AB1078 Abdominal radiographs understimate the prevalence of paget’s disease of bone in a fifht of patients

Background The most frequent skeletal localizations of Paget’s disease of bone (PDB) are the pelvis, lumbar spine and proximal femur. Thus, an x-ray including these locations, such as an abdominal radiograph, allows the identification of the disease with a high probability. However, according to previous studies, only 60 to 90% of the global skeletal affection by PDB is included in the area of an abdominal radiograph [1]. In order toknow with certainty the real prevalence of PDB in any population, usually assessed by abdominal radiographs, we need to know the percentage of patients with PDB without pagetic affection of bones included in an abdominal x-ray. Objectives To estimate the percentage of PBD patients without skeletal affection in the pelvis, lumbar spine and/or proximal femur to assess the underestimation of the prevalence of PDB assessed by abdominal radiographs. Methods Transversal descriptive study based on medical records of 602 patients from the Spanish National PBD Register [2]. We included consecutive patients with a skeletal radionuclide scintigraphy and alkaline phosphatase measurement in the year of the diagnosis. We excluded patients treated with bisphosphonates or calcitonin in the previous five years. A central lecture of scintigraphies was made by expert rheumatologists, who identified the pagetic bones included in an abdominal radiograph and in the whole skeleton. Results 214 (36%) bone scans were analyzed. There were not significant differences (p>0.25) between the included patients and patients from the Register in age, gender and time from diagnosis. The percentage of patients with PDB in the lumbar spine, pelvis and/or proximal femur was 80% (IC 95%: [74%>85%]), without differences by gender. This implies that 1/5 of patients are not diagnosed of PDB if only abdominal x-rays are analyzed. New PDB prevalence estimation in Spain is 1.2% (0.9%>1.6%), being 1.5% (1%>2.1%) in men and 1% (0.7%>1.5%) in women. Figure 1 shows the percentage of patients with pagetic involvement in each area. Conclusions Evaluation by abdominal x-rays underestimates 1/5 of patients with Paget’s disease of bone. According to these data, the prevalence of this disease in Spain is 1.2%. This study provides the clues for estimating the real prevalence of Paget’s disease worldwide. References Gennari L, Di Stefano M, Merlotti D, et al. Prevalence of Paget’s disease of bone in Italy. J Bone Miner Res 2005; 20(10):1845-1850. Guanabens N, Garrido J, Gobbo M, et al. Prevalence of Paget’s disease of bone in Spain. Bone 2008; 43(6):1845-1850. Disclosure of Interest None Declared