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Exogenous estrogen as mediator of racial differences in bioactive insulin-like growth factor-I levels among postmenopausal women.

ABSTRACT: The role of exogenous estrogen use in racial differences in insulin-like growth factor-I (IGF-I) levels which affect cancer risk is unclear. We investigated whether the relationship between race and circulating bioactive IGF-I proteins was mediated by exogenous estrogen and the extent to which exogenous estrogen influenced the race-IGF-I relationship in postmenopausal women.This cross-sectional study included 636 white and 133 African American postmenopausal women enrolled in an ancillary study of the Women's Health Initiative Observational Study. To assess exogenous estrogen use (nonusers [n = 262] vs users [n = 507]) as a mediator of the race-IGF-I relationship, we used the Baron-Kenny method and an estimation of the proportional change in the odd ratios for IGF-I levels on race plus a bootstrapping test for the significance of the mediation effect.Compared with white women, African American women were more likely to have high IGF-I levels and less likely to use exogenous estrogen. After accounting for race, estrogen nonusers had higher IGF-I levels than estrogen users did. Among oral contraceptive ever users, exogenous estrogen had a strong mediation effect (67%; p = .018) in the race-IGF-I relationship. In the women with a history of hypertension, exogenous estrogen explained racial differences in IGF-I levels to a modest degree (23%; p = .029).Exogenous estrogen use has a potentially important role in disparities in IGF-I bioactivity between postmenopausal African American and white women. A history of oral contraceptive use and hypertension may be part of the interconnected hormonal pathways related to racial differences in IGF-I levels.

SUBMITTER: Jung SY

PROVIDER: S-EPMC4447798 | biostudies-other | 2015 Apr

REPOSITORIES: biostudies-other

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Exogenous estrogen as mediator of racial differences in bioactive insulin-like growth factor-I levels among postmenopausal women.

Jung Su Yon SY Vitolins Mara Z MZ Paskett Electra D ED Chang Shine S

The journals of gerontology. Series A, Biological sciences and medical sciences 20140918 4

<h4>Background</h4>The role of exogenous estrogen use in racial differences in insulin-like growth factor-I (IGF-I) levels which affect cancer risk is unclear. We investigated whether the relationship between race and circulating bioactive IGF-I proteins was mediated by exogenous estrogen and the extent to which exogenous estrogen influenced the race-IGF-I relationship in postmenopausal women.<h4>Methods</h4>This cross-sectional study included 636 white and 133 African American postmenopausal wo ...[more]

PMID: 25238773

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Project description:BACKGROUND:The differences in the incidence of heart failure by race/ethnicity and the potential mechanisms for these differences are largely unexplored in women. METHODS AND RESULTS:A total of 156 143 postmenopausal women free of self-reported heart failure enrolled from 1993 to 1998 at 40 clinical centers throughout the United States as part of the Women's Health Initiative and were followed up until 2005, for an average of 7.8 years, for incident hospitalized heart failure. Incident rates, hazard ratios (HRs), and 95% confidence intervals were determined by use of the Cox proportional hazard model comparing racial/ethnic groups, and population-attributable risk percentages were calculated for each racial/ethnic group. Blacks had the highest age-adjusted incidence of heart failure (380 in 100 000 person-years), followed by whites (274), Hispanics (193), and Asian/Pacific Islanders (103). The excess risk in blacks compared with whites (age-adjusted HR=1.45) was significantly attenuated by adjustment for household income (HR=0.97) and diabetes mellitus (HR=0.89), but the lower risk in Hispanics (age-adjusted HR=0.72) and Asian/Pacific Islanders (age-adjusted HR=0.44) remained despite adjustment for traditional risk factors, socioeconomic status, lifestyle, and access-to-care variables. The effect of adjustment for interim coronary heart disease on nonwhite versus white HRs for heart failure differed by race/ethnic group. CONCLUSIONS:Asian/Pacific Islander and Hispanic women have a lower incidence of heart failure and black women have higher rates of heart failure compared with white women. The excess risk of incident heart failure in black women is explained largely by adjustment for lower household incomes and diabetes mellitus in black women, whereas the lower rates of heart failure in Asian/Pacific Islanders and Hispanics are largely unexplained by the risk factors measured in this study. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000611.

Dataset Information

Exogenous estrogen as mediator of racial differences in bioactive insulin-like growth factor-I levels among postmenopausal women.

Publications

Exogenous estrogen as mediator of racial differences in bioactive insulin-like growth factor-I levels among postmenopausal women.

Similar Datasets

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