Long-term estrogen replacement therapy prevents bone loss and fractures.

Although several case-control studies have shown an inverse association between postmenopausal estrogen use and fractures, quantitation of fracture incidence has been lacking. To quantify the degree to which estrogen replacement therapy prevents postmenopausal osteoporosis, a retrospective study was done comparing the occurrence of fractures in 245 long-term estrogen users and 245 case-matched controls, followed for an average of 17.6 years. Quantitative bone mineral assessments were obtained from 18 women using estrogen replacement therapy and their controls (average age, 73 years). Osteoporotic fracture incidence in estrogen users was 50% as great as in the controls (p less than 0.01). Estrogen users showed significantly greater bone mineral: 54.2% greater spinal mineral (p less than 0.0002), 19.4% greater forearm mineral (p less than 0.0005), and 15.6% greater metacarpal cortical thickness (p less than 0.005). Long-term estrogen replacement therapy confers significant protection against bone loss and fracture.