Effectiveness and safety of bisphosphonates therapy in secondary osteoporosis in children

Introduction: There are few studies on effectiveness and safety of bisphosphonate therapy in secondary osteoporosis in children. The aim of this research was to analyse effectiveness and safety of bisphosphonates in secondary osteoporosis in children.

Patients and methods: Multicentre retrospective study in patients younger than 18 suffering from secondary osteoporosis and who have received bisphosphonates. Clinical data were recorded. Bone mineral density (BMD) was assessed in terms of BMD Z-score in lumbar spine (ZBMDls) measured by dual-energy X-ray absorptiometry (DXA). Effectiveness was valued at changes in ZBMDls one and two years after the onset of bisphosphonates and at the decrese in the number of fractures a year. Adverse events reported were recorded. Descriptive and bivariant analysis was performed.

Results: 32 patients were recruited. ZBMDls increased one year after the onset of treatment ((-2.46 ± 0.96) vs. (-1.54 ± 1.38); p < .001). Fractures a year dicreased significantly (1 (1-2) vs. 0 (0-0.61); p < .001). ZBMDls increase was higher in patients who were able to walk (1.88 ± 0.72 vs. 0.55 ± 0.82; p = .07) and correlated positively with body mass index (BMI)- for- age percentile (rho: 0.564; p < .001). The decrease in the number of fractures a year was higher in patients with lower initial fracture rate (rho: -0,47; p = .006) and with higher initial ZBMDls (rho: -0.47; p = .07). 10 adverse events were reported in 7 patients (22%), all of them intravenous bisphosphonates related. No association was found between adverse events and studied variables.

Conclusions: Bisphosphonates are effective in secondary osteoporosis in children. Response seems to be better in patients who are able to walk, well-nourished and in the early stages of the disease. Adverse events were frequent but mild.