Factors Associated with Periductal Fibrosis Diagnosed by Ultrasonography Screening among a High Risk Population for Cholangiocarcinoma in Northeast Thailand

Background: The population in northeast Thailand continues to present with hepatobiliary abnormalities, particularly periductal fibrosis (PDF) which is the result of chronic infection with liver fluke (Opisthorchis viverini; OV) and may lead to the development of cholangiocarcinoma (CCA). Although the prevalence of OV infection has been decreased due to a liver fluke control program over decades, the prevalence of PDF remains high. This study aimed to investigate demographic factors associated with PDF risk based on ultrasonography (US) screening. Materials and Methods: This cross-sectional study is part of the Cholangiocarcinoma Screening and Care Program (CASCAP), a prospective cohort study. Multiple logistic regression was used for data analysis. Results: In 55,246 subjects, the overall prevalence of PDF was 33.0% (95%CI: 32.6 - 33.4). Males (33.9 %) were at higher risk for developing PDF than females (32.2 %) (ORcrude = 0.93; 95%CI: 0.89 - 0.96; p-value < 0.001). Factors associated with an increased PDF risk, in addition to OV infection, included old age (${\geq}70$ years) (ORadj = 1.28, 95% CI: 1.14 - 1.44, p < 0.001) and hepatitis B infection (ORadj = 1.31, 95% CI: 1.11 - 1.55, p = 0.001). In contrast, number of praziquantel treatments (> 2 times) (ORadj = 0.54, 95% CI: 0.47 - 0.63, p < 0.001) and diabetes mellitus (ORadj = 0.57, 95% CI: 0.49 - 0.65, p < 0.001) were significantly associated with a decreased PDF risk. Conclusions: Future US screening should closely examine older people and hepatitis B subjects for the purpose of PDF surveillance among high risk groups for CCA. However, the results of inverse associations require further investigation in order to confirm our findings.