sun
Chen-Shih Yi1, Fu-Huang Lin1, Chien-An Sun2, Yu-Ching Chou1*
1School of Public Health, National Defense Medical Center, Taipei, 2Department of Public Health, College of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
*Corresponding author: trishow@mail.ndmctsgh.edu.tw
Background: Hypothyroidism is a common endocrine disorder characterized by insufficient thyroid hormone secretion, impacting multiple systemic functions. Oral lichen planus (OLP) is a chronic immune-mediated oral mucosal disease potentially associated with thyroid dysfunction. Immune dysregulation is hypothesized to connect these conditions. However, large-scale evidence on their relationship and the role of comorbidities remains limited.
Methods: This descriptive study utilized data from the Taiwan National Health Insurance Research Database (NHIRD) between 2000 and 2013. Approximately 30,260 newly diagnosed cases of hypothyroidism (ICD-9: 2449, 2452) and subsequent occurrences of OLP (ICD-9: 697) were identified. Individuals aged >20 years were included in the analysis, with data stratified by age, sex, and healthcare utilization patterns.Annual incidence rates of hypothyroidism and OLP were calculated per 10,000 individuals. Long-term trends in incidence rates were analyzed using linear trend analysis to assess changes over the 14-year period.
Results: The incidence rate of hypothyroidism among the general population decreased from 11.74 per 10,000 individuals in 2000 to 9.97 in 2013. Conversely, the incidence rate of oral lichen planus (OLP) among hypothyroidism patients increased from 0.71 per 10,000 individuals in 2000 to a peak of 6.30 in 2012 before slightly declining to 5.85 in 2013.Age-specific incidence rates of OLP rose across all age groups from 2000 to 2013, with the highest increase observed among patients aged ≥60 years. The incidence rate among this group showed a steeper rise compared to younger age groups.
Regarding healthcare utilization, patients with more frequent clinical visits for hypothyroidism exhibited higher OLP incidence rates. Specifically, the incidence rates were 6.32 per 10,000 individuals for those with ≤3 visits, 8.44 for 4–37 visits, and 7.62 for ≥38 visits. These findings suggest that higher healthcare utilization may be associated with increased detection of OLP cases..
Conclusion: Over the past 14 years, the incidence of OLP among hypothyroidism patients has increased, particularly in older age groups and those with higher healthcare utilization. These findings emphasize the need for further research to explore the mechanisms linking hypothyroidism and OLP, aiding in the development of prevention and intervention strategies.
Keywords: Hypothyroidism, Oral Lichen Planus, Comorbidity, Immune Regulation.