Treatment with parathyroid hormone reduces osteoporotic vetebral fracture risk

At final follow-up, hormone-treated patients had a mean total hip BMD increase 2.1% higher than placebo patients.

Treating postmenopausal osteoporotic women with a recombinant human parathyroid hormone reduced their overall risk for sustaining new or worsened vertebral fractures, a prospective, randomized study found.

"[Our] results demonstrate that PTH (parathyroid hormone) seems to be an efficacious and generally well-tolerated agent for reducing the risk for new or worsened vertebral fractures in postmenopausal women with or without previous vertebral fracture," the study authors wrote.

"Although the magnitude of the risk reduction was sensitive to assumptions about fracture incidence in patients who did not complete the study, the findings suggest that PTH provides a therapeutic option for women with osteoporosis who have not yet had a fracture but are at increased risk for fracture," they reported.

Susan L. Greenspan, MD, and colleagues at 168 centers in nine countries conducted the study, called the Treatment of Osteoporosis with Parathyroid Hormone study. Investigators compared the safety and efficacy of PTH (1-84) vs. placebo for preventing osteoporotic vertebral fractures.

Of 2,532 women who agreed to participate, investigators assigned 1,246 to the placebo group and 1,286 to the PTH group. Of these, 877 placebo patients (70%) and 824 PTH patients (64%) completed the study.

At 18 months' follow-up, investigators found that 59 women had developed a new vertebral fracture and one woman had a worsened vertebral fracture. The one patient with the worsened fracture was part of the PTH treatment group. Of the 59 new fractures, 42 occurred in the placebo group and 17 occurred in the PTH group, according to the study.

"When we excluded the single participant with a worsened fracture from the analysis, the relative risk for a new vertebral fracture in the PTH group was 0.39 compared with placebo with a [number needed to treat for benefit] of 49," the authors wrote.

Investigators also found that lumbar spine BMD significantly increased in the PTH group at 6 months' follow-up and continued to through to final follow-up.

At 18 months' follow-up, lumbar spine BMD had increased 6.9% for PTH-treated patients compared to placebo-treated patients. Also, BMD increased by 10% or more for 212 (24.7%) PTH-treated women compared with 15 (1.6%) women treated with placebo (P<.001).

At 6 months follow-up, total hip and femoral neck BMD had slightly decreased in both groups. However, for PTH-treated patients, total hip and femoral neck BMD significantly increased over baseline values at 12 months and 18 months' follow-up, but continued to decrease among placebo patients, according to the study.

At final follow-up, PTH-treated patients had a mean increase in total hip BMD 2.1% higher than the placebo group, 2.5% higher for the femoral neck and 1.6% higher for the trochanter (P<.001), according to the study.

For more information:
Greenspan SL, Bone HG, Ettinger MP, et al. Effect of recombinant human parathyroid hormone (1-84) on vertebral fracture and bone mineral density in postmenopausal women with osteoporosis. Ann Intern Med. 2007;146:326-339.