An epidemiologic study of the role of exogenous and endogenous estrogens in rheumatoid arthritis
By: Louise Murphy.
Published: 2006
Language: eng
Number of pages: 171
ISBN-13: 9780494159101
Description: Etiologic studies of estrogens and rheumatoid arthritis (RA) have shown varying results. The primary objective of this case-control study was to investigate the etiologic role of exogenous and endogenous estrogens in RA, and the secondary to determine whether association estimates for each hormonal exposure differed by time since diagnosis. Cases (n=245) were women, aged 25 to 69, residents of the Greater Toronto Area (GTA), and diagnosed with RA within 10 years of ascertainment. Controls (n=244), matched on age (+/-10 years), were GTA residents attending the Toronto Western Orthopaedic Clinic for an accidental injury. Socio-demographic and health history information were collected in a self-administered questionnaire.Two series of models were examined: the first containing one main hormonal variable, and the second multiple hormonal variables. Hormonal exposures included history of OC use, hormone replacement therapy (HRT) use, pregnancy, live births, breastfeeding and menstruation. Four findings emerged in the first series: (1) current OC users had a strong decreased risk (OR=0.25; 95% CI=0.09, 0.73); (2) HRT use duration and RA were negatively associated (e.g., OR=0.1; 95% CI=0.0, 0.5 for HRT use >5.2 years), (3) parous women who breastfed were at least half as likely to develop RA than non-breastfeeders, and (4) menstrual years and risk of RA were negatively associated. In the second series (adjusted for hormonal exposures and potential confounders), there were two strong negative associations with RA: menstrual years (e.g., OR=0.1, 95% CI=0.01, 0.3 for >36.9 menstrual years), and lifetime weeks of breastfeeding (test for trend chi2df=4=15.62, p&lt;0.01, model limited to parous women). In the time since diagnosis analysis, there were some differences in the magnitude of ORs for the "ever used OCs", "ever pregnant", and "ever had a live birth" variables. For each hormonal exposure, results are consistent with current health communication messages. The differing results in the single and multiple hormonal exposure models demonstrates the need for multi-factorial studies of RA etiology, with comprehensive measurement and analysis of hormonal exposures and potential confounders. The heterogeneity of ORs in the time since diagnosis analysis indicates that diagnosis time should also be considered in future studies.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3739.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.