AB0881 DESCRIPTIVE ANALYSIS OF PATIENTS WITH OSTEOGENESIS IMPERFECTA IN A TERCIARY HOSPITAL IN MADRID
Authors: Cristina Pijoan Moratalla, María Andreina Teran Tinedo, Jose Renato Quiñones Torres
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with an incidence of 1 per 20,000 births. It is also called "brittle bone disease" and is most commonly caused by mutations in genes encoding type I collagen or proteins involved in its posttranslational modification. Most patients have an autosomal dominant mutation in <i>COL1A1</i> or <i>COL1A2.</i> The severity of the clinical presentation depends upon the effect of the mutation that occurs, having many different phenotypic presentations. In the most severe forms, patients suffer multiple fractures with minimal or no trauma whereas mild forms may only manifest with premature osteoporosis. Attending to the clinical presentation, radiographic findings and the mutation that occurs, 11 different types have been described, with type I and III being the most prevalent. Many treatments have been studied, but none has been found to be curative. The most frecuently used are biphosphonates which try to prevent bone fragility and reduce the number of fractures but none have been approved specifically for use in either children or adults with OI. <h3>Objectives</h3> The aim of the study is to analyse the clinical characteristics of osteogenesis imperfecta (OI) patients followed in our hospital and to evaluate the different treatments used in their management. <h3>Methods</h3> A retrospective study was conducted. All patients diagnosed with OI and seen in the different departments of our hospital were included and analyzed. A database was created, including both clinical and epidemiological data and a descriptive analysis was carried out. <h3>Results</h3> 25 patients with OI are currently being followed up in our hospital and were included. Although most patients were beeing followed in both the Rheumatology (9) and Orthopedic units (9), 4 were being followed by pediatrics, 1 by endocrinology, 1 by internal medicine and 1 by geriatrics. 72% were female (18) with a mean age at diagnosis of 17 years (range: 1 month to 67 years). All of them had had previous fractures before the diagnosis. The number of fractures during their follow-up varied according to the different types of OI, with an average of 6 fractures (range 3-24) per patient and an average of at least 4.16 orthopedic surgeries each. 12/25 patients were diagnosed in the first ten years of life, being the ones that accumulated the highest number of fractures (96 vs. 54). Only 3 patients had family background of OI, all of them beeing type I. Although only 9/25 patients had undergone genetic study, all 3 cases of type III, which is the most severe, debuted in the first decade of life. Phenotipically 14/25 (56%) had short stature and 18/25 (72%) had blue sclerae, being these less frequent in those patients with debut after 20 years of age, of which 57% (4/7) had normal sclerotics. Only 4 patients suffered from dentinogenesis imperfecta (16%) and 3 from otosclerosis and had hearing problems (12%). Regarding the treatment received, 60% of the patients (15/25) were on current treatment with oral calcium and 64% (16/25) with oral vitamin D supplements. On the other hand only 60% of the patients received biphosphonates (4 were beeing treated with risedronate, 7 with pamidronate, and 4 had received both zoledronic and pamidronate during their lives). <h3>Conclusion</h3> Although a rare disease, OI has an important morbimortality in most patients. Severe cases suffer multiple fractures and undergo several orthopedic surgeries during their lifes. Given the high cost of genetic analysis, this is reserved for the most severe cases which tend to debut at younger ages and are mostly type III. Treatment for this condition is not standardized and is generally reserved for type III OI patients, which is one of the most severe types. Biphosphonates, calcium and vitamin D are usually used in order to try to prevent new fragility fractures but in most cases fracture rates remain high despite treatment. <h3>Disclosure of Interests</h3> None declared