Does Teriparatide Improve Outcomes in Osteoporotic Patients Undergoing Adult Spinal Deformity Surgery?

Commentary Mohanty and colleagues are commended for their research efforts on an important and timely topic. Optimization of bone health in the setting of surgery for adult spinal deformity (ASD) remains a critical research area. Although osteoporosis is a well-defined risk factor for reoperation and pseudarthrosis following ASD surgery, few studies have evaluated perioperative strategies to optimize bone health in patients with ASD1. The study by Mohanty et al. is a retrospective cohort analysis from a single-center, single-surgeon patient sample, evaluating the use of perioperative teriparatide for osteoporotic patients undergoing surgery for ASD and comparing their outcomes with cohorts of osteopenic patients and patients with normal bone mineral density (BMD). Patients treated with teriparatide were administered 20 µg daily, typically from 6 months before surgery to 18 months after surgery. Teriparatide is a synthetic version of human parathyroid hormone with an osteoanabolic effect that promotes increased BMD, and its use has been found to be associated with significant reductions in the rates of vertebral and nonvertebral fractures compared with use of bisphosphonates2. There are only 2 prior studies evaluating postoperative outcomes in osteoporotic patients with ASD who were treated with teriparatide; thus, the analysis by Mohanty et al. is clearly warranted3,4. The additional evidence presented by Mohanty et al. on the use of teriparatide to improve outcomes of ASD surgery is encouraging, but our approbation must be tempered. The propensity-matched analysis does not obviate the risk of selection and treatment bias in the retrospective, single-surgeon sample, and the unmatched analysis should be reviewed with caution given the differences in baseline patient demographic and surgical characteristics between cohorts. One of the main strengths of the study by Mohanty et al. is that the number of osteoporotic patients with ASD who were treated with teriparatide (78) is twice as large as in the prior studies by Yagi et al.3 (43) and Seki et al.4 (33). However, both of the Japanese studies were conducted prospectively, whereas Mohanty et al. used a retrospective matched-cohort design. In addition, there are other substantial differences in methodology across the studies, including in the inclusion criteria, comparison cohorts, and duration of teriparatide administration. Yagi et al.3 included osteoporotic and osteopenic patients with ASD (BMD T-score < –1.0) and compared the outcomes with and without teriparatide, excluded patients treated with 3-column osteotomy, and administered 20 µg of teriparatide once a day from the day after surgery to 18 months after surgery. In contrast, Seki et al.4 included only osteoporotic patients and compared the outcomes with teriparatide to those with bisphosphonate, included patients treated with 3-column osteotomy, and administered 20 µg of teriparatide once a day from 3 months before surgery to 21 months after surgery followed by bisphosphonate to lock in the BMD gain. Also, the studies by Yagi et al.3 and Seki et al.4 were each performed in Japanese patients at a single institution, limiting the generalizability of those studies. However, that also applies to the study by Mohanty et al., which was performed at a single center (a U.S. spine hospital) as well and involved a single surgeon with extensive experience with ASD surgery, thus limiting the ability to translate the results to other spine surgeons and practice settings. The trend of these 3 studies appears to support an association of teriparatide treatment with improved outcomes and reduced complications; however, the body of evidence remains heterogeneous, with a limited ability to pool and compare data to determine the treatment effect of teriparatide in osteoporotic patients with ASD. A few additional important points must be considered when discussing the use of teriparatide. First, the cost of teriparatide is high: approximately $850 per week of treatment (wholesale cost, $3,426.50 for a 4-week supply)1. However, the high cost of osteoanabolic agents such as teriparatide must be weighed against the reduction in the costs and health-care burden due to complications and reoperations following ASD surgery. Future studies are needed to assess the cost-effectiveness and value of various pharmacotherapeutic treatments for perioperative bone health optimization in patients with ASD. Also, while the risk appears low, the use of teriparatide should be limited to 24 months because of concerns regarding inducement of osteosarcoma. Finally, prescribing pharmacotherapeutic agents and monitoring bone health can be burdensome to the spine surgeon, and a multidisciplinary team approach should be utilized to coordinate care for patients with ASD who have osteoporosis.