Anthropometry, physical activity and hip fractures in the elderly

Associations of abdominal obesity with different types of bone fractures in adults: A systematic review and dose-response meta-analysis of prospective cohort studies

Findings on the association between abdominal obesity and hip fracture were summarized in a meta-analysis in 2017; however, no study has examined the dose-response association between abdominal fat indices and hip fracture. Also, we found no meta-analysis investigating other types of bone fractures including any vertebral fractures in relation to abdominal obesity. Therefore, the present systematic review and dose-response meta-analysis of prospective cohort studies were conducted to examine the association between abdominal obesity and different types of bone fractures. A comprehensive literature search was done by searching PubMed, Scopus, Web of Science, and Google Scholar until October 2021. In total, 23 articles from prospective cohort studies with a total sample size of 3,456,631 participants were included. During the follow-up periods ranging between 4 and 26 years, 137,989 cases of bone fracture were recorded. After comparing the highest and lowest categories of abdominal fat indices, the summary relative risks (RRs) of any, hip, and vertebral fractures were 0.99 (95% CI: 0.81-1.20), 1.09 (95% CI: 0.82-1.43), and 1.18 (95% CI: 1.05-1.33), respectively, indicating a significant positive association between abdominal obesity and risk of vertebral fracture. In the non-linear dose-response analysis, abdominal obesity based on the waist-to-hip ratio (WHR) was positively associated with an increased risk of hip fracture from 0.7 to 1.1 units of WHR. In the linear analysis, a 10 cm increase in waist circumference (WC) was associated with a 3% higher risk of vertebral fracture. We found no other dose-response association for other types of bone fractures. In conclusion, abdominal obesity may be associated with a higher risk of hip and vertebral fractures.

Early-life famine exposure, adulthood obesity patterns, and risk of low-energy fracture

Malnutrition in early life increases the risk of osteoporosis, but the association of early-life undernutrition combined with adulthood obesity patterns with low-energy fracture remains unknown. This study included 5323 community-dwelling subjects aged ⩾40 years from China. Early-life famine exposure was identified based on the participants' birth dates. General obesity was assessed using the body mass index (BMI), and abdominal obesity was evaluated with the waist-to-hip ratio (WHR). Low-energy fracture was defined as fracture occurring after the age of ⩾40 typically caused by falls from standing height or lower. Compared to the nonexposed group, the group with fetal, childhood, and adolescence famine exposure was associated with an increased risk of fracture in women with odds ratios (ORs) and 95% confidence intervals (CIs) of 3.55 (1.57-8.05), 3.90 (1.57-9.71), and 3.53 (1.05-11.88), respectively, but not in men. Significant interactions were observed between fetal famine exposure and general obesity with fracture among women (P for interaction = 0.0008). Furthermore, compared with the groups with normal BMI and WHR, the group of women who underwent fetal famine exposure and had both general and abdominal obesity had the highest risk of fracture (OR, 95% CI: 3.32, 1.17-9.40). These results indicate that early-life famine exposure interacts with adulthood general obesity and significantly increases the risk of low-energy fracture later in life in women.

General and abdominal obesity operate differently as influencing factors of fracture risk in old adults

To infer the causality between obesity and fracture and the difference between general and abdominal obesity, a prospective study was performed in 456,921 participants, and 10,142 participants developed an incident fracture with follow-up period of 7.96 years. A U-shape relationship was observed between BMI and fracture, with the lowest risk of fracture in overweight participants. The obesity individuals had higher fracture risk when BMD was adjusted, and the protective effect of moderate-high BMI on fracture was mostly mediated by bone mineral density (BMD). However, for abdominal obesity, the higher WCadjBMI (linear) and HCadjBMI (J-shape) were found to be related to higher fracture risk, and less than 30% of the effect was mediated by BMD. By leveraging genetic instrumental variables, it provided additional evidences to support the aforementioned findings. In conclusion, keeping moderate-high BMI might be of benefit to old people in terms of fracture risk, whereas abdominal adiposity might increase risk of fracture.

Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study

Poor physical function and body composition my partly predict the risk of falls leading to fracture regardless of bone mineral density.

INTRODUCTION

To examine the relationship between body composition, physical function, and other markers of health with hip fractures in older community-dwelling Icelandic adults.

METHODS

A prospective cohort of 4782 older adults from the AGES-Reykjavik study. Baseline recruitment took place between 2002 and 2006, and information on hip fractures occurring through 2012 was extracted from clinical records. Using multivariate regression analyses, baseline measures of bone health, physical function, and body composition were compared between those who later experienced hip fractures and to those who did not. Associations with the risk of fractures were quantified using Cox regression.

RESULTS

Mean age was 76.3 years at baseline. After adjustment for age, regression showed that male hip fracture cases compared with non-cases had (mean (95% confidence interval)) significantly lower thigh muscle cross-sectional area - 5.6 cm2 (- 10.2, - 1.1), poorer leg strength - 28 N (- 49, - 7), and decreased physical function as measured by longer timed up and go test 1.1 s (0.5, 1.7). After adjustment for age, female cases had, compared with non-cases, lower body mass index - 1.5 kg/m2 (- 2.1, - 0.9), less lean mass - 1.6 kg (- 2.5, - 0.8), thigh muscle cross-sectional area - 4.4 cm2 (- 6.5, - 2.3), and worse leg strength - 16 N (- 25, - 6). These differences largely persisted after further adjustment for bone mineral density (BMD), suggesting that body composition may contribute to the risk of fracture independent of bone health. When examining the association between these same factors and hip fractures using Cox regression, the same conclusions were reached.

CONCLUSIONS

After accounting for age and BMD, older adults who later experienced a hip fracture had poorer baseline measures of physical function and/or body composition, which may at least partly contribute to the risk of falls leading to fracture.

Mediterranean diet and hip fracture incidence among older adults: the CHANCES project

The association between adherence to Mediterranean diet (MD) and hip fracture incidence is not yet established. In a diverse population of elderly, increased adherence to MD was associated with lower hip fracture incidence. Except preventing major chronic diseases, adhering to MD might have additional benefits in lowering hip fracture risk.

INTRODUCTION

Hip fractures constitute a major public health problem among older adults. Latest evidence links adherence to Mediterranean diet (MD) with reduced hip fracture risk, but still more research is needed to elucidate this relationship. The potential association of adherence to MD with hip fracture incidence was explored among older adults.

METHODS

A total of 140,775 adults (116,176 women, 24,599 men) 60 years and older, from five cohorts from Europe and the USA, were followed-up for 1,896,219 person-years experiencing 5454 hip fractures. Diet was assessed at baseline by validated, cohort-specific, food-frequency questionnaires, and hip fractures were ascertained through patient registers or telephone interviews/questionnaires. Adherence to MD was evaluated by a scoring system on a 10-point scale modified to be applied also to non-Mediterranean populations. In order to evaluate the association between MD and hip fracture incidence, cohort-specific hazard ratios (HR), adjusted for potential confounders, were estimated using Cox proportional-hazards regression and pooled estimates were subsequently derived implementing random-effects meta-analysis.

RESULTS

A two-point increase in the score was associated with a significant 4% decrease in hip fracture risk (pooled adjusted HR 0.96; 95% confidence interval (95% CI) 0.92-0.99, p_{heterogeneity} = 0.446). In categorical analyses, hip fracture risk was lower among men and women with moderate (HR 0.93; 95% CI 0.87-0.99) and high (HR 0.94; 95% CI 0.87-1.01) adherence to the score compared with those with low adherence.

CONCLUSIONS

In this large sample of older adults from Europe and the USA, increased adherence to MD was associated with lower hip fracture incidence.

Abdominal obesity and risk of hip fracture: a meta-analysis of prospective studies

We conducted a meta-analysis to qualitatively summarize the evidence of the association between abdominal obesity and hip fracture risk. The results indicated that abdominal obesity as measured by waist circumference and waist-hip ratio might be associated with an increased risk of hip fracture.

INTRODUCTION

Epidemiological investigations evaluating the association of abdominal obesity with hip fracture risk have yielded conflicting results. Therefore, a meta-analysis was conducted to qualitatively summarize the evidence of the associations between waist circumference, waist-hip ratio, and hip circumference and the risk of hip fracture, respectively.

METHODS

PubMed, Embase, and Web of Science were searched for relevant articles published up to March 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated with a random-effects model. Dose-response relationship was assessed by restricted cubic spline.

RESULTS

Seven studies involving 180,600 participants for hip circumference, six studies involving 199,828 participants for waist-hip ratio, and five studies involving 170,796 participants for waist circumference were finally included in this meta-analysis. The combined RRs with 95% CIs of hip fracture for the highest versus lowest category of waist circumference, waist-hip ratio, and hip circumference were 1.58 (95% CI 1.20-2.08), 1.32 (95% CI 1.15-1.52), and 0.87 (95% CI 0.74-1.02), respectively. For dose-response analysis, a nonlinear relationship was found (P _nonlinearity < 0.001) between waist circumference and the risk of hip fracture, and a linear relationship (P _nonlinearity = 0.911) suggested that the risk of hip fracture increased about 3.0% (1.03 (1.01-1.04)) for each 0.1 unit increment of waist-hip ratio.

CONCLUSIONS

This meta-analysis suggested that abdominal obesity as measured by waist circumference and waist-hip ratio might be associated with an increased risk of hip fracture. From a public health perspective, indicators of abdominal obesity may be usable predictors of hip fracture risk.

Abdominal Obesity and Risk of Hip Fracture: A Systematic Review and Meta-Analysis of Prospective Studies

Data on the association between general obesity and hip fracture were summarized in a 2013 meta-analysis; however, to our knowledge, no study has examined the association between abdominal obesity and the risk of hip fracture. The present systematic review and meta-analysis of prospective studies was undertaken to summarize the association between abdominal obesity and the risk of hip fracture. We searched online databases for relevant publications up to February 2017, using relevant keywords. In total, 14 studies were included in the systematic review and 9 studies, with a total sample size of 295,674 individuals (129,964 men and 165,703 women), were included in the meta-analysis. Participants were apparently healthy and aged ≥40 y. We found that abdominal obesity (defined by various waist-hip ratios) was positively associated with the risk of hip fracture (combined RR: 1.24, 95% CI: 1.05, 1.46, P = 0.01). Combining 8 effect sizes from 6 studies, we noted a marginally significant positive association between abdominal obesity (defined by various waist circumferences) and the risk of hip fracture (combined RR: 1.36; 95% CI: 0.97, 1.89, P = 0.07). This association became significant in a fixed-effects model (combined effect size: 1.40, 95% CI: 1.25, 1.58, P < 0.001). Based on 5 effect sizes, we found that a 0.1-U increase in the waist-hip ratio was associated with a 16% increase in the risk of hip fracture (combined RR: 1.16, 95% CI: 1.04, 1.29, P = 0.007), whereas a 10-cm increase in waist circumference was not significantly associated with a higher risk of hip fracture (combined RR: 1.13, 95% CI: 0.94, 1.36, P = 0.19). This association became significant, however, when we applied a fixed-effects model (combined effect size: 1.21, 95% CI: 1.15, 1.27, P < 0.001). We found that abdominal obesity was associated with a higher risk of hip fracture in 295,674 individuals. Further studies are needed to test whether there are associations between abdominal obesity and fractures at other bone sites.

Height and Risk of Hip Fracture: A Meta-Analysis of Prospective Cohort Studies

The association between height and risk of hip fracture has been investigated in several studies, but the evidence is inconclusive. We therefore conducted this meta-analysis of prospective cohort studies to explore whether an association exists between height and risk of hip fracture. We searched PubMed and EMBASE, Web of Science, and the Cochrane Library for studies of height and risk of hip fracture up to February 16, 2016. The random-effects model was used to combine results from individual studies. Seven prospective cohort studies, with 7,478 incident hip fracture cases and 907,913 participants, were included for analysis. The pooled relative risk (RR) was 1.65 (95% confidence interval (CI): 1.26-2.16) comparing the highest with the lowest category of height. Result from dose-response analysis suggested a linear association between height and hip fracture risk (P-nonlinearity = 0.0378). The present evidence suggests that height is positively associated with increased risk of hip fracture. Further well-designed cohort studies are needed to confirm the present findings in other ethnicities.

Abdominal obesity and hip fracture: results from the Nurses' Health Study and the Health Professionals Follow-up Study

Abdominal obesity might increase fracture risk. We studied the prospective associations between waist circumference, waist-to-hip ratio, and hip fracture. The indicators of abdominal obesity were associated with increased hip fracture risk in women, but not in men. The increased risk was restricted to women with low physical activity.

INTRODUCTION

Low weight is an established risk factor for osteoporosis and hip fracture. However, the association between fat tissue, muscle, and bone is complex, and abdominal obesity might increase fracture risk. We studied the prospective associations between indicators of abdominal obesity and hip fracture in two large US cohorts.

METHODS

At baseline in 1986 and through biennial follow-up, information on hip fracture and potential risk factors was collected in 61,677 postmenopausal women and 35,488 men above age 50. Waist and hip circumferences were reported at baseline and updated twice.

RESULTS

During follow-up, 1168 women and 483 men sustained a hip fracture. After controlling for known risk factors, there was a significant association in women between increasing waist circumference and hip fracture (RR per 10-cm increase 1.13 (95 % CI 1.04-1.23) and between increasing waist-to-hip ratio and hip fracture (RR per 0.1 unit increase 1.14 (95 % CI 1.04-1.23), but these associations were not seen in men. In women, both measures interacted with physical activity. Those in the highest (≥0.90) versus lowest (<0.75) category of waist-to-hip ratio had increased risk of hip fracture if their activity was less than the population median (RR = 1.61, 95 % CI 1.18-2.19) but not if their activity was higher (RR = 1.00, 95 % CI 0.72-1.40). A similar pattern was found for waist circumference.

CONCLUSION

Indicators of abdominal obesity were associated with increased hip fracture risk after controlling for BMI in women. The increased risk was restricted to women with low physical activity. In men, no significant associations were found.

Education, marital status, and risk of hip fractures in older men and women: the CHANCES project

The role of socioeconomic status in hip fracture incidence is unclear. In a diverse population of elderly, higher education was found to be associated with lower, whereas living alone, compared to being married/cohabiting, with higher hip fracture risk. Educational level and marital status may contribute to hip fracture risk.

INTRODUCTION

The evidence on the association between socioeconomic status and hip fracture incidence is limited and inconsistent. We investigated the potential association of education and marital status with hip fracture incidence in older individuals from Europe and USA.

METHODS

A total of 155,940 participants (79 % women) aged 60 years and older from seven cohorts were followed up accumulating 6456 incident hip fractures. Information on education and marital status was harmonized across cohorts. Hip fractures were ascertained through telephone interviews/questionnaires or through record linkage with registries. Associations were assessed through Cox proportional hazard regression adjusting for several factors. Summary estimates were derived using random effects models.

RESULTS

Individuals with higher education, compared to those with low education, had lower hip fracture risk [hazard ratio (HR) = 0.84, 95 % confidence interval (CI) 0.72-0.95]. Respective HRs were 0.97 (95 % CI 0.82-1.13) for men and 0.75 (95 % CI 0.65-0.85) for women. Overall, individuals living alone, especially those aged 60-69 years, compared to those being married/cohabiting, tended to have a higher hip fracture risk (HR = 1.12, 95 % CI 1.02-1.22). There was no suggestion for heterogeneity across cohorts (P heterogeneity > 0.05).

CONCLUSIONS

The combined data from >150,000 individuals 60 years and older suggest that higher education may contribute to lower hip fracture risk. Furthermore, this risk may be higher among individuals living alone, especially among the age group 60-69 years, when compared to those being married/cohabiting.

Análise dos fatores associados a quedas com fratura de fêmur em idosos: um estudo caso-controle

OBJETIVO: Identificar os principais fatores associados a quedas e fraturas de fêmur em idosos. MÉTODOS: Trata-se de estudo caso-controle (um grupo de casos e dois grupos controle) na proporção de 1:1:1, em que foram estudados 135 indivíduos com idade ≥60 anos, pareados por sexo, no período de 2005 a 2012. Os dados foram coletados por meio de entrevistas nos domicílios dos participantes, e realizou-se levantamento de informações em prontuários. Para análise das diferenças entre proporções e médias entre os grupos, empregaram-se o teste qui-quadrado e o teste t Student, respectivamente. Para o estudo da associação entre variáveis, foram realizadas análises univariadas e multivariadas empregando-se regressão logística. Como medida de efeito, foram empregados odds ratio (OR) e seu intervalo de confiança a 95% (IC95%). Em todas as análises, considerou-se um nível de significância de 5%. RESULTADOS: Após análise multivariada, os fatores de proteção contra fratura de fêmur foram: ouvir bem e possuir corrimão nas escadas de suas residências. Os fatores de risco para fratura de fêmur foram: hipertensão arterial sistêmica, sedentarismo e possuir superfície escorregadia na residência. Os fatores de proteção para queda foram: possuir corrimão nas escadas de suas residências, ser portador de osteoporose e depressão. O fator de risco de queda foi o sedentarismo. CONCLUSÃO: As fraturas de fêmur representam importante fator de morbidade em idosos. Conhecer os fatores de risco para fraturas pós-queda em idosos é essencial para o planejamento de ações individuais e coletivas voltadas à prevenção deste agravo e suas consequências. Atividades físicas, planos terapêuticos mais adequados e correção de inadequações nos domicílios desses indivíduos devem ser orientados e incentivados.

Abdominal obesity increases the risk of hip fracture. A population-based study of 43,000 women and men aged 60-79 years followed for 8 years. Cohort of Norway

BACKGROUND

The question as to whether abdominal obesity has an adverse effect on hip fracture remains unanswered. The purpose of this study was to investigate the associations of waist circumference, hip circumference, waist-hip ratio, and body mass index with incident hip fracture.

METHODS

The data in this prospective study is based on Cohort of Norway, a population-based cohort established during 1994-2003. Altogether 19,918 women and 23,061 men aged 60-79 years were followed for a median of 8.1 years. Height, weight, waist and hip circumference were measured at baseline using standard procedures. Information on covariates was collected by questionnaires. Hip fractures (n = 1,498 in women, n = 889 in men) were identified from electronic discharge registers from all general hospitals in Norway between 1994 and 2008.

RESULTS

The risk of hip fracture decreased with increasing body mass index, plateauing in obese men. However, higher waist circumference and higher waist-hip ratio were associated with an increased risk of hip fracture after adjustment for body mass index and other potential confounders. Women in the highest tertile of waist circumference had an 86% (95% CI: 51-129%) higher risk of hip fracture compared to the lowest, with a corresponding increased risk in men of 100% (95% CI 53-161%). Lower body mass index combined with abdominal obesity increased the risk of hip fracture considerably, particularly in men.

CONCLUSION

Abdominal obesity was associated with an increased risk of hip fracture when body mass index was taken into account. In view of the increasing prevalence of obesity and the number of older people suffering osteoporotic fractures in Western societies, our findings have important clinical and public health implications.

Identification of patient profile for treatment

The WHO clinical definition of osteoporosis, based on a measurement of bone mineral density (BMD) by Dual Energy X-ray Absorptiometry, has been used globally since the mid-1990s. However, although this definition identifies those at greatest individual risk of fracture, in the population overall a greater total number of fractures occur in individuals with BMD values above the osteoporosis threshold. The inclusion of clinical risk factors, with or without BMD, in fracture prediction algorithms can improve the identification of individuals at high fracture risk; thus a number of web-based tools have been developed, the most commonly used globally being FRAX(®). In this review, we will discuss the epidemiology of osteoporosis, clinical risk factors for fragility fracture, and how this knowledge is being used to aid risk stratification. Importantly, research is on-going to demonstrate the clinical efficacy and cost-effectiveness of such case-finding strategies.

The effect of spinal curvature on the photogrammetric assessment on static balance in elderly women

BACKGROUND

Involutional changes to the body in elderly patients affect the shape of the spine and the activity of postural muscles. The purpose of this study was to assess the influence of age-related changes in spinal curvature on postural balance in elderly women.

METHODS

The study population consisted of 90 women, with a mean age of 70 ± 8.01 years. Static balance assessments were conducted on a tensometric platform, and posturographic assessments of body posture were performed using a photogrammetric method based on the Projection Moiré method.

RESULTS

The results obtained were analysed using the Spearman's rank correlation coefficient test. We found a statistically significant correlation between body posture and the quality of the balance system response based on the corrective function of the visual system. The shape of the spinal curvature influenced postural stability, as measured by static posturography. Improvement in the quality of the balance system response depended on corrective information from the visual system and proprioceptive information from the paraspinal muscles.

CONCLUSIONS

The sensitivity of the balance system to the change of centre of pressure location was influenced by the direction of the change in rotation of the shoulder girdle and spine. Development of spinal curvature in the sagittal plane and maintenance of symmetry in the coronal and transverse planes are essential for correct balance control, which in turn is essential for the development of a properly proportioned locomotor system.

Relationship of weight, height, and body mass index with fracture risk at different sites in postmenopausal women: the Global Longitudinal study of Osteoporosis in Women (GLOW)

Low body mass index (BMI) is a well-established risk factor for fracture in postmenopausal women. Height and obesity have also been associated with increased fracture risk at some sites. We investigated the relationships of weight, BMI, and height with incident clinical fracture in a practice-based cohort of postmenopausal women participating in the Global Longitudinal study of Osteoporosis in Women (GLOW). Data were collected at baseline and at 1, 2, and 3 years. For hip, spine, wrist, pelvis, rib, upper arm/shoulder, clavicle, ankle, lower leg, and upper leg fractures, we modeled the time to incident self-reported fracture over a 3-year period using the Cox proportional hazards model and fitted the best linear or nonlinear models containing height, weight, and BMI. Of 52,939 women, 3628 (6.9%) reported an incident clinical fracture during the 3-year follow-up period. Linear BMI showed a significant inverse association with hip, clinical spine, and wrist fractures: adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) per increase of 5 kg/m(2) were 0.80 (0.71-0.90), 0.83 (0.76-0.92), and 0.88 (0.83-0.94), respectively (all p < 0.001). For ankle fractures, linear weight showed a significant positive association: adjusted HR per 5-kg increase 1.05 (1.02-1.07) (p < 0.001). For upper arm/shoulder and clavicle fractures, only linear height was significantly associated: adjusted HRs per 10-cm increase were 0.85 (0.75-0.97) (p = 0.02) and 0.73 (0.57-0.92) (p = 0.009), respectively. For pelvic and rib fractures, the best models were for nonlinear BMI or weight (p = 0.05 and 0.03, respectively), with inverse associations at low BMI/body weight and positive associations at high values. These data demonstrate that the relationships between fracture and weight, BMI, and height are site-specific. The different associations may be mediated, at least in part, by effects on bone mineral density, bone structure and geometry, and patterns of falling.

Trends in the incidence of hip fractures

Hip fracture incidence in the capital city of Serbia was assessed over a period of 10 years (2000-2009). Crude annual incidence rates increased significantly for all ages and both sexes (p = 0.002). Age-adjusted rates also showed a steady increase. The mean rate of annual change for age-adjusted rates was 8.6 % (95 %CI 7.5-9.7) in males, 8.0 % (95 %CI 7.4-8.6) in females, and 8.2 % (95 %CI 7.7-8.7) in the total population.

INTRODUCTION

The aim of this study was to estimate the incidence rate and trend of hip fractures in the population of Belgrade, the capital of Serbia.

METHODS

Data sources were the official statistics of the Public Health Institute in Belgrade. The patient's age, gender, residence, hospital admission, and diagnosis were registered for each hospital admission. Population estimates were based on census data from 2002 and on published estimates for the intercensus years. The annual incidence (crude) rates and age- and sex-specific incidence rates were calculated with 95 % confidence intervals (CI) and age-adjusted incidence rates for persons over the age of 50 years were computed.

RESULTS

A significantly increasing trend of crude incidence rates for all ages was observed in males (p = 0.002), females (p = 0.001), and overall (p = 0.002). The proportion of trochanteric fractures rose significantly with age in women (p < 0.0001), whereas it decreased nonsignificantly in men ≥70 years (p = 0.44). The age-adjusted incidence rates (per 100,000 in subjects ≥50 years old) showed a steady increase. The mean rate of annual change for age-adjusted rates was 8.6 % (95 %CI 7.5-9.7) in males, 8.0 % (95 %CI 7.4-8.6) in females, and 8.2 % (95 %CI 7.7-8.7) in the total population.

CONCLUSION

Hip fracture incidence continues to increase. In view of the rapid aging of the population, it is necessary to implement a comprehensive preventive policy in our community.

Obesity and risk of hip fracture in adults: a meta-analysis of prospective cohort studies

Background

Many observational studies assessed the association between obesity and risk of hip fracture in adults, but reported controversial results. Our goal was to evaluate the association between obesity and risk of hip fracture in adults by conducting a meta-analysis of prospective cohort studies.

Methods

Three databases, PubMed, Embase and Web of Science, were searched through May 2012 to identify eligible cohort studies. Either a fixed- or a random-effects model was used to calculate the pooled relative risk (RR) with its 95% confidence interval (95%CI).

Results

Fifteen prospective cohort studies involving a total 3,126,313 participants were finally included into this meta-analysis. Overall, adults with obesity compared with the normal weight group had a significantly decreased risk of hip fracture (RR: 0.66, 95% CI 0.57 to 0.77, P<0.001). Meta-analyses by the adjusted status of RRs also suggested adults with obesity compared with the reference group had a significantly decreased risk of hip fracture (adjusted RR: 0.48, 95% CI 0.39 to 0.58, P<0.001; unadjusted RR: 0.66, 95% CI 0.56 to 0.78, P<0.001). Subgroup analyses by gender suggested individuals with obesity had a significantly decreased risk for developing hip fracture compared with the reference group in both men (RR 0.54, 95% CI 0.48 to 0.60, P<0.001) and women (RR 0.70, 95% CI 0.58 to 0.84, P<0.001). No evidence of publication bias was observed in this meta-analysis.

Conclusions

This meta-analysis of prospective cohort studies suggests that obesity significantly decreases the risk of hip fracture in adults, and obesity is probably a protective factor of hip fracture in adults.