Oophorectomy and risk of non-alcoholic fatty liver disease and primary liver cancer in the Clinical Practice Research Datalink.

Incidence of non-alcoholic fatty liver disease (NAFLD) and liver cancer are 2-3 times higher in males than females. Hormonal mechanisms are hypothesized, with studies suggesting that oophorectomy may increase risk, but population-based evidence is limited. Thus, we conducted a study within the Clinical Practice Research Datalink, with controls matched to cases of NAFLD (n = 10,082 cases/40,344 controls) and liver cancer (n = 767 cases/3068 controls). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression. Effect measure modification by menopausal hormone therapy (MHT) was examined, using likelihood ratio tests and relative excess risk due to interaction (RERI). Oophorectomy was associated with a 29% elevated NAFLD risk (OR = 1.29, 95% CI 1.18-1.43), which was more pronounced in women without diabetes (OR = 1.41, 95% CI 1.27-1.57) and in women who had oophorectomy prior to age 50 (OR = 1.37, 95% CI 1.22-1.52). Compared to women without oophorectomy or MHT use, oophorectomy and MHT were each associated with over 50% elevated risk of NAFLD. However, the combination of oophorectomy and MHT showed evidence of a negative interaction on the multiplicative (p = 0.003) and additive scales (RERI = - 0.28, 95% CI - 0.60 to 0.03, p = 0.08). Oophorectomy, overall, was not associated with elevated liver cancer risk (OR = 1.16, 95% CI 0.79-1.69). These findings suggest that oophorectomy may increase the risk of NAFLD, but not liver cancer.