Fewer fractures occurred among kidney transplant (KT) patients following changes in the management of chronic kidney disease mineral bone disorder (CKD-MBD), researchers reported.
“Recent changes in clinical practice are associated with reductions in pre and posttransplant hyperparathyroidism, vitamin D deficiency, and fracture risk after KT,” Peggy Perrin, MD, and colleagues from the Strasbourg University Hospital in France, concluded in Transplantation.
Using a chart review, the investigators compared fracture incidence among KT recipients from a hospital. Group 1 (152 patients) underwent surgery from 2004 to 2006 and group 2 (137 patients) from 2009 to 2011. Some important changes occurred in the interval, notably a decrease in parathyroidectomy usage and increase in cinacalcet treatment (for hypercalcemia with secondary hyperparathyroidism [SHPT). The researchers acknowledged that they did not know how the 2009 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, which allowed parathyroid hormone (PTH) levels of 2 to 9 times the normal upper limit, might have influenced management of these patients.
Results from group 1 revealed 15 fractures in 13 patients: 12 were spontaneous and 3 followed trauma. According to imaging findings, fractures occurred in vertebrae, feet, upper and lower limbs, and ribs. In group 2, fractures were observed in 4 patients: 2 spontaneous fractures of vertebrae, 1 grade 1 vertebral fracture, and 1 ischio-pubic ramus fracture following a hard fall.
At the time of transplant, group 2 was receiving cinacalcet and cholecalciferol (vitamin D3) more often than group 1. Their lower PTH levels coincided with less severe SHPT. Vitamin D deficiency within the group fell from 64% to 20%.
After transplant, group 2 patients enjoyed lower rates of persistent hyperparathyroidism (PTH above 130 ng/L) and bone turnover. Cholecalciferol supplementation increased while active vitamin D therapy remained the same. Patients had twice the levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. In addition, they more frequently received low-dose bisphosphonates. A year after transplant, fracture incidence was significantly lower in group 2 (3.1% vs 9.1%).
“There are several possible explanations for the decrease in fracture incidence,” Dr Perrin and colleagues explained. “First, pretransplant osteodystrophy may be less important as severe HPT regressed, whereas the proportion of patients with low PTH levels was stable. Persistent HPT also decreased.”
Steroid sparing did not account for the results. Neither did traditional risk factors for fractures, such as age, sex, and diabetes. A quarter of group 2 patients had a history of fractures, but its prevalence in group 1 was unknown.
In light of the findings, the researchers encouraged future, large randomized trials to evaluate post-transplant fracture rates particularly with bisphosphonate and cinacalcet treatment. They reported no conflicts of interest.
1. Perrin P, Kiener C, Javier RM, et al. Recent changes in chronic kidney disease–mineral and bone disorders (CKD-MBD) and associated fractures after kidney transplantation. Transplantation [accepted manuscript]. Transplant. doi: 10.1097/TP.0000000000001449.