The population-based prevalence of osteoporotic vertebral fracture and densitometric osteoporosis in postmenopausal women over 50 in Valencia, Spain (the FRAVO Study)
Introduction
Osteoporosis is the most prevalent bone disease today. However, since it is asymptomatic, it may not be diagnosed until a clinical fracture has occurred. The gold standard to diagnose osteoporosis is the measurement of bone mineral density (BMD) with dual-energy X-ray absorptiometry (central DXA) [1]. Because of the asymptomatic nature of the disease and the costs and difficulties involved in conducting population-based studies, little is known of its prevalence in specific populations. In Spain, the only published population-based study of the prevalence of osteoporosis detected with central DXA was conducted 20 years ago [2].
Although the risk of fracture is higher in patients with a low bone mass, the best predictor of an osteoporotic fracture is a previous fracture either in the vertebrae or in the hips [3]. Hence, 20% of women who have had a recent vertebral fracture will have a new fracture within a year [4]. Having had one or more vertebral fractures has been related to poorer quality of life [5], [6] and higher long-term mortality [7], [8]. Fractures of the vertebrae, the most frequent of osteoporotic fractures, are underdiagnosed and undertreated [9], [10]. Simple radiology of the thoracic and lumbar spine, an accessible and easy procedure, is the most useful examination for diagnosing vertebral fractures [11]. Recently, morphometric X-ray absorptiometry has shown good concordance with conventional X-ray and could be used as a diagnostic tool saving time and minimizing financial costs and the radiation dose to the patients. However, X-ray of the spine is still the only approved technique for the diagnosis of vertebral fracture by the US Food and Drug Administration (FDA). To reduce variability in the interpretation of these images, standardized techniques such as the Genant method are used [12]. The European Vertebral Osteoporotic Study (EVOS) [13] has found a prevalence of vertebral fracture in women over the age of 50 of between 8% and 21%, depending on the definition of vertebral fracture adopted. The only population-based study published in Spain was part of the EVOS and was performed on women over the age of 50 from the region of Asturias in 1996. It reports a vertebral fracture prevalence of between 13.7% and 27.2% depending on the radiological criteria used [14].
Both osteoporosis and the presence of vertebral fractures are important features when evaluating the risk of a new fracture anywhere in the skeleton. However, in Spain as in other countries, little is known of the prevalence of these risks. The FRAVO study (Fractura vertebral osteoporótica y factores de riesgo asociados en Valencia; Osteoporotic Vertebral Fracture and Associated Risk Factors in Valencia) was conducted to estimate the prevalence of osteoporotic vertebral fracture and densitometric osteoporosis in postmenopausal women over the age of 50 in the city of Valencia, Spain.
Section snippets
Design
This was a population-based cross-sectional study conducted between February 2006 and March 2007.
Population and sample
The study's population was postmenopausal women over the age of 50 living in the city of Valencia, Spain. Exclusion criteria were (1) cognitive impairment considered by the interviewer as an impediment to answering the questionnaire, (2) a physical impediment preventing a woman from going to the radiology centre by her own means, (3) race other than Caucasian, and (4) unwillingness to participate in
Results
Of the 1758 women invited to participate in the study (Fig. 1), 1314 confirmed receipt of the letter (74.7%), and of these, 76 (5.8%) presented at least one of the exclusion criteria. Of the 1238 remaining candidates, 152 declined to participate without providing any explanation; 106 declined because they felt they were receiving adequate care from their own doctors and would not obtain any benefit from participating in the study; and a further 113 declined for miscellaneous reasons (family
Discussion
The results of this study show that in post-menopausal women over the age of 50 in Valencia there is a 21.3% prevalence of vertebral fracture (9.7% when only moderate–severe fractures are taken into account). However, only 1.5% of the women with fractures expressed awareness of their condition. The prevalence of densitometric osteoporosis in the population of post-menopausal women over 50 is 31.8%. The fracture estimates are somewhat lower than the 27.2% (17.1% when considering moderate–severe
Funding
Funded by the General Directorate for Health Organization, Evaluation and Research (Project 0018/2005) and the General Directorate for Public Health of the Ministry of Health of the Autonomous Government of Valencia, and a nonconditioned research grant from Sanofi-Aventis.
Conflict of interest
None of the sponsors played any role in the design of the study, the collection, analysis or interpretation of data, the writing of the manuscript or in the decision to submit it for publication. JSG and SP have received research grants from various pharmaceutical companies, and fees for participation in scientific meetings sponsored by pharmaceutical companies.
Acknowledgments
We are grateful to Manuel Escolano-Puig, General Director of Public Health of the Autonomous Government of Valencia, for his support of this project. The radiology departments of the Dr. Peset and La Fe University Hospitals and the Valencia School of Health Studies also provided invaluable support in conducting our work.
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