Influence of baseline deformity definition on subsequent vertebral fracture risk in postmenopausal women

Prevalent morphometric vertebral fractures as a risk factor for subsequent clinical vertebral fractures after shortfusion surgery in older Japanese women with degenerative spondylolisthesis

STUDY DESIGN

A retrospective cohort study using the Kaplan-Meier method with propensity-score matching.

PURPOSE

To evaluate whether the presence of prevalent morphometric vertebral fractures (VFs) poses a risk for subsequent clinical VFs after short-fusion surgery in women aged ≥60 years with degenerative spondylolisthesis.

OVERVIEW OF LITERATURE

VFs are common osteoporotic fractures and are associated with a low quality of life. Subsequent VFs are a complication of instrumented fusion in patients with degenerative lumbar disorders. Thus, risk factors for subsequent VFs after fusion surgery must be analyzed. Population-based studies have suggested that prevalent morphometric VFs led to a higher incidence of subsequent VFs in postmenopausal women; however, no studies have investigated whether prevalent morphometric VFs are a risk factor for subsequent VFs after fusion surgery in patients with degenerative spondylolisthesis.

METHODS

The study enrolled a total of 237 older female patients: 50 and 187 patients had prevalent morphometric VFs (VF [+] group) and nonprevalent morphometric VFs (VF [-] group), respectively. The time to subsequent clinical VFs after fusion surgery was compared between the two groups using the Kaplan-Meier method. Moreover, 40 and 80 patients in the VF (+) and VF (-) groups, respectively, were analyzed and matched by propensity scores for age, follow-up duration, surgical procedure, number of fused segments, body mass index, and number of patients treated for osteoporosis.

RESULTS

Kaplan-Meier analysis indicated that the VF (+) group had a higher incidence of subsequent clinical VFs than the VF (-) group, and Cox regression analysis showed that the presence of prevalent morphometric VFs was an independent risk factor for subsequent clinical VFs before matching. Kaplan-Meier analysis demonstrated comparable results after matching.

CONCLUSIONS

The presence of prevalent morphometric VFs may be a risk factor for subsequent clinical VFs in older women with degenerative spondylolisthesis who underwent short-fusion surgery.

Demographic and economic trends in vertebral fracture surgeries throughout the United States

Background

Vertebral fractures, frequently resulting from high-impact trauma to the spine, are an increasingly relevant public health concern. Little is known about the long-term economic and demographic trends affecting patients undergoing surgery for such fractures. This study examines national economic and demographic trends in vertebral fracture surgery in the United States to improve value-based care and health care utilization.

Methods

The National Inpatient Sample (NIS) was queried for patients who underwent surgical treatment of a vertebral fracture (ICD-9-CM-3.53) (excluding kyphoplasty and vertebroplasty) between 1993 and 2015. Demographic data included patient age, sex, income, insurance type, hospital size, and location. Economic data including aggregate charge, aggregate cost, hospital cost, and hospital charge were analyzed.

Results

The number of vertebral fracture surgeries, excluding kyphoplasty and vertebroplasty, increased 461% from 3,331 in 1993 to 18,675 in 2014, while inpatient mortality increased from 1.9% to 2.5%.The mean age of patients undergoing vertebral fracture surgeries increased from 42 in 1993 to 53 in 2015. The aggregate cost of surgery increased from $189,164,625 in 2001 to $1,060,866,580 in 2014, a 461% increase.

Conclusions

The significant increase in vertebral fracture surgeries between 1993 and 2014 may reflect an increased rate of fractures, more surgeons electing to treat fractures surgically, or a combination of both. The increasing rate of vertebral fracture surgery, coupled with increasing hospital costs and mortality, signifies that the treatment of vertebral fractures remains a challenging issue in healthcare. Further research is necessary to determine the underlying cause of both the increase in surgeries and the increasing mortality rate.

The cumulative incidence of and risk factors for morphometric severe vertebral fractures in Japanese men and women: the ROAD study third and fourth surveys

This population-based cohort study with a 3-year follow-up revealed that the annual incidence rates of vertebral fracture (VF) and severe VF (sVF) were 5.9%/year and 1.7%/year, respectively. The presence of mild VF at the baseline was a significant risk factor for incident sVF in participants without prevalent sVF.

INTRODUCTION

This study aimed to estimate the incidence of morphometric vertebral fracture (VF) and severe VF (sVF) in men and women and clarify whether the presence of a mild VF (mVF) increases the risk of incident sVF.

METHODS

Data from the population-based cohort study, entitled the Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study, were analyzed. In total, 1190 participants aged ≥ 40 years (mean age, 65.0 ± 11.2) years completed whole-spine lateral radiography both at the third (2012-2013, baseline) and fourth surveys performed 3 years later (2015-2016, follow-up). VF was defined using Genant's semi-quantitative (SQ) method: VF as SQ ≥ 1, mVF as SQ = 1, and sVF as SQ ≥ 2. Cumulative incidence of VF and sVF was estimated. Multivariate logistic regression analyses were performed to evaluate risk factors for incident sVF.

RESULTS

The baseline prevalence of mVF and sVF were 16.8% and 6.0%, respectively. The annual incidence rates of VF and sVF were 5.9%/year and 1.7%/year, respectively. The annual incidence rates of sVF in participants without prevalent VF, with prevalent mVF, and with prevalent sVF were 0.6%/year, 3.8%/year, and 11.7%/year (p < 0.001), respectively. Multivariate logistic regression analyses in participants without prevalent sVF showed that the adjusted odds ratios for incident sVF were 4.12 [95% confident interval 1.85-9.16] and 4.53 [1.49-13.77] if the number of prevalent mVF at the baseline was 1 and ≥ 2, respectively.

CONCLUSIONS

The annual incidence rates of VF and sVF were 5.9%/year and 1.7%/year, respectively. The presence of prevalent mVF was an independent risk factor for incident sVF.

Grade 1 Vertebral Fractures Identified by Densitometric Lateral Spine Imaging Predict Incident Major Osteoporotic Fracture Independently of Clinical Risk Factors and Bone Mineral Density in Older Women

Because prevalent vertebral fracture (VF) is a strong predictor of future fractures, they are important to identify in clinical practice as osteoporosis medications are effective and can be used to reduce fracture risk in postmenopausal women with VF. Lateral spine imaging (LSI) with dual-energy X-ray absorptiometry (DXA) can be used to diagnose VFs accurately but is not widespread in clinical practice. The prognostic value of grade 1 (20% to 25% compression) VFs diagnosed by LSI with DXA has been insufficiently studied. The aim of this study was to determine if grade 1 VF is associated with incident fracture in older women. Sahlgrenska University Hospital Prospective Evaluation of Risk of Bone Fractures (SUPERB) is a population-based study of 3028 older women from Gothenburg, Sweden. Included women were 75 to 80 years of age at baseline, answered questionnaires, and were scanned with DXA (Discovery A, Hologic, Waltham, MA, USA). LSI was used to diagnose VFs, which were classified using the Genant semiquantitative method. Cox regression models were used to estimate the association between VFs at baseline and X-ray-verified incident fractures, with adjustment for confounders. Women with a grade 1 VF (n = 264) or a grade 2-3 VF (n = 349) were compared with women without any fracture (n = 1482). During 3.6 years (median, interquartile range [IQR] 1.5 years) of follow-up, 260 women had any incident fracture and 213 a major osteoporotic fracture (MOF). Women with only grade 1 VF had increased risk of any fracture (hazard ratio [HR] = 1.67; 95% confidence interval [CI] 1.18-2.36) and MOF (HR = 1.86; 95% CI 1.28-2.72). For MOF, this association remained after adjustment for clinical risk factors and femoral neck bone mineral density (BMD). In conclusion, grade 1 VFs were associated with incident MOF, also after adjustment for clinical risk factors and BMD, indicating that all VF identified by DXA should be considered in the evaluation of fracture risk in older women. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research..

Vertebral Morphometry

There is as yet no agreement about the criteria by which to arrive at an imaging diagnosis of a vertebral fracture. Because high-grade fractures result in alterations in vertebral shape, 1 possible avenue of diagnosis has been to quantitate changes in vertebral shape. The result has been a variety of methods for the relative and absolute measurements of vertebral dimensions. Such measurements have also lent themselves to automated computed analysis. The number of techniques reflects the absence of any consensus about the best. The semiquantitative technique proposed by Genant has become the most widely used and has served the field well for comparative purposes. Its use in higher grade fractures has been widely endorsed, if some concepts (e.g., short vertebral height-vertebrae) are at variance with lower grades of fracturing. Vertebral morphometry may be the only recourse in high volume epidemiological and interventional studies.

Osteoporosis: the emperor has no clothes

Current prevention strategies for low-trauma fractures amongst older persons depend on the notions that fractures are mainly caused by osteoporosis (pathophysiology), that patients at high risk can be identified (screening) and that the risk is amenable to bone-targeted pharmacotherapy (treatment). However, all these three notions can be disputed.

PATHOPHYSIOLOGY

Most fracture patients have fallen, but actually do not have osteoporosis. A high likelihood of falling, in turn, is attributable to an ageing-related decline in physical functioning and general frailty.

SCREENING

Currently available fracture risk prediction strategies including bone densitometry and multifactorial prediction tools are unable to identify a large proportion of patients who will sustain a fracture, whereas many of those with a high fracture risk score will not sustain a fracture.

TREATMENT

The evidence for the viability of bone-targeted pharmacotherapy in preventing hip fracture and other clinical fragility fractures is mainly limited to women aged 65-80 years with osteoporosis, whereas the proof of hip fracture-preventing efficacy in women over 80 years of age and in men at all ages is meagre or absent. Further, the antihip fracture efficacy shown in clinical trials is absent in real-life studies. Many drugs for the treatment of osteoporosis have also been associated with increased risks of serious adverse events. There are also considerable uncertainties related to the efficacy of drug therapy in preventing clinical vertebral fractures, whereas the efficacy for preventing other fractures (relative risk reductions of 20-25%) remains moderate, particularly in terms of the low absolute risk reduction in fractures with this treatment.

Prevalence of vertebral fractures and minor vertebral deformities evaluated by DXA-assisted vertebral fracture assessment (VFA) in a population-based study of postmenopausal women: the FRODOS study

Population-based studies performed with vertebral fracture assessment (VFA) morphometric technology are lacking in postmenopausal osteoporosis. In this study, we show a lower than expected prevalence of vertebral fractures, a high prevalence of minor vertebral deformities, and a clear association with clinical and densitometric parameters indicating the usefulness of this approach.

INTRODUCTION

Adequate epidemiological data on the prevalence of vertebral fractures (VF) is essential in studies of postmenopausal osteoporosis. Routine DXA-assisted VFA may be useful to determine the presence of VF. However, population-based studies performed with this technology are lacking. We aimed to assess the prevalence of VF and minor deformities in 2,968 postmenopausal women aged 59-70 years from a population-based cohort.

METHODS

VFA and bone mineral density (BMD) measurements were conducted, and McCloskey criteria (vertebral heights under 3 SD from reference values) confirmed with the Genant method were used to define VF. Additionally, minor vertebral deformities (vertebral heights between -2 and -2.99 SD) were evaluated.

RESULTS

The prevalence of VF was 4.3%, and 17% of the participants had minor vertebral deformities. Low BMD was frequently observed in women with VF, with 4%, and 42% of participants showing osteoporosis and osteopenia. Minor vertebral deformities were observed in nearly 40% of women with VF. Multivariate logistic regression analysis showed that age, history of previous fracture, osteoporotic BMD, receiving anti-osteoporotic treatment, and current use of glucocorticoids were significantly associated with VF.

CONCLUSIONS

Although the VFA approach showed a lower than expected prevalence of VF in our cohort, its association with clinical and densitometric parameters may be useful to identify women at risk for developing fragility fractures and may therefore justify its use in longitudinal studies. The high prevalence of minor vertebral deformities detected in patients with VF indicates the need to evaluate this type of deformity as a risk factor for further skeletal fractures.

Genetic polymorphisms in 11β-hydroxysteroid dehydrogenase type 1 correlate with the postdexamethasone cortisol levels and bone mineral density in patients evaluated for osteoporosis

CONTEXT

Higher physiological cortisol levels may increase the risk of age-related osteoporosis. We hypothesized that common polymorphisms in the cortisol synthesis enzyme 11β-hydroxysteroid dehydrogenase (HSD11B) may cause interindividual variations in cortisol levels and age-related bone loss.

STUDY DESIGN AND PATIENTS

We performed a retrospective study in a cohort of 452 ambulatory patients under evaluation for osteoporosis. We investigated the associations of 16 single-nucleotide polymorphisms (in the HSD11B1 and HSD11B2 genes with a postdexamethasone cortisol (PDC) level and bone mineral density (BMD; primary end points) and fracture risk (secondary end point) in a subgroup of 304 patients. The observed associations with BMD were validated in a subgroup of 148 patients.

RESULTS

The PDC level increased with age (R = 0.274, P < 10(-5), n = 287) and was negatively correlated with BMD at the femoral neck (R = -0.278, P < 10(-5), n = 258). Three genetically linked single-nucleotide polymorphisms (in intron 5 of HSD11B1), rs1000283, rs932335, and rs11811440, were significantly associated with BMD, with rs11811440 having the strongest association. The presence of the minor rs11811440 A allele was correlated with a lower PDC level (R = -0.128, P = .03, n = 304). The A allele was also consistently correlated with a higher spinal BMD in both patient subgroups (R = 0.17, Bonferroni corrected P = .006, n = 452). The correlation with BMD remained significant after adjustment for age, gender, body mass index, and type of osteoporosis and was stronger in patients older than 65 years.

CONCLUSION

Genetic variations in HSD11B1 may affect the physiological cortisol levels and the severity of age-related osteoporosis. Underlying functional mechanisms remain to be elucidated.

Lumbar trabecular bone mineral density distribution in patients with and without vertebral fractures: a case-control study

PURPOSE

The proportion of load transmitted through the lumbar neural arch increases with aging, spinal degeneration, and lordosis, effectively shielding the lumbar vertebral bodies from load. This stress shielding may contribute to bone loss in the vertebral body, leading to increased fracture risk. To test his hypothesis, we performed a study to determine if vertebral body fractures were associated with a higher neural arch/vertebral body volumetric bone mineral density (vBMD) ratio.

METHODS

Trabecular vBMD was calculated by quantitative CT in the L3 vertebral body and neural arch (pars interarticularis) of 36 women with vertebral compression fractures and 39 controls. Neural arch/vertebral body vBMD ratio was calculated, and its relationship to fracture status was determined using linear regression models adjusted for age and body mass index.

RESULTS

Vertebral body trabecular vBMD was lower in fracture cases as compared to controls (mean ± SD, 49.0 ± 36.0 vs. 87.5 ± 36.8 mg/cm(3), respectively; P < 0.001), whereas trabecular vBMD of the neural arch was similar (96.1 ± 57.6 in cases vs. 118.2 ± 57.4 mg/cm(3) in controls; P = 0.182). The neural arch/vertebral body vBMD ratio was significantly greater in the fracture group than in controls (2.31 ± 1.07 vs. 1.44 ± 0.57, respectively; P < 0.001).

CONCLUSION

These results support the hypothesis that stress shielding is a contributor to vertebral body bone loss and may increase fracture risk. Although further studies are needed, there may be a role for interventions that can shift vertebral loading in the spine to help prevent fracture.

Reference ranges for vertebral heights and prevalence of asymptomatic (undiagnosed) vertebral fracture in Vietnamese men and women

Based on quantitative measurements of vertebral heights, the prevalence of undiagnosed vertebral fracture in Vietnamese men and women aged 50 years and older was 23 and 26 %, respectively.

BACKGROUND

The present study sought to develop reference ranges for vertebral heights and to determine the prevalence of asymptomatic vertebral fracture in Vietnamese men and women.

METHODS

The study included 312 men and 657 women aged over 18 who were randomly selected from the community. The ImageJ software program was used to measure anterior height (H(a)), middle height (H(m)), and posterior height (H(p)) for each vertebra (T4 to T12 and L1 to L5). Four vertebral ratios were determined: H(a)/H(p), H(m)/H(p), H(p)/H(p + 1), and H(p)/H(p − 1). Reference ranges for the ratios were then developed by the method of Winsorized mean. Vertebral fracture was diagnosed as a ratio lower than three standard deviations from the normal mean.

RESULTS

For any given vertebra, H(a), H(m), and H(p) in men were higher than in women. In both sexes, H(a) and H(m) increased in a stepwise fashion from T4 to L3 and then gradually reduced in L4–L5. Vertebral heights for T4–T9 tended to decrease, while vertebral height for T10–L5 tended to increase with advancing age. Among those aged over 50 years, the prevalence of vertebral fracture in men was 23.3 % (95 % confidence interval (CI) 16.8–31.3 %) which was lower than that in women (26.5 %; 95 % CI 22.4–31.1 %). The prevalence increased with advancing age, such that from the age of over 70, 41 % of men and 42 % women had at least one vertebral fracture.

CONCLUSION

One fourth of Vietnamese men and women aged 50 years and older have a symptomatic vertebral fracture. This prevalence is equivalent to that in Caucasian populations.

The effect of 3 versus 6 years of zoledronic acid treatment of osteoporosis: a randomized extension to the HORIZON-Pivotal Fracture Trial (PFT)

Zoledronic acid 5 mg (ZOL) annually for 3 years reduces fracture risk in postmenopausal women with osteoporosis. To investigate long-term effects of ZOL on bone mineral density (BMD) and fracture risk, the Health Outcomes and Reduced Incidence with Zoledronic acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT) was extended to 6 years. In this international, multicenter, double-blind, placebo-controlled extension trial, 1233 postmenopausal women who received ZOL for 3 years in the core study were randomized to 3 additional years of ZOL (Z6, n = 616) or placebo (Z3P3, n = 617). The primary endpoint was femoral neck (FN) BMD percentage change from year 3 to 6 in the intent-to-treat (ITT) population. Secondary endpoints included other BMD sites, fractures, biochemical bone turnover markers, and safety. In years 3 to 6, FN-BMD remained constant in Z6 and dropped slightly in Z3P3 (between-treatment difference = 1.04%; 95% confidence interval 0.4 to 1.7; p = 0.0009) but remained above pretreatment levels. Other BMD sites showed similar differences. Biochemical markers remained constant in Z6 but rose slightly in Z3P3, remaining well below pretreatment levels in both. New morphometric vertebral fractures were lower in the Z6 (n = 14) versus Z3P3 (n = 30) group (odds ratio = 0.51; p = 0.035), whereas other fractures were not different. Significantly more Z6 patients had a transient increase in serum creatinine >0.5 mg/dL (0.65% versus 2.94% in Z3P3). Nonsignificant increases in Z6 of atrial fibrillation serious adverse events (2.0% versus 1.1% in Z3P3; p = 0.26) and stroke (3.1% versus 1.5% in Z3P3; p = 0.06) were seen. Postdose symptoms were similar in both groups. Reports of hypertension were significantly lower in Z6 versus Z3P3 (7.8% versus 15.1%, p < 0.001). Small differences in bone density and markers in those who continued versus those who stopped treatment suggest residual effects, and therefore, after 3 years of annual ZOL, many patients may discontinue therapy up to 3 years. However, vertebral fracture reductions suggest that those at high fracture risk, particularly vertebral fracture, may benefit by continued treatment.

Prevalence of vertebral fractures in women and men in the population-based Tromsø Study

Background

Osteoporotic vertebral fractures are, as the hip fractures, associated with increased morbidity and mortality. Norway has one of the highest reported incidences of hip fractures in the world. Because of methodological challenges, vertebral fractures are not extensively studied. The aim of this population based study was to describe, for the first time, the age- and sex specific occurrence of osteoporotic vertebral fractures in Norway.

Methods

Data was collected in the Tromso Study, 2007/8 survey. By the use of dual x-ray absorptiometry (GE Lunar Prodigy) vertebral fracture assessments were performed in 2887 women and men aged from 38 to 87 years, in addition to measurements of bone mineral density at the femoral sites. Information on lifestyle was collected through questionnaires. Comparisons between fractures and non-fractures were done sex stratified, by univariate analyses, adjusting for age when relevant.

Results

The prevalence of vertebral fractures varied from about 3% in the age group below 60 to about 19% in the 70+ group in women, and from 7.5% to about 20% in men, with an overall prevalence of 11.8% in women and 13.8% in men (p = 0.07). Among those with fractures, only one fracture was the most common; two and more fractures were present in approximately 30% of the cases. Fractures were seen from the fourth lumbar to the fifth thoracic vertebrae, most common between first lumbar and sixth thoracic vertebrae. The most common type of fracture was the wedge type in both sexes. Bone mineral density at the hip differed significantly according to type of fracture, being highest in those with wedge fractures and lowest in those with compression fractures.

Conclusions

The prevalence of vertebral fractures increased by age in women and men, but the overall prevalence was lower than expected, considering the high prevalence of hip and forearm fractures in Norway. In both sexes, the wedge type was the fracture type most frequently observed and most common in the thoracic region.

Recognition of morphometric vertebral fractures by artificial neural networks: analysis from GISMO Lombardia Database

BACKGROUND

It is known that bone mineral density (BMD) predicts the fracture's risk only partially and the severity and number of vertebral fractures are predictive of subsequent osteoporotic fractures (OF). Spinal deformity index (SDI) integrates the severity and number of morphometric vertebral fractures. Nowadays, there is interest in developing algorithms that use traditional statistics for predicting OF. Some studies suggest their poor sensitivity. Artificial Neural Networks (ANNs) could represent an alternative. So far, no study investigated ANNs ability in predicting OF and SDI. The aim of the present study is to compare ANNs and Logistic Regression (LR) in recognising, on the basis of osteoporotic risk-factors and other clinical information, patients with SDI≥1 and SDI≥5 from those with SDI = 0.

METHODOLOGY

We compared ANNs prognostic performance with that of LR in identifying SDI≥1/SDI≥5 in 372 women with postmenopausal-osteoporosis (SDI≥1, n = 176; SDI = 0, n = 196; SDI≥5, n = 51), using 45 variables (44 clinical parameters plus BMD). ANNs were allowed to choose relevant input data automatically (TWIST-system-Semeion). Among 45 variables, 17 and 25 were selected by TWIST-system-Semeion, in SDI≥1 vs SDI = 0 (first) and SDI≥5 vs SDI = 0 (second) analysis. In the first analysis sensitivity of LR and ANNs was 35.8% and 72.5%, specificity 76.5% and 78.5% and accuracy 56.2% and 75.5%, respectively. In the second analysis, sensitivity of LR and ANNs was 37.3% and 74.8%, specificity 90.3% and 87.8%, and accuracy 63.8% and 81.3%, respectively.

CONCLUSIONS

ANNs showed a better performance in identifying both SDI≥1 and SDI≥5, with a higher sensitivity, suggesting its promising role in the development of algorithm for predicting OF.

Relation of vertebral deformities to bone density, structure, and strength

Because they are not reliably discriminated by areal bone mineral density (aBMD) measurements, it is unclear whether minimal vertebral deformities represent early osteoporotic fractures. To address this, we compared 90 postmenopausal women with no deformity (controls) with 142 women with one or more semiquantitative grade 1 (mild) deformities and 51 women with any grade 2-3 (moderate/severe) deformities. aBMD was measured by dual-energy X-ray absorptiometry (DXA), lumbar spine volumetric bone mineral density (vBMD) and geometry by quantitative computed tomography (QCT), bone microstructure by high-resolution peripheral QCT at the radius (HRpQCT), and vertebral compressive strength and load-to-strength ratio by finite-element analysis (FEA) of lumbar spine QCT images. Compared with controls, women with grade 1 deformities had significantly worse values for many bone density, structure, and strength parameters, although deficits all were much worse for the women with grade 2-3 deformities. Likewise, these skeletal parameters were more strongly associated with moderate to severe than with mild deformities by age-adjusted logistic regression. Nonetheless, grade 1 vertebral deformities were significantly associated with four of the five main variable categories assessed: bone density (lumbar spine vBMD), bone geometry (vertebral apparent cortical thickness), bone strength (overall vertebral compressive strength by FEA), and load-to-strength ratio (45-degree forward bending ÷ vertebral compressive strength). Thus significantly impaired bone density, structure, and strength compared with controls indicate that many grade 1 deformities do represent early osteoporotic fractures, with corresponding implications for clinical decision making.

Reference values for vertebral shape in young Chinese women: implication for assessment of vertebral deformity

The race- and sex-specific reference values for vertebral shape are important to determine the prevalence of osteoporotic vertebral fracture. However, these reference values are absent in Chinese women. In the present study, the anterior, middle and posterior heights and the ratios of these heights were measured from 14 vertebral bodies (T4-L5) in 60 premenopausal Chinese women (aged 19-25 years). Cutoff values were set as standard deviations (3 and 3.5 SD) and percentages (15 and 20%) below the means of vertebral height (VH) ratios to define vertebral deformities. The number of subjects with a VH ratio lower than -15% cutoff were significantly more than those with a VH ratio lower than -3 SD cutoff (p < 0.05), but this difference did not occur when a -20% cutoff was selected. A few VH ratios were distributed below -20% and -3 SD cutoffs, and none was below -3.5 SD. The vertebral shape defined by VH ratios was different between Chinese and European women. We conclude that 3.5 SD below the reference mean is an ideal cutoff value for the definition of prevalent vertebral fractures in Chinese women, and reference data should be obtained from young premenopausal women.

Spinal deformity index (SDI) is a good predictor of incident vertebral fractures

The spinal deformity index is a convenient tool to quantify the number and the severity of prevalent vertebral fractures. It is a predictor of the risk of sustaining incident vertebral fracture. This quantification must be taken into account to improve management of patients.

INTRODUCTION

Prevalent fractures are strong risk factors for subsequent fractures.

METHODS

The study subjects were women from the placebo groups of two studies of strontium ranelate in postmenopausal osteoporosis (N = 723 and 637 patients, respectively). Three lateral radiographs of the spine were obtained at baseline and annually over 3 years, according to standardized procedures. The semiquantitative visual assessment of each vertebra from T4 to L4 was performed by the same reader throughout the study. A spinal deformity index (SDI) was calculated by summing for each patient the grade of each vertebra from T4 to L4.

RESULTS

There was a linear relationship between baseline SDI and the 3-year incidence of vertebral fracture (adjusted R(2) = 0.76). The 3-year incidence of vertebral fractures was different among the tertiles of baseline SDI: 17.3 +/- 3.6%, 25.4 +/- 2.6%, and 47.6 +/- 3.1% from the lowest to the highest, respectively. There was no relationship between SDI and non-vertebral fractures incidence.

CONCLUSION

SDI is a good predictor of incident vertebral fractures. Patients with highest SDI should receive highest priority to treatment.

Trend in incidence of osteoporosis-related fractures among 40- to 69-year-old women: analysis of a large insurance claims database, 2000-2005

OBJECTIVE

To determine the trend in incidence of fractures among perimenopausal and postmenopausal women during the periods immediately before and after publication of the Women's Health Initiative and Heart and Estrogen/Progestin Replacement Study (HERS) II data.

DESIGN

This was an ecological study using a claims database for multiple healthcare plans. The cohort of women aged 40 to 69 years was included. Diagnostic codes for fractures likely to be osteoporosis related and prescriptions for hormone therapy and other bone-modifying medications were identified. Annual incidence rates and trends in incidence over time for fractures and prescriptions were determined for the period 2000 through 2005.

RESULTS

Enrollment among women aged 40 to 69 years increased from 919,389 in 2000 to 2,872,372 in 2005. A total of 43,017 new fractures were identified. There was a significant increasing trend in age-adjusted rates of radius and ulna, vertebra, ribs, hip, pelvis, multiple, and pathologic fractures during the period from 2003 through 2005 (P < 0.03). The incidence of each fracture type was significantly greater during 2004 to 2005 than 2000 to 2001 (P < 0.04). The use of estrogen, estrogen plus progestin, and other hormones declined over the period from 2000 to 2003, whereas the use of other bone-modifying drugs increased from 2003 through 2005.

CONCLUSIONS

The incidence of fractures among perimenopausal and postmenopausal women increased significantly in the 3 years after publication of Women's Health Initiative and Heart and Estrogen/Progestin Replacement Study II results. This trend followed a decline in the use of hormone therapy, concurrent with an increase in the use of other bone-modifying agents.

Fracture risk in type 2 diabetes: update of a population-based study

We found no significant excess of fractures among Rochester, MN, residents with diabetes mellitus initially recognized in 1950-1969, but more recent studies elsewhere have documented an apparent increase in hip fracture risk. To explore potential explanations for any increase in fractures, we performed an historical cohort study among 1964 Rochester residents who first met glycemic criteria for diabetes in 1970-1994 (mean age, 61.7 +/-14.0 yr; 51% men). Fracture risk was estimated by standardized incidence ratios (SIRs), and risk factors were evaluated in Andersen-Gill time-to-fracture regression models. In 23,236 person-years of follow-up, 700 diabetic residents experienced 1369 fractures documented by medical record review. Overall fracture risk was elevated (SIR, 1.3; 95% CI, 1.2-1.4), but hip fractures were increased only in follow-up beyond 10 yr (SIR, 1.5; 95% CI, 1.1-1.9). As expected, fracture risk factors included age, prior fracture, secondary osteoporosis, and corticosteroid use, whereas higher physical activity and body mass index were protective. Additionally, fractures were increased among patients with neuropathy (hazard ratio [HR], 1.3; 95% CI, 1.1-1.6) and those on insulin (HR, 1.3; 95% CI, 1.1-1.5); risk was reduced among users of biquanides (HR, 0.7; 95% CI, 0.6-0.96), and no significant influence on fracture risk was seen with sulfonylurea or thiazolidinedione use. Thus, contrary to our earlier study, the risk of fractures overall (and hip fractures specifically) was increased among Rochester residents with diabetes, but there was no evidence that the rise was caused by greater levels of obesity or newer treatments for diabetes.

Mild prevalent and incident vertebral fractures are risk factors for new fractures

This prospective four-year study indicates that post-menopausal osteoporotic women with mild prevalent and incident vertebral fractures have an increased risk of incident fractures.

INTRODUCTION

Mild vertebral fractures are under diagnosed as there is disagreement about their clinical significance. Our aim was to assess the risk of subsequent fractures induced by both prevalent and incident mild vertebral fractures in osteoporotic post-menopausal women.

PATIENTS AND METHODS

Three thousand three hundred and fifty-eight patients, aged 74 +/- 6 years, with post-menopausal osteoporosis included in the placebo groups of two clinical trials of strontium ranelate were followed for 4 years. A Cox regression model adjusted on age, body mass index and bone mineral density was used to calculate the relative risk (RR) of fracture in subjects with only mild fractures as compared to patients without fracture, and to patients with at least one grade >or= 2 fracture. These calculations were made for prevalent and then incident fractures.

RESULTS

The RR of vertebral fracture in 4 years was 1.8 (1.3-2.4) p < 0.001, and 2.7 (2.3-3.3) p < 0.001 for patients having only mild vertebral fractures and at least one grade >or= 2 fracture at baseline respectively. The RR of vertebral fracture in the 3rd and 4th years of follow-up was 1.7 (1.1-2.6) p = 0.01, and 1.9 (1.3-2.6) p < 0.001 for patients having during the first 2 years incident mild fractures only, and for patients having at least one grade >or= 2 incident fracture respectively. The RR of non-vertebral fracture in 4 years was 1.3 (0.9-1.9) p = 0.15 and 1.7 (1.4-2.1) p < 0.001 for patients having only mild or at least one grade >or= 2 vertebral fracture at baseline respectively. For patients aged more than 70 years, these RR were 1.45 (0.99-2.11) (p = 0.06), and 1.72 (1.36-2.18) p < 0.001 respectively. The RR of non-vertebral fracture in the 3rd and 4th years was 1.68 (1.36-2.09) p < 0.001 for patients having at least one grade >or= 2 incident fracture during the 2 first years of follow-up.

CONCLUSION

Mild vertebral fractures are a risk factor for subsequent vertebral and non-vertebral fracture in postmenopausal women with osteoporosis; 1 out of 4 patients with an incident mild vertebral fracture in 2 years will fracture again within the 2 next years.

Structural determinants of vertebral fracture risk

Vertebral fractures are more strongly associated with specific bone density, structure, and strength parameters than with areal BMD, but all of these variables are correlated.

INTRODUCTION

It is unclear whether the association of areal BMD (aBMD) with vertebral fracture risk depends on bone density per se, bone macro- or microstructure, overall bone strength, or spine load/bone strength ratios.

MATERIALS AND METHODS

From an age-stratified sample of Rochester, MN, women, we identified 40 with a clinically diagnosed vertebral fracture (confirmed semiquantitatively) caused by moderate trauma (cases; mean age, 78.6 +/- 9.0 yr) and compared them with 40 controls with no osteoporotic fracture (mean age, 70.9 +/- 6.8 yr). Lumbar spine volumetric BMD (vBMD) and geometry were assessed by central QCT, whereas microstructure was evaluated by high-resolution pQCT at the ultradistal radius. Vertebral failure load ( approximately strength) was estimated from voxel-based finite element models, and the factor-of-risk (phi) was determined as the ratio of applied spine loads to failure load.

RESULTS

Spine loading (axial compressive force on L3) was similar in vertebral fracture cases and controls (e.g., for 90 degrees forward flexion, 2639 versus 2706 N; age-adjusted p = 0.173). However, fracture cases had inferior values for most bone density and structure variables. Bone strength measures were also reduced, and the factor-of-risk (phi) was 35-37% greater (worse) among women with a vertebral fracture. By age-adjusted logistic regression, relative risks for the strongest fracture predictor in each of the five main variable categories were bone density (total lumbar spine vBMD: OR per SD change, 2.2; 95% CI, 1.1-4.3), bone geometry (vertebral apparent cortical thickness: OR, 2.1; 95% CI, 1.1-4.1), bone microstructure (none significant); bone strength ("cortical" [outer 2 mm] compressive strength: OR, 2.5; 95% CI, 1.3-4.8), and factor-of-risk (phi for 90 degrees forward flexion/overall vertebral compressive strength: OR, 3.2; 95% CI, 1.4-7.5). These variables were correlated with spine aBMD (partial r, -0.32 to 0.75), but each was a stronger predictor of fracture in the logistic regression analyses.

CONCLUSIONS

The association of aBMD with vertebral fracture risk is explained by its correlation with more specific bone density, structure, and strength parameters. These may allow deeper insights into fracture pathogenesis.

Standardised quantitative morphometry: a modified approach for quantitative identification of prevalent vertebral deformities

Our approach for the quantitative identification of vertebral deformity (standardised quantitative morphometry, SQM) reduces problems associated with obtaining reference intervals from populations with high prevalence of fracture. In women with osteoporosis, agreement with radiological diagnosis (surrogate gold standard) was better for SQM than QM using the Eastell-Melton method.

INTRODUCTION

Use of reference intervals for quantitative vertebral morphometry (QM) derived by statistical trimming can be problematic in reference populations with high prevalence of deformity. We have developed a modified approach known as standardised quantitative morphometry (SQM), whereby vertebral height is standardised to eliminate variation between individuals. The aims of this study were to compare SQM to QM (Eastell-Melton method) for identification of prevalent vertebral deformities, using qualitative radiological diagnosis as the gold standard, and automate the process.

METHODS

Our study populations were a clinic-based sample of 80 women ages 48 to 87 years with a high prevalence of vertebral deformity and a general practice (GP)-based sample of 372 women ages 50 to 85 years. Agreement with the gold standard was tested for SQM and QM.

RESULTS

Agreement was better for SQM (kappa = 0.80) than for QM (kappa = 0.14) in the clinic sample using clinic-based reference data. The agreement was improved for QM using the GP-based reference data, kappa = 0.63. In the GP population, agreement was good for both SQM and QM (kappa = 0.59 and 0.54 respectively).

CONCLUSIONS

In our population with a high prevalence of vertebral fracture, SQM performs better than the Eastell-Melton method.

Age- and sex-specific differences in the factor of risk for vertebral fracture: a population-based study using QCT

We used QCT scans obtained in 687 men and women, 21-97 years of age, to estimate the factor of risk for vertebral fracture, Phi(vert), defined as the ratio of spinal loading to vertebral strength. With age, vertebral strength declined and Phi(vert) increased significantly more in women than men. Age- and sex-specific differences in Phi(vert) closely resembled previously reported vertebral fracture incidence.

INTRODUCTION

Despite the high prevalence of vertebral fractures, little is known about the interaction between spinal loading and vertebral fragility.

MATERIALS AND METHODS

We assessed the ratio of spinal loading to vertebral strength (i.e., the factor of risk, Phi(vert)) in an age- and sex-stratified population-based sample of 700 women and men 21-97 years of age. We measured volumetric BMD (vBMD, mg/cm3) and cross-sectional area (CSA, cm2) of the midvertebral bodies of L1-L3 using QCT and computed vertebral compressive strength from these data using engineering beam theory. A biomechanical model of the trunk was used to estimate compressive forces applied to the L3 vertebral body during standing, bending forward, and bending forward while lifting 10 kg. The factor of risk for fracture, Phi(vert), was computed as the ratio of spinal compressive force to vertebral strength for each activity.

RESULTS

Men had a higher vertebral strength at all ages, largely because of their greater CSA. Whereas both sexes exhibited a marked decline in vertebral compressive strength with age (p < 0.001), the decline was greater in women than men (-43% versus -31%, p = 0.008). Compressive forces on L3 were greater in men than women, because of their greater body weight and height. For both sexes, forces during bending and lifting were 8-fold higher than those experienced during upright standing. For all activities, Phi(vert) increased with age, but significantly more so in women than men (p < 0.001). For bending and lifting, Phi(vert-bending) exceeded 1.0 in 30% of women and 12% of men > or =50 years of age, values that are similar to the reported frequency of vertebral fracture.

CONCLUSION

These findings illustrate potential mechanisms underlying vertebral fractures and provide strong rationale for further evaluation of this QCT-based biomechanical approach for assessment of fracture risk.