Rev Osteoporos Metab Miner. 2010; 2 (3) suplemento: 5-7
Osteoporosis is a global health problem whose importance is going to increase with the aging of the population. It is defined as a systemic disorder of the skeleton characterised by low bone mass and deterioration of the microarchitecture of the bone tissue, with the consequent increase in bone fragility and the greater susceptibility to fractures1. Bone resistance reflects essentially the combination of bone density and bone quality. In turn, the concept of bone quality seeks to integrate all those factors apart from bone mass which determine bone fragility, including the microarchitecture, the degree of turnover, the accumulation of lesions or microfractures, or the degree of mineralisation1,2.
It is a process which is preventable and treatable, but which lacks warning signs prior to the appearance of fractures, leading to the fact of few patients being diagnosed at early stages and treated effectively. Therefore, in some studies it has been confirmed that 95% of patients who presented with a fracture did not have an earlier diagnosis of osteoporosis3.
In 1994 the World Health Organisation (WHO) established some definitions based on measurements of bone mass in the lumbar spine, hip or forearm of white postmenopausal women4. Thus, normal bone mass is considered to be having a bone mineral density (BMD) value higher than -1 standard deviation (SD) in relation to the average for young adults (T-score >-1); osteopenia, having BMD values between -1 and -2.5 SD (T-score between -1 and -2.5); osteoporosis, having BMD values lower than -2.5 SD (T-score lower than -2.5), and osteoporosis is established when, along with the above conditions, are associated one or more fragility fractures (Table 1). It is also possible to consider the Z-score in groups of patients such as children and young adults, which expresses the bone mass in comparison with that expected in those of equal age and sex5.
In 1995 Melton et al estimated the prevalence of osteoporosis according to the WHO criteria in white women over 50 years of age, which was 15% when measured in the three usual places (spine, hip or wrist) and 30% when measured in all of them6. The prevalence increases with age from 15% for the ages between 50 and 59 years, up to a prevalence greater than 80% for women aged over 80 years of age7. According to data from the NHANES III study, in men over 50 years of age, the prevalence of osteoporosis is 8%8.
In Spain, it is calculated that 2 million women and 800,000 men have oseteoporosis, and a study of Díaz Curial et al., in which DXAs were carried out on 1,305 Spanish women between 20 and 80 years of age found a prevalence of osteoporosis in women over 50 years of age of 26.07% (95% CI, 22.57-29.57%)9. Studies in men indicate that the prevalence is 8.1% in those older than 50 years of age10, increasing with age to 11.3% in those over 70 years of age11.
The most direct consequence of osteoporosis is an increase in fragility fractures. Osteoporotic fractures are those located in zones of low BMD, or those which happen after falling over. The presence of fragility fractures is associated with a higher risk of having new osteoporotic fractures, as well as an increase in mortality and a reduction in the quality of life in men and women12. Osteoporotic fractures can be present in multiple locations, but fractures of the proximal extremity of the femur, distal radius and vertebrae are considered to be typically osteoporotic – the last being the most frequent.
In general, osteoporosis has been evaluated by measuring the BMD, which has a direct correlation with bone resistance, and which constitutes a good parameter for the prediction of risk of fracture. However, BMD is not the only parameter which predicts the risk of fracture, since there are also other significant factors such as age (it increases with age), sex (higher in women), race (higher in northern European countries) and concomitant diseases. Nowadays, to decide when to initiate treatment for osteoporosis not only is BMD evaluated, but also the individualised absolute risk of fracture at 5-10 years, incorporating risk factors independent of BMD such as age, sex, weight, previous fractures, family antecedence of fractures, smoking, consumption of glucocorticoids, intake of alcohol, and others13.
Osteoporosis in men represents a significant and growing health problem which is underdiagnosed in the general population. It is characterised as having a higher morbimortality than in women and a higher prevalence of secondary osteoporosis. Thus, in men younger than 70 years of age with osteoporosis, between 40 and 60% have secondary osteoporosis. The most significant causes, quantitatively, are those associated with excess alcohol, that induced by glucocorticoids and primary or secondary hypogonadism.
For little known reasons, hospital mortality due to fracture of the hip and vertebrae in men is double that in women (10% as opposed to 4.7%) and mortality in the year of fracture is also higher in men compared to women (35-37% compared to 28%). In addition, after a low trauma fracture the relative risk of another fracture is also higher in men (RR: 3.4; CI 95%: 2.68-4.48) in comparison with women (RR: 1.95; CI 95%: 1.7-2.25), and the probability of being studied or treated after a hip fracture is lower in men (4.5%) than in women (49.5%)14-18. Some authors postulate that the higher prevalence of comorbidities, and the lower level of therapeutic care observed in men with a fragility fracture could explain, in part, this extra morbimortality.
The prevalence of vertebral fracture is difficult to establish due to there being no consensus regarding the radiological definition of the deformities, and to the fact that its presence is usually asymptomatic. Between 20 and 25% of women over 50 years of age will have a secondary vertebral fracture due to osteoporosis, according to data from European studies. Vertebral fractures are rarely present in those younger than 50 year of age but increase exponentially with age19-21. The annual incidence is considered to be 1% in women of 65 years, 2% in those of 75 years, and 3% in those over 80 years. In men over 50 years of age it is from 5.7 to 6.8/1,000 people per year, which equates to approximately half of that observed in women22. Vertebral deformities in lumbar and dorsal spinal X-rays are three time more frequent than hip fractures, and only a third of vertebral fractures require medical attention.
In European population studies such as the European Prospective Osteoporotic Study (EPOS) and the European Vertebral Osteoporotic Study (EVOS), at 75-79 years of age the incidence of vertebral fractures is 13.6/1,000 people per year for men and 29.3/1,000 people per year for women, and the global incidence by age is 10.7/1,000 people per year in women and 5.7/1,000 people per year in men23-24. After a vertebral deformity there is a 7- to 10-fold increase in new vertebral deformities, and the presence of a previous vertebral deformity predicts an incidence of hip fracture with a risk quotient of 2.8-4.5, and this increases with the number of vertebral deformities25-27. (Figure 1).
Proximal femoral fracture
Hip fractures are considered the most significant osteoporotic fractures due to their associated high morbimortality. In patients with this type of fracture fewer than 50% have complete recuperation, 25% go on to require home care and 20% will require continuing support after the fracture.
Hip fractures are more frequent in women, with a female/male ratio of 3 to 1. The most frequent age for their occurrence is between 75 and 80 years. The incidence of hip fracture increases with age, increasing exponentially from 50 years, their incidence in people younger than 35 years being 2/100,000 and 3,000/100,000 in those over 85 years of age28.
Distal radius fracture
Fracture of the distal third of the radius is more frequent in women, with a female-male ratio of 4 to 1. In women, these fractures are more frequent in the perimenopause, and their incidence increases rapidly through menopause before stabilising at 65 years. In males the incidence remains practically constant with age.
This type of fracture only requires hospitalisation in less than 20% of cases, but increases by 50% the risk of hip fracture29,30.
Osteoporosis should be considered as a real public health problem which justifies the implementation of preventative measures and efficacious therapies. Hence, the primary objective should be to prevent the first fracture and to preserve the integrity of the bone, increasing bone mass and improving bone quality.
1. NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis and Therapy. JAMA 2001; 285:785-95.
2. Sociedad Española de Investigación Ósea y Metabolismo Mineral. Guías de práctica clínica en la osteoporosis postmenopáusica, glucocorticoidea y del varón. Rev Clin Esp 2008;208(Supl 1)1:1-24.
3. Castel H, Bonneth DY, Sherf M, Liel Y. Awareness of osteoporosis and compliance with management guidelines in patients with newly diagnosed low-impact fractures. Osteoporos Int 2001;12:7559-64.
4. World Health Organization. Assesment of fracture risk and its application to screening for postmenopausal osteoporosis. WHO. Technical report series. Ginebra. Suiza 1994.
5. Lewiecki EM, Watts N, Mc Klung M, Petak S, Bachrak L, Sheperd J, et al. Official Positions of the International Society for Clinical Densitometry. J Clin Endocrinol Metab 2004;89:3651-5.
6. Melton LJ 3rd. How many women have osteoporosis now? J Bone Miner Res 1995;10:175-7.
7. Rosen CJ. Postmenopausal osteoporosis. N Eng J Med 2005;353:595-603.
8. Looker AC, Orwell ES, Johnston CC Jr, Lindsay RL, Wahner HW, Dunn WL, et al. Prevalence of low femoral bone density in older U.S. adults from NHANES III. J Bone Miner Res 1997;12:1761-8.
9. Díaz Curiel M, García JJ, Carrasco JL, Honorato J, Pérez Cano R, Rapado A, et al. Prevalencia de osteoporosis determinada por densitometría en la población femenina española. Med Clin (Barc) 2001;116:86-8.
10. Naves M, Díaz-López JB, Gómez C, Rodríguez-Rebollar A, Serrano-Arias M, Cannata-Andía JB. Prevalence of osteoporosis in men and determinants of changes in bone mass in a non-selected Spanish population. Osteoporos Int 2005;16:603-9
11. Diaz Curiel M, Carrasco de la Peña JL, Honorato Perez J, Perez Cano R, Rapado A, Ruiz Martinez I. Study of bone mineral density in lumbar spine and femoral neck in a Spanish population. Multicentre Research Project on Osteoporosis. Osteoporos Int 1997;7:59-64.
12. Kanis JA, Odén A, Johnell O, De Laet C, Jonson B, Oglesby AK. The components of excess mortality after hip fractures. Bone 2003;32:468-73.
13. Kanis JA, Johnell O, Oden A, Dawson A, De Late, Jonsson B. Ten years probabilities of osteoporotic fractures according to BMD and diagnostic thresholds. Osteoporos Int 2001;12:989-95.
15. Center JR, Nguyen TV, Schneider D, Sambrrook PN, Eisman JA. Mortality after all major types of osteoporosis fracture in men and woman: an observational study. Lancet 1999;353:878-82.
16. Jiang HX, Majumdar SR, Dick DA, Moreau M, Raso J, Otto DD, et al. Development and initial validation of a risk score for predicting in-hospital and 1-year mortality in patients with hip fracture. J Bone Miner Res 2005;20.494-500.
17. Diamond TH, Thornley SW, Sekel R, Smerdely P. Hip fracture in elderly men: prognostic factors and outcomes. Med J Aust 1997;167:404-5.
18. Bliuc D, Nguyen ND, Milch VE, Nguyen TV, Eisman JA, Center JR. Mortality risk associated with low-trauma osteoporotic fracture and subsequent fracture in men and women. JAMA 2009;301:513-21.
19. Chrischiller EA, Butter CD, Davis CS, Wallace RB. A model of lifetime osteoporosis. Arch Inter Med 1991;151:2026-32.
20. Cooper C, Atkinson EJ, O´Fallon WM, Melton LJ III. Incidence of clinically diagnosed vertebral fractures: A population-based study in Rochester, Minnesota. J Bone Miner Res 1992;7:221-7.
21. Roy DK, O´Neill TV, Finn JD, Lunt M, Silman AJ, Felsenberg D, et al. Determinants of incident vertebral fracture in men and women: Results from the European Prospective Osteoporosis Study. Osteopor Int 2003;14:19-26.
22. Felsenberg D, Silman AJ, Lunt M, Armbrecht G, Ismail AA, Finn JD, et al. Incidence of vertebral fracture in Europe: results from the European Prospective Osteoporosis Study (EPOS). J Bone Miner Res 2002; 17:716-24.
23. The European Prospective Osteoporosis Study (EPOS) Group. Incidence of vertebral fracture in Europe: results from the European Prospective Osteoporosis Study (EPOS). J Bone Miner Res 2002;17:716-24.
24. Ismail AA, Cooper C, Felsenberg D, Varlow J, Kanis JA, Silman AJ, et al. Number and type of vertebral deformities: epidemiological characteristics and relation to back pain and height loss. European Vertebral Osteoporosis Study Group. Osteoporos Int. 1999;9:206-13.
25. Ross PD, Davis JW, Epstein RS, Wasnich RD. Pre-existing fractures and bone mass predict vertebral fracture incidence in women. Ann Intern Med 1991;114:919-23.
26. Ismail AA, Cockerill W, Cooper C, Finn JD, Abendroth K, Parisi G, et al. Prevalent vertebral deformity predicts incident hip though not distal forearm fracture: Results from the European Prospective Osteoporosis Study. Osteoporos Int 2001:12;85-90.
27. O’Neill TW, Felsenberg D, Varlow J, Cooper C, Kanis JA, Silman AJ. The prevalence of vertebral deformity in European men and women: the European Vertebral Osteoporosis Study. J Bone Miner Res. 1996;11:1010-8.
28. Cooper C, Campion G, Melton JL III. Hip fractures in the elderly: a world wide projection. Osteoporos Int 2001;12:136-9.
29. Honkanen RJ, Honkanen K, Kroger H, Alvaha E, Tuppurainen M, Saarikoshi S. Risk factors for perimenopausal distal forearm fracture. Osteopor Int 2000;11:265-70.
30. Cooper C. Epidemiology of osteoporosis. Osteoporos Int 1999;9:2-8.