The Incidence and Risk Factors of Non-Alcoholic Fatty Liver Disease: A Cohort Study from Iran

Background: Non-alcoholic fatty liver disease (NAFLD) is a condition with a global prevalence of 24%. A broad spectrum of liver complications has been attributed to this condition. Objectives: This study was conducted to determine the incidence of NAFLD and its potential risk factors in a seven-year follow-up study in Iran. Methods: This is a prospective cohort population-based study conducted in the northern region of Iran. In phase I of the cohort study, 2,461 participants were selected, between 2009 and 2010, using the stratified randomization method based on the sex and age of individuals. Ultrasonographic examination was performed again after a seven-year follow-up between 2016 and 2017. The multiple binary regression analysis was applied to evaluate the association between the development of NAFLD and potential risk factors. Results: The incidence of NAFLD was 27.88% (95% CI: 25.41% - 30.35%) in men and 30.17% (95% CI: 27.40% - 32.94%) in women (P = 0.226) in a seven-year followup period. Based on the multiple binary logistic regression analysis, body mass index (BMI) [OR = 1.219 (95% CI: 1.162 - 1.278) P 0.001], triglyceride (TG) [OR = 1.003 (95% CI: 1.001 - 1.005); P = 0.005] and high-density lipoprotein (HDL) [OR = 0.986 (95% CI: 0.972 - 0.999); P = 0.046] showed a significant association with the incidence of NAFLD in men. In contrast, the marital status [OR = 2.141 (95% CI: 1.286 - 3.565); P = 0.003], BMI [OR = 1.165 (95% CI: 1.121 - 1.211); P 0.001] and homeostatic model assessment for insulin resistance (HOMA-IR) [OR = 1.164 (95% CI: 1.041 - 1.301); P = 0.007] had a significant relationship with the incidence of NAFLD in women. Conclusions: It seems that NAFLD is markedly rising in the northern part of Iran. Higher levels of BMI, TG, and HDL are considered independent risk factors for the development of NAFLD in men, while the marital status, BMI, and HOMA-IR exhibited independent risk factors with the incidence of NAFLD in women.