Factors associated with bone response to teriparatide in young postmenopausal women with osteoporosis.

Introduction: To investigate the factors associated with changes in vertebral bone mineral density during teriparatide treatment.

Materials And Methods: Single centre, longitudinal study involving 145 osteoporotic postmenopausal women treated with teriparatide. Clinical evaluation, bone mineral density (BMD) measurements assessment and laboratory analyses were performed at baseline then after 12 and 18 months of treatment. Bone non-response to treatment was defined as no significant increase in BMD at 18 months as compared to baseline.

Results: Of the 145 women initially included, 109 completed the 18-month course of the treatment. 75% of them had a history of prior osteoporotic treatment. Baseline mean age was 60 ± 8 years. Mean baseline vertebral T-score was - 3.7 ± 0.7 and 83 (76%) women had suffered at least one vertebral fracture. At the end of treatment, 18 women (17%) were classified as non-responders. In the responder group (n = 91), vertebral BMD increased by 0.091 ± 0.04 g/cm (12.2 ± 5.3%). Clinical characteristics, baseline BMDs and the percentage of women previously treated with bisphosphonates as well as the duration of prior treatment did not significantly differ between the two groups of responders and non-responders. At baseline, non-responders had significant mean lower C-terminal fragment of type 1 collagen (CTX) values than responders (p < 0.01). Only baseline CTX values (r = 0.30 p < 0.01) were independently correlated to vertebral BMD changes during teriparatide treatment.

Conclusion: A minority of treated women had no vertebral densitometric gain after 18 months of teriparatide therapy. Low levels of baseline bone remodeling were the main factor associated with poor response to treatment.