Clinical Question: How effective is human parathyroid hormone (hPTH) for the primary and secondary prevention of fractures in patients with osteoporosis?
Setting: Outpatient (any)
Study Design: Systematic review
Synopsis: hPTH comes in variants of 34 and 84 amino acids (hPTH [1-34] and hPTH [1-84]). The former is known as teriparatide (Forteo) and is labeled in the United States for use in patients with severe osteoporosis. It must be given by subcutaneous injection and costs approximately $700 per month. The authors of this systematic review identified all randomized controlled trials (RCTs) of at least one year’s duration that studied post-menopausal women, or men with osteoporosis. The authors identified 12 relevant RCTs that formed the basis for this review. Seven of these studies were double-blinded, two reported allocation concealment adequately, and two lost more than 20 percent of patients to follow-up.
The eight studies of postmenopausal women showed that teriparatide reduced the risk of vertebral and nonvertebral fracture in women with previous vertebral fracture. Hip fracture was not studied, and no studies comparing hPTH with bisphosphonates reported fracture as an outcome. Three studies of men with osteoporosis demonstrated increases in bone density with teriparatide compared with calcium and vitamin D alone, but none of these studies reported fracture as an outcome.
Bottom Line: There is consistent evidence that hPTH reduces the risk of recurrent fracture in very–high-risk women with osteoporosis and a history of fracture. The guideline that accompanies the article reports that the number needed to treat (NNT) with teriparatide for 21 months to prevent one vertebral fracture is 11, and the NNT for 21 months to prevent one nonvertebral fracture is 34. This compares with NNTs of 9 and 34, respectively, for 36 months of alendronate (Fosamax). Given the much lower cost and greater convenience of alendronate and other bisphosphonates, teriparatide should be reserved for a highly select group of patients with osteoporosis. (Level of evidence: 1a)