Original Full Length Article A United Kingdom perspective on the relationship between body mass index (BMI) and bone health: A cross sectional analysis of data from the Nottingham Fracture Liaison Service Terence Ong a, ⁎, Opinder Sahota a , Wei Tan b , Lindsey Marshall c a Department of Healthcare for Older People, Queens Medical Centre, Nottingham NG7 2UH, UK b Nottingham Clinical Trials Unit, University of Nottingham, Queens Medical Centre, Nottingham NG7 2UH, UK c Department of Trauma and Orthopaedics, Queens Medical Centre, Nottingham NG7 2UH, UK abstract article info Article history: Received 30 August 2013 Revised 29 October 2013 Accepted 24 November 2013 Available online 28 November 2013 Edited by: N. Guanabens Keywords: Obesity Body mass index Bone fractures Bone fragility Bone density Osteoporosis Objectives: This study examines the relationship between high BMI, a diagnosis of osteoporosis and low trauma fractures. Method: This is a cross sectional analysis using data collected from the Nottingham Fracture Liaison Service. A total of 4288 participants with a low trauma fracture from 1 January 2007 to 31 August 2012 were analysed. Logistic regression adjusted for potential confounders was used investigate osteoporosis and BMI. Fracture types were compared between those who were obese and non-obese. Results: A total of 30% (1285) were obese. Prevalence of osteoporosis was 13.4%, 24.9%, and 40.4% in the obese, overweight and normal category respectively. Being obese has an odds ratio of 0.23 (95% CI 0.19–0.28, p b 0.01) of having osteoporosis compared to a normal BMI category. When variable BMI cut offs were used (BMI 25, 30 and 35) to calculate the positive predictive value of patients not having osteoporosis, it was 80.5%, 86.3% and 88.3%. Examining fracture types, obese patients when compared with the non-obese category, were more likely to fracture their ankle (OR 1.48, p b 0.01) and upper arm (OR 1.48, p b 0.001), but were less likely to fracture their wrist (OR 0.65, p b 0.001). In the elderly (N 70 years), obesity no longer influenced ankle or wrist fractures but there is an increased risk of upper arm fractures (OR 1.46, p = 0.005). Conclusion: Higher BMD in obesity is not protective against fractures as there are a significant number of fractures in this group which may be due to body habitus, mechanism of injury and the effect of adiposity on bone. A low trauma osteoporotic fracture will need to be redefined in light of these findings. © 2013 Elsevier Inc. All rights reserved. Introduction Obesity and osteoporosis are two major conditions that are highly prevalent with significant clinical and public health implication [1–4]. The World Health Organisation defines obesity as abnormal or excessive fat accumulation that presents a risk to health. The body mass index (BMI) is a simple way of measuring one's degree of obesity. A BMI of more than 25 kg/m 2 is considered overweight and more than 30 kg/m 2 as obese [1]. A recent health report in England has shown a rise in the prevalence of obesity in adults from 13% to 24% in men; and 16% to 26% in women in almost 20 years [2]. It is projected that by 2025, 47% of men and 36% of women in England will be obese costing the National Health Service an estimated £21.5 billion in treating disease attributed to obesity [3]. Osteoporosis is a progressive, skeletal condition characterised by low bone mass and micro-architectural dete- rioration in bone tissue with a consequent increase in bone fragility and susceptibility to fracture [4]. Similar to obesity, the prevalence of osteoporosis and osteoporotic fractures is expected to rise due to an aging population [5]. It is estimated that by 2050, there will be a 135% and 57% rise in the numbers of hip and vertebral fractures in Europe [6]. Low BMI has been recognised as a risk factor for low BMD and fragil- ity fracture. A recent meta-analysis described an inverse and non-linear relationship between BMI and fracture risk. There was an increasing fracture risk with decreasing units of BMI b 25 kg/m 2 , but the fracture risk reduction was less above this BMI [7]. This less straightforward re- lationship is due to the complex interaction between the mechanical and hormonal factors in obesity on bones. A larger BMI, as expected, confers greater mechanical loading on bone which increases its BMD to accommodate the heavier load [8] and correlates to higher levels of adipose tissue that play an important role in oestrogen production. Obe- sity is also associated with hyperinsulinaemia due to a degree of insulin resistance and low-grade chronic inflammatory state with higher levels of proinflammatory cytokines These effects mediate at the cellular level leading to bone resorption and bone loss [9–12]. This complex relation- ship is perhaps the reason that despite the higher BMD obtained in those with higher BMI, it does not always translate into lower fracture risk and that studies so far on obesity and bone health have yielded Bone 59 (2014) 207–210 ⁎ Corresponding author. Fax: +44 115 947 9947. E-mail address: terenceong@doctors.org.uk (T. Ong). 8756-3282/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.bone.2013.11.024 Contents lists available at ScienceDirect Bone journal homepage: www.elsevier.com/locate/bone