{"paper_id":"cdb94392-0df4-4935-ac43-31ac5ac5050e","body_text":"International Journal of Women's Health (Jan 2026)\nEvaluating the Role of Lipid Accumulation Product Index in Endometriosis: Findings from NHANES and Mendelian Randomization\nAbstract\nNenghuan Tang,1– 3,* Can Luo,3,* Li Hu,3,4 Fan Xu1 1Department of Gynecology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, People’s Republic of China; 2Department of obstetrics and gynecology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China; 3Department of Clinical Medical College, North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China; 4Department of Obstetrics and Gynecology, the Affiliated Nanchong Central Hospital of North Sichuan Medical College, Nanchong, Sichuan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fan Xu, Department of Gynecology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, People’s Republic of China, Tel +86-15984877283, Email xufanyidingxin@163.comPurpose: Endometriosis is increasingly recognized as a condition linked to metabolic health. The lipid accumulation product (LAP) index, a simple index reflecting lipid metabolism and hormonal imbalance, is widely used in assessing metabolic disorders. This study investigates the association between LAP index and endometriosis risk.Patients and Methods: Using data from the 1999– 2006 National Health and Nutrition Examination Survey (NHANES), we examined the association between LAP index and endometriosis through multivariable logistic regression, subgroup analyses, and restricted cubic spline (RCS) models. Two-sample Mendelian randomization (MR) analysis was performed using FinnGen data to assess the potential causal effects of triglycerides (TG) and waist circumference (WC), the two key components of LAP index, on the risk of endometriosis.Results: From the NHANES data, we included 1803 eligible participants, of whom 144 (8.0%) had endometriosis. Multivariable logistic regression models indicated that elevated LAP index levels were associated with an increased risk of endometriosis after adjusting for potential confounding variables (OR = 1.489, 95% CI: 1.074– 2.065, P = 0.0218). Furthermore, restricted cubic spline analysis revealed a positive linear relationship (P = 0.0026). Two-sample Mendelian randomization analysis showed that genetic prediction supported a causal association between higher TG levels and an increased risk of endometriosis (OR= 1.14, 95% CI: 1.06– 1.22, P= 0.0001, FDR = 0.00257), but the association was not observed between WC and endometriosis (OR=0.99, 95% CI: 0.83– 1.20, P=0.956, FDR = 0.983).Conclusion: LAP index is positively associated with endometriosis risk in women. MR analysis suggests a potential causal role of TG, possibly underlying this association.Keywords: lipid accumulation product index, endometriosis, national health and nutrition examination survey, mendelian randomization","source_license":"CC0","license_restricted":false}