Bone Abstracts

Objectives: The purpose of our study was to evaluate the bone mineral accrual in children with osteogenesis imperfecta (OI) treated by pamidronate (PAM).

Methods: In retrospective study 43 children with different types of OI were included: 17 boys (39.5%) and 26 girls (60.5%). According to clinical OI, patients were: OI I type -13 (30.2%), OI III type – 24 (55.9%) OI IV type – 4 (9.3%), OI V type 1 (2.3%) and Bruck syndrome 1 (2.3%). The standard protocol with cyclic PAM infusions (3 consequent days 3–4 times in a year) was applied in annual cumulative dose ranged from 9 to 12 mg/kg. The observation period was 24 months. Bone mineralization parameters were detected by dual-energy X-ray absorptiometry of lumbar spine L1–L4 (densitometer Hologic QDR 4500C, with pediatric reference database). We evaluated bone mineral density (BMD) - Z-score, measured in standard deviations and deficiency in percentages. All patients were divided into 2 groups: 1st group (mild-OI I type) and 2nd group (moderate-severe, all other types).

Results: During 2 years of PAM treatment we have observed BMD-Zscore accrual (P=0.000001), decreasing the BMD deficiency (P=0.0007) and fracture rate reduction (P=0.003). BMD-Zscore increased from −3.2 (−4.5; −2.2) SD to SD in 1 year (P=0.0003); −2.4 (−3.7; −1.4) SD in 2 years (P=0.005). The deficiency of BMD changed from −34.0% (−22.0; −46.0) to −27.0% (−17.0; −38.0) in 1 year (P=0.0001); −23.0% (−12.0%; −26.0%) in 2 years (P=0.00009). Patients with OI I type had more intensive bone mineral accrual compare to moderate-severe patients: in 1 year: BMD Zscore +50.0% (4.9–68.4) vs +3.2% (0–15,9), P=0.077; BMD deficiency +13.0% (4.2–31.8) vs +5.6% (2.6–29.4), P=0.022; in 2 years: BMD Zscore +53.7% (24.6–67.1) vs +14.3 (5.6–20)%, P=0.01; BMD deficiency +34.3% (24–54.1) vs +16.4% (4.7–26.8), P=0.022; CONCLUSION: PAM treatment was effective in bone mineral accrual and fracture reduction. Patients with mild form of OI increased BMD more effective then moderate-severe forms.

Disclosure: The authors declared no competing interests.