Parathyroidectomy associated with increased bone mineral density and decreased fracture rate in patients with primary hyperparathyroidism

1. In this retrospective cohort study, parathyroidectomy improved bone mineral density and reduced the overall fracture rate more than observation or bisphosphonates in patients with primary hyperparathyroidism.

2. Bisphosphonates were associated with a higher fracture rate than observation alone.

Evidence Rating Level: 2 (Good)

Study Rundown: Primary hyperparathyroidism (PHPT) is a common endocrine disorder that decreases bone mineral density (BMD), which puts affected patients at increased risk for fractures. While parathyroidectomy is an effective treatment for PHPT, not all patients who meet the criteria for this procedure receive it; they are often managed medically instead. In this retrospective cohort study, Kaiser Permanente Southern California (KPSC) patients with PHPT were placed into three groups for comparison: parathyroidectomy, bisphosphonate treatment, and no intervention. Primary outcomes were the change in baseline BMD and the fracture rate. In both men and women, parathyroidectomy and bisphosphonates increased hip BMD in the 2 years following diagnosis, while hip BMD fell in patients who received no treatment over the same period. While fracture risk increased on an annual basis in patients who were observed, it decreased annually in patients who underwent parathyroidectomy. Interestingly, bisphosphonates increased the annual risk for fracture more than observation alone. This study was limited by its non-random treatment assignment; however, its findings suggest that parathyroidectomy may merit consideration as the preferred treatment for PHPT.

Click to read the study published today in the Annals of Internal Medicine

Relevant Reading: Effects of parathyroidectomy versus observation on the development of vertebral fractures in mild primary hyperparathyroidism

In-Depth [retrospective cohort]: Among all patients enrolled in KPSC with biochemically confirmed PHPT, 6272 met inclusion criteria. Women with PHPT who received no treatment had a decreased total hip BMD of -7.3% at 5 to 8 years after diagnosis, compared to parathyroidectomy, which had an increase in BMD by 4.2% (p < 0.001), and bisphosphonates, which had an increase in BMD by 3.6% (p = 0.004), within 2 years of each intervention. Spine BMD remained stable in women who were not treated, while parathyroidectomy and bisphosphonate treatments both increased BMD by 6.3% and 11.9%, respectively, at >8 years. Findings in men were similar, except that bisphosphonates led to greater improvement in total hip BMD at >8 years (7.6%, p < 0.001 compared with no treatment), and spine BMD values increased over time regardless of intervention. For hip fracture risk, patients who were observed had an absolute risk of 4.3 events per 1000 patients at 1 year after diagnosis, 10.2 events at 2 years, 24.9 events at 5 years and 55.9 events at 10 years. Patients who underwent parathyroidectomy had a hip fracture absolute risk difference of -2.8 events per 1000 patients at 1 year, -6.6 events at 2 years, -16.0 events at 5 years and -35.5 events at 10 years. Surprisingly, bisphosphonates failed to reduce the fracture risk over observation, with absolute risk differences of +2.5 events per 1000 patients at 1 year, +5.9 events at 2 years, +14.0 events at 5 years and +29.7 events at 10 years.

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