Laparoscopically confirmed endometriosis and midlife plasma markers of inflammation, cholesterol, and adipokines among participants in the Nurses' Health Study II

Objective: Endometriosis may increase the risk of cardiovascular disease, possibly through a detrimental impact on circulating biomarkers. However, there is a paucity of research on endometriosis and inflammation, lipids, and adipokines at midlife. Methods: We used generalized linear models to determine the association between laparoscopically confirmed endometriosis and log-transformed levels of plasma C-reactive protein (n = 3936), interleukin-6 (n = 3495), tumor necrosis factor-alpha receptor 2 (n = 2967), high-density lipoprotein cholesterol (n = 1533), low-density lipoprotein cholesterol (n = 1324), total cholesterol (n = 4898), leptin (n = 2480), and adiponectin (n = 4262) among participants with existing biomarker measurements in the Nurses' Health Study II (average age 44 years). We investigated heterogeneity by body mass index (<25 kg/m² vs. ≥ 25 kg/m²). Results: We did not observe associations between endometriosis and midlife inflammatory biomarkers (C-reactive protein % difference: -4.6, 95 % CI [−15.7,7.9]; interleukin-6: −0.4 % [−7.2,7.1]; tumor necrosis factor-alpha receptor 2: −1.3 % [−4.1,1.6]) or levels of high-density lipoprotein cholesterol (0.8 % [−3.7,5.6]), low-density lipoprotein cholesterol (−0.2 % [−5.2,5.1]), total cholesterol (1.0 % [−0.7,2.7]), or adiponectin (−4.0 [−8.8,1.0]). Women with endometriosis had higher leptin levels (9.0 % [0.5, 18.1]). Associations varied by body mass index for total cholesterol (p-value 0.05) and leptin (p-value 0.02). Among women with a body mass index ≥25 kg/m², those with endometriosis had a mean total cholesterol level that was 2.7 % higher (0.2,5.2) than among those without; among those with a body mass index <25 kg/m², those with endometriosis had a mean leptin level that was 15.7 % higher (4.6, 28.1) than among those without endometriosis. Conclusions: Endometriosis was not associated with midlife systemic inflammation, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or adiponectin. Endometriosis was associated with higher leptin among those with a body mass index <25 kg/m² and higher total cholesterol among those with a body mass index ≥25 kg/m². These findings suggest that endometriosis may influence cardiovascular disease risk via midlife cholesterol and leptin.