Low BMD is less predictive than reported falls for future limb fractures in women across Europe: results from the European Prospective Osteoporosis Study
Introduction
Aside from major trauma, the occurrence of many limb fractures in those over age 50 is explained by a fall. Those with low bone mineral density (BMD) are at increased risk of fracture as a result of a fall. As argued frequently elsewhere, anticipated risk factors for limb fractures would thus include those associated with both falling and low bone density, including some such as frailty that might be common to both.
In some prospective studies, a decreased bone density has been shown to be an important predictor of future limb fractures. In the Study of Osteoporotic Fractures (SOF), women in the lowest quintile of distal radius BMD had four times the risk of distal forearm fracture and 7.5 times the risk of proximal humerus fracture when compared to those in the highest quintile [1]. In the Dubbo study, there was a 50% increased risk of forearm and wrist fracture per standard deviation reduction in femoral neck BMD, which was observed in both genders [2]. Some retrospective data suggest that low BMD may be of less importance in predicting susceptibility in those aged over 65 [3], while other data support its utility [4]. The data are not entirely consistent with regard to lifestyle risk factors [2], [5], [6], [7], with roles of varying importance for physical inactivity, smoking, body mass, and comorbidity. Some studies have demonstrated a decreased risk of lower limb fracture among the physically active [8], [9], while other studies have shown that the most active persons are at greater risk of an upper limb fracture [1], [10]. Although there is evidence that BMD is important in determining limb fractures, little is known about its relative importance if adjusted for fall risk and other risk factors, especially with data from diverse populations where large variations in BMD and fall risk are to be expected.
We have recently completed a multicenter multinational prospective study of fractures and falls, the European Prospective Osteoporosis Study (EPOS), in which nonspine fractures were identified prospectively over a mean of 3 years and spine fractures over a mean of 3.8 years. In recent papers, we have presented the descriptive epidemiology of the nonspine fractures [11], an analysis of the contribution of center-specific fall rates to the risk of limb fractures [12], and an evaluation of the contribution of lifestyle, gynecological, and fracture history to the risk of distal forearm fracture [13]. In the present paper, we have taken advantage of the fact that 20 of the 31 participating centers in the EPOS limb fracture study obtained measurements of hip and/or spine BMD. We have analyzed the independent contributions of bone density, falls, and other risk factors for limb fractures with a view to defining their importance for predicting upper and lower limb fractures in European women and men in the 6th to 8th decades of age. We also aimed to describe the relative contributions of center-specific BMD vs. center-specific fall rates in explaining variation in fracture rates between centers after adjusting for the risk factors measured at the individual level.
Section snippets
Subjects
The subjects included in the analysis were participants in the European Prospective Osteoporosis Study (EPOS), which was a follow-up study on subjects initially recruited to the European Vertebral Osteoporosis Study (EVOS). Detailed methods of the two studies have been reported elsewhere [11], [14], [15]. In brief, stratified sampling was used to recruit men and women aged 50 years and over from population registers in 36 European centers. The aim was to recruit equal numbers of men and women
Subjects characteristics
In the 20 centers that contributed data to this analysis, 2451 men, mean age 63.7 (SD = 8.0) years, and 2919 women, mean age 62.8 (SD = 7.7) years, were followed for a median of 3.0 years (range = 0.5–5.4 years), for a total of 16,654 person years (pyrs) of follow-up. Owing to resource constraints, not all centers recruited their target numbers of subjects. Table 1 shows summary statistics for other subject characteristics studied. Bone mineral density was measured at the hip in 2565 (88%)
Discussion
Bone mineral density has been shown to be a predictor of fracture in a number of single center studies. The paper presents data from a multicenter multinational prospective study. In this paper, we present the results of modeling limb fracture risk as a function of BMD after adjusting for the other significant risk factors for fracture described by Silman [13] or Roy et al. [12]. The main result is that bone mineral density appeared to be less important in explaining variations in incidence of
Acknowledgments
The study was financially supported by a European Union Concerted Action Grant under Biomed-1 (BMH1CT920182) and also EU grants C1PDCT925102, ERBC1PDCT 930105 and 940229 and QLK6-CT-2002-00491. The central coordination was also supported by the UK Arthritis Research Campaign, the Medical Research Council (G9321536), and the European Foundation for Osteoporosis and Bone Disease. The EU's PECO program linked to BIOMED 1 funded in part the participation of the Budapest, Warsaw, Prague, Piestany,
References (35)
- et al.
Falls explain between centre differences in the incidence of limb fracture across Europe
Bone
(2002) - et al.
The European spine phantom—a tool for standardization and quality control in spinal bone mineral measurements by DXA and QCT
Eur. J. Radiol.
(1995) - et al.
The relationship among history of falls, osteoporosis, and fractures in postmenopausal women
Arch. Phys. Med. Rehabil.
(2002) - et al.
COLIA1 polymorphism contributes to bone mineral density to assess prevalent wrist fractures
Bone
(2000) - et al.
Risk factors for fractures of the distal forearm and proximal humerus
Am. J. Epidemiol.
(1992) - et al.
Risk factors for proximal humerus, forearm, and wrist fractures in elderly men and women: the Dubbo Osteoporosis Epidemiology Study
Am. J. Epidemiol.
(2001) - et al.
Colles' fracture of the wrist as an indicator of underlying osteoporosis in postmenopausal women: a prospective study of bone mineral density and bone turnover rate
Osteoporos Int.
(1998) - et al.
Bone mineral density predicts non-spine fractures in very elderly women
Osteoporos Int.
(1994) - et al.
Risk factors for wrist fracture: effect of age, cigarettes, alcohol, body height, relative weight, and handedness on the risk for distal forearm fractures in men
Am. J. Epidemiol.
(1994) - et al.
Fractures and lifestyle: effect of cigarette smoking, alcohol intake, and relative weight on the risk of hip and forearm fractures in middle-aged women
Am. J. Public Health
(1988)
Incidence of Colles' fracture in Uppsala. A prospective study of a quarter-million population
Acta Orthop. Scand.
The Tromsø study: physical activity and the incidence of fractures in a middle-aged population
J. Bone Miner. Res.
Physical activity and hip fracture: a population-based case-control study
Int. J. Epidemiol.
Risk factors, falls, and fracture of the distal forearm in Manchester, UK
J. Epidemiol. Community Health
Incidence of limb fracture across Europe: results from the European Prospective Osteoporosis Study (EPOS)
Osteoporos Int.
Risk factors for Colles' fracture in men and women: results from the European prospective osteoporosis study (EPOS)
Osteoporos Int.
The prevalence of vertebral deformity in European men and women: the European vertebral osteoporosis study
J. Bone Miner. Res.
Cited by (0)
- 1
Project coordinators.