Association of estrogen replacement therapy with the risk of osteoarthritis of the hip in elderly white women. Study of Osteoporotic Fractures Research Group.

OBJECTIVE

To determine whether postmenopausal estrogen replacement therapy is associated with a reduced risk of radiographic findings of osteoarthritis (OA) of the hip.

DESIGN

Cross-sectional study.

SUBJECTS

White women (N = 4366; age, > or = 65 years) who were participants in a cohort study of osteoporotic fractures.

MEASUREMENTS AND METHODS

Radiographs of the pelvis that were obtained in all subjects were assessed for radiographic features of OA of the hip on a summary scale of 0 (none) to 4 (severe OA). Postmenopausal estrogen use was assessed by interview. The association of current and past oral estrogen use with OA of the hip was analyzed by using logistic regression, adjusting for potential confounding variables (eg, indicators of osteoporosis and correlates of estrogen use).

RESULTS

Five hundred thirty-nine women (12.3%) had mild or greater radiographic findings of OA of the hip in at least 1 hip, and 214 women (4.9%) had moderate to severe findings; 17% and 24% of the women were current and past users of oral estrogen, respectively. Women who were currently using oral estrogen had a significantly reduced risk of any OA of the hip (adjusted odds ratio [OR], 0.62; 95% confidence interval [CI], 0.49-0.86) and moderate to severe manifestation of disease (OR, 0.54; 95% CI, 0.33-0.88). Current users who had taken estrogen for 10 years or longer had a greater reduction in the risk of any OA of the hip (OR, 0.57; 95% CI, 0.40-0.82) compared with that of users for less than 10 years (OR, 0.75; 95% CI, 0.47-1.24). Current estrogen use for 10 years or longer was associated with a nonsignificant trend for a reduced risk of moderate to severe symptomatic disease (OR, 0.59; 95% CI, 0.28-1.29).

CONCLUSION

Postmenopausal estrogen replacement therapy may protect against OA of the hip in elderly white women.