THE CLINICAL CHARACTERISTICS AND EFFICACY OF BISPHOSPHONATES IN AUDLT PATIENTS WITH OSTEOGENESIS IMPERGECTA.

ABSTRACT

OBJECTIVE: Osteogenesis imperfecta (OI) is characterized by low bone mass and recurrent fractures. Adults with OI are often treated with oral or intravenous bisphosphonates (BPs). We investigated the clinical phenotypes of adult OI patients and prospectively compared the efficacy of oral alendronate (ALN) with intravenous zoledronic acid (ZOL) in OI patients. METHODS: This 24-month, observational, randomized clinical study included 60 adult patients with OI. We compared the differences in bone mineral density (BMD) and bone turnover biomarkers between OI adults and healthy subjects. Thereafter, OI patients were randomized at a 21 ratio to receive either weekly oral ALN 70 mg or once-yearly infusion of ZOL 5 mg. The efficacy outcomes were changes in BMD, bone turnover biomarkers, and fracture incidence. RESULTS: Adult OI patients had significantly lower BMD and significantly higher cross-linked C-telopeptide of type I collagen (ß-CTX) levels than age-/sex-/BMI-matched healthy subjects. A total of 52 patients completed the 24-month clinical study. BMD at lumbar spine, femoral neck, and total hip were equivalently elevated in the ALN (10.5, 13.2, and 14.7%, respectively) and ZOL (11.3, 13.7, and 11.7%, respectively; all P>.05) groups. Serum alkaline phosphatase decreased by 30.3% in the ALN group and 37.3% in the ZOL group (P = .12), and ß-CTX decreased by 58.0% in the ALN group and 63.6% in the ZOL group (P = .48). Compared to the prior fracture rates, clinical fracture incidences were decreased in the ALN and ZOL groups (both P<.05). CONCLUSION: Adults with OI present significantly lower bone mass and higher bone resorption biomarkers than healthy populations. Oral ALN and intravenous ZOL are equally effective at increasing BMD and inhibiting bone turnover in adults with OI. The treatment may reduce fractures in this study, but further efforts are still needed to demonstrate the anti-fracture efficacy of BPs. ABBREVIATIONS 25OHD = 25-hydroxyvitamin D ALN = alendronate ALP = alkaline phosphatase BMD = bone mineral density BMI = body mass index BP = bisphosphonate ß-CTX = cross-linked C-telopeptide of type I collagen FN = femoral neck LS = lumbar spine OI = osteogenesis imperfecta RCT = randomized controlled trial TH = total hip ZOL = zoledronic acid.