Bone mineral density testing in healthy postmenopausal women. The role of clinical risk factor assessment in determining fracture risk

Application of the World Health Organization Fracture Risk Assessment Tool to predict need for dual-energy X-ray absorptiometry scanning in postmenopausal women

OBJECTIVE

To evaluate the efficacy of the World Health Organization Fracture Risk Assessment Tool, excluding bone mineral density (pre-BMD FRAX), in identifying Taiwanese postmenopausal women needing dual-energy X-ray absorptiometry (DXA) examination for further treatment.

MATERIALS AND METHODS

The pre-BMD FRAX score was calculated for 231 postmenopausal women who participated in public health education workshops in the local Keelung community, Taiwan. DXA scanning and vertebral fracture assessment (VFA) were arranged for women classified as intermediate or high risk for fracture using the pre-BMD FRAX fracture probability.

RESULTS

Pre-BMD FRAX classified 26 women as intermediate risk and 37 as having high risk for fracture. Subsequent DXA scans for these 63 women showed that 36 were osteoporotic, 19 were osteopenic, and eight had normal bone density. Concurrent VFA revealed 25 spine factures in which 14 were osteoporotic, seven were osteopenic, and four had normal bone density. The efficacy of the pre-BMD FRAX score to identify those patients with low bone mass by DXA was 87.3% (55/63). When VFA was combined with BMD to identify those patients with high risk (osteopenia, osteoporosis, or spinal fracture), the efficacy of the pre-BMD score increased to 93.7% (59/63). According to the National Osteoporosis Foundation, the overall concordance between pre-BMD FRAX and BMD, expressed through the kappa index, was 0.967. Compared with the evaluation when BMD was used alone, there was a significant increase in efficacy in identifying women who need treatment using BMD plus VFA or FRAX plus BMD. Furthermore, the highest efficacy was achieved when FRAX with BMD and VFA was used.

CONCLUSION

The pre-BMD FRAX score not only efficiently predicts postmenopausal patients who are potentially at risk and might require treatment but also reduces unnecessary DXA use. Concurrent VFA during DXA use increases spine fracture detection. This improvement in diagnostic efficacy allows clinicians to provide the most appropriate therapeutic recommendation.

Relationship of calf circumference with bone mineral density and hip geometry: a hospital-based cross-sectional study

Calf circumference has significant predictive value for bone mineral density (BMD) at hip and spine and for fracture at spine in both genders and hence may be used as a clinical risk factor for fracture when BMD is not available.

INTRODUCTION

Lean muscle mass and higher regular physical ability has been shown to correlate with BMD and hip geometry. Calf circumference is an indicator of muscle mass. We examined the association of calf circumference (CC), thigh circumference (TC), and physical performances with BMD and hip geometry.

MATERIALS AND METHODS

Females above 45 years (at least 5 years postmenopausal) and males above 55 years were enrolled. Bilateral CC and TC were measured, and BMD was assessed at neck of femur (NF), trochanter (TR), inter-trochanter (IT), spine, and forearm. Dual energy X-ray absorptiometry scan-based hip geometry parameters were analyzed.

RESULTS

One hundred sixteen subjects (29 males and 87 females) were enrolled. CC correlated significantly with BMD at NF, IT, TR, and spine in male and female, respectively, and at forearm in female. Multivariate regression analysis showed CC as a significant predictor of BMD (at TR, IT, NF, and spine in both genders) and fracture (at spine in both genders). CC had significant positive correlation with hip parameters-cross-sectional area; cortical thickness; and section modulus at NF, IT, and TR in both genders and negative correlation with buckling ratio at NF and IT in females.

CONCLUSION

CC is a significant predictor of BMD at hip and spine and fracture at spine in both genders.

Assessment of the 10-year risk of fracture in Italian postmenopausal women using FRAX®: a north Italian multicenter study

The aim of the study was to estimate the absolute risk of fracture in a sample of postmenopausal women with the Italian version of FRAX®, using femoral neck bone mineral density (BMD) and 3 internationally validated clinical risk factors (CRFs) (history of fragility fracture, family history of hip fracture, current smoking). We retrospectively studied 9586 women (mean age 64.1 yr) examined in three osteoporosis centers from Northern Italy over two years (2001-2002). The risk of major osteoporotic (clinical spine, hip, forearm and humerus) and hip fractures was estimated using the online version of the FRAX algorithm adapted for Italy. The median 10-year risk was 7.5% for osteoporotic fracture and 1.7% for hip fracture. 25% of subjects had a 10-year risk ≥ 12.1% for osteoporotic fracture and ≥ 4.1% for hip fracture. The median 10-year risk of fracture increased with the number of prevalent CRFs. For major osteoporotic fractures risk rose from 6.3% to 10.9%, 21.4% and 40.9% with 1, 2 and 3 prevalent CRFs, respectively. For hip fractures the corresponding figures were: 1.3%, 2.7%, 7.0% and 21.9%, respectively. However, it must be emphasized that in 2 out of 3 women, none of the CRFs examined was present and the assessment of risk was limited to age and BMD. Our data provide the first description of the effect of the combination of BMD, age and CRFs on fracture risk stratification in a large sample of Italian postmenopausal women using FRAX®. The results are a useful starting point to define criteria for the application of FRAX® in clinical practice in Italy.

A FRAX® model for the assessment of fracture probability in Belgium

A country-specific FRAX® model was developed from the epidemiology of fracture and death in Belgium. Fracture probabilities were identified that corresponded to currently accepted reimbursement thresholds.

INTRODUCTION

The objective of this study was to evaluate a Belgian version of the WHO fracture risk assessment (FRAX®) tool to compute 10-year probabilities of osteoporotic fracture in men and women. A particular aim was to determine fracture probabilities that corresponded to the reimbursement policy for the management of osteoporosis in Belgium and the clinical scenarios that gave equivalent fracture probabilities.

METHODS

Fracture probabilities were computed from published data on the fracture and death hazards in Belgium. Probabilities took account of age, sex, the presence of clinical risk factors and femoral neck bone mineral density (BMD). Fracture probabilities were determined that were equivalent to intervention (reimbursement) thresholds currently used in Belgium.

RESULTS

Fracture probability increased with age, lower BMI, decreasing BMD T-score and all clinical risk factors used alone or combined. The 10-year probabilities of a major osteoporosis-related fracture that corresponded to current reimbursement guidelines ranged from approximately 7.5% at the age of 50 years to 26% at the age of 80 years where a prior fragility fracture was used as an intervention threshold. For women at the threshold of osteoporosis (femoral neck T-score = -2.5 SD), the respective probabilities ranged from 7.4% to 15%. Several combinations of risk-factor profiles were identified that gave similar or higher fracture probabilities than those currently accepted for reimbursement in Belgium.

CONCLUSIONS

The FRAX® tool has been used to identify possible thresholds for therapeutic intervention in Belgium, based on equivalence of risk with current guidelines. The FRAX® model supports a shift from the current DXA-based intervention strategy, towards a strategy based on fracture probability of a major osteoporotic fracture that in turn may improve identification of patients at increased fracture risk. The approach will need to be supported by health economic analyses.

OSTEOPOROSIS DIAGNOSIS AND TREATMENT

Articles that update the state of knowledge regarding osteoporosis run the risk of quickly becoming obsolete because research and studies on osteoporosis today are arousing great interest among researchers, the pharmaceutical and medical equipment industries, governments and even WHO. All orthopedists know about osteoporosis because of its most deleterious effect: osteoporotic fracture. Osteoporosis without fractures does not arouse suspicion because this is a pathological condition with a nonspecific clinical profile. Osteoporotic fractures have an economic cost (from treatment), a social cost (from its sequelae) and a medical cost (from deaths). Many fractures could be avoided through diagnosing osteoporosis prior to the first fracture and thus many temporary and permanent disabilities could be avoided and many lives saved. Awareness of the risk factors for osteoporosis raises suspicions and bone densitometry aids in diagnosis. Treatment should be based on the physiopathology of the disease. Hence, for prevention or treatment of osteoporosis, the activity of osteoclasts should be diminished or the activity of osteoblasts should be increased, or both. Treatment that reduces the incidence of fractures by improving the bone geometry and microarchitecture would be ideal. Newly formed bone tissue needs to have good cell and matrix quality, normal mineralization, a good ratio between mineralized (mechanically resistant) and non-mineralized (flexible) bone, and no accumulated damage. The ideal treatment should have a positive remodeling rate and fast and long-lasting therapeutic effects. Such effects need to be easily detectable. They need to be safe.

Ten-year fracture probability identifies women who will benefit from clodronate therapy--additional results from a double-blind, placebo-controlled randomised study

Fracture risk prediction can be enhanced by the concurrent assessment of other clinical risk factors. This study demonstrates that the estimation of an individual's 10-year probability of fracture by the FRAX algorithm identifies patients at high risk of fracture who will respond to bisphosphonate therapy.

INTRODUCTION

Treatments for osteoporosis are targeted largely to patients with low bone density (BMD) or a prior fragility fracture. Fracture risk prediction can be enhanced by the concurrent assessment of other clinical risk factors, but it is important to determine whether the risk so identified can be reduced by intervention. We determined the effect of a bisphosphonate on fracture rates when risk was calculated using a new risk algorithm (FRAX).

METHODS

Women aged 75 years or more were recruited to a randomised, double-blind controlled trial of 800 mg oral clodronate (Bonefos) daily over 3 years. Baseline clinical risk factors were entered in the FRAX model to compute the 10-year probability of major osteoporotic fractures with or without input of femoral neck BMD. The interaction between fracture probability and treatment efficacy was examined by Poisson regression.

RESULTS

In 3,974 women, the interaction between fracture probability and treatment efficacy was significant when probability was assessed without BMD (p = 0.043), but not when BMD was included (p = 0.10). Efficacy was more evident in those deemed at highest risk. For example women lying at the 75th percentile of fracture probability in the absence of BMD (10-year probability 24%) treatment reduced fracture risk by 27% (HR 0.73, 95%CI 0.58-0.92). In those with a fracture probability of 30% (90th percentile), the fracture risk reduction was 38% (HR 0.62, 0.46-0.84).

CONCLUSIONS

The estimation of an individual's 10-year probability of fracture by the FRAX algorithm identifies patients at high risk of fracture who will respond to bisphosphonate therapy.

Assessment of the 10-year probability of osteoporotic hip fracture combining clinical risk factors and heel bone ultrasound: the EPISEM prospective cohort of 12,958 elderly women

This study aimed to develop a hip screening tool that combines relevant clinical risk factors (CRFs) and quantitative ultrasound (QUS) at the heel to determine the 10-yr probability of hip fractures in elderly women. The EPISEM database, comprised of approximately 13,000 women 70 yr of age, was derived from two population-based white European cohorts in France and Switzerland. All women had baseline data on CRFs and a baseline measurement of the stiffness index (SI) derived from QUS at the heel. Women were followed prospectively to identify incident fractures. Multivariate analysis was performed to determine the CRFs that contributed significantly to hip fracture risk, and these were used to generate a CRF score. Gradients of risk (GR; RR/SD change) and areas under receiver operating characteristic curves (AUC) were calculated for the CRF score, SI, and a score combining both. The 10-yr probability of hip fracture was computed for the combined model. Three hundred seven hip fractures were observed over a mean follow-up of 3.2 yr. In addition to SI, significant CRFs for hip fracture were body mass index (BMI), history of fracture, an impaired chair test, history of a recent fall, current cigarette smoking, and diabetes mellitus. The average GR for hip fracture was 2.10 per SD with the combined SI + CRF score compared with a GR of 1.77 with SI alone and of 1.52 with the CRF score alone. Thus, the use of CRFs enhanced the predictive value of SI alone. For example, in a woman 80 yr of age, the presence of two to four CRFs increased the probability of hip fracture from 16.9% to 26.6% and from 52.6% to 70.5% for SI Z-scores of +2 and -3, respectively. The combined use of CRFs and QUS SI is a promising tool to assess hip fracture probability in elderly women, especially when access to DXA is limited.

FRAX and the assessment of fracture probability in men and women from the UK

A fracture risk assessment tool (FRAX) is developed based on the use of clinical risk factors with or without bone mineral density tests applied to the UK.

INTRODUCTION

The aim of this study was to apply an assessment tool for the prediction of fracture in men and women with the use of clinical risk factors (CRFs) for fracture with and without the use of femoral neck bone mineral density (BMD). The clinical risk factors, identified from previous meta-analyses, comprised body mass index (BMI, as a continuous variable), a prior history of fracture, a parental history of hip fracture, use of oral glucocorticoids, rheumatoid arthritis and other secondary causes of osteoporosis, current smoking, and alcohol intake 3 or more units daily.

METHODS

Four models were constructed to compute fracture probabilities based on the epidemiology of fracture in the UK. The models comprised the ten-year probability of hip fracture, with and without femoral neck BMD, and the ten-year probability of a major osteoporotic fracture, with and without BMD. For each model fracture and death hazards were computed as continuous functions.

RESULTS

Each clinical risk factor contributed to fracture probability. In the absence of BMD, hip fracture probability in women with a fixed BMI (25 kg/m(2)) ranged from 0.2% at the age of 50 years for women without CRF's to 22% at the age of 80 years with a parental history of hip fracture (approximately 100-fold range). In men, the probabilities were lower, as was the range (0.1 to 11% in the examples above). For a major osteoporotic fracture the probabilities ranged from 3.5% to 31% in women, and from 2.8% to 15% in men in the example above. The presence of one or more risk factors increased probabilities in an incremental manner. The differences in probabilities between men and women were comparable at any given T-score and age, except in the elderly where probabilities were higher in women than in men due to the higher mortality of the latter.

CONCLUSION

The models provide a framework which enhances the assessment of fracture risk in both men and women by the integration of clinical risk factors alone and/or in combination with BMD.

Absolute fracture risk reporting in clinical practice: a physician-centered survey

Non-expert clinical practitioners who had received bone density reports based on 10-year absolute fracture risk were surveyed to determine their response to this new system. Absolute fracture risk reporting was well received and was strongly preferred to traditional T-score-based reporting. Non-specialist physicians were particularly supportive of risk-based bone mineral density (BMD) reporting.

INTRODUCTION

Absolute risk estimation is preferable to risk categorization based upon BMD alone. The objective of this study was to specifically assess the response of non-expert clinical practitioners to this approach.

METHODS

In January 2006, the Province of Manitoba, Canada, started reporting 10-year osteoporotic fracture risks for patients aged 50 years and older based on the hip T-score, gender, age, and multiple clinical risk factors. In May 2006 and October 2006, a brief anonymous survey was sent to all physicians who had requested a BMD test during 2005 and 206 responses were received.

RESULTS

When asked whether the report contained the information needed to manage patients, the mean score for the absolute fracture risk report was higher than for the T-score-based report (p<0.0001). When asked whether the report was easy to understand, the mean score for the absolute fracture risk report was again higher than for the T-score-based report (p<0.0001). Non-specialists gave a higher ranking than specialists to the absolute fracture risk information (p<0.05).

CONCLUSIONS

Absolute fracture risk reporting is well-received by physicians and is strongly preferred to traditional T-score-based reporting. Non-specialist physicians are particularly supportive of risk-based BMD reporting.

Combining clinical factors and quantitative ultrasound improves the detection of women both at low and high risk for hip fracture

We hypothesized that combining clinical risk factors (CRF) with the heel stiffness index (SI) measured via quantitative ultrasound (QUS) would improve the detection of women both at low and high risk for hip fracture. Categorizing women by risk score improved the specificity of detection to 42.4%, versus 33.8% using CRF alone and 38.4% using the SI alone. This combined CRF-SI score could be used wherever and whenever DXA is not readily accessible.

INTRODUCTION AND HYPOTHESIS

Several strategies have been proposed to identify women at high risk for osteoporosis-related fractures; we wanted to investigate whether combining clinical risk factors (CRF) and heel QUS parameters could provide a more accurate tool to identify women at both low and high risk for hip fracture than either CRF or QUS alone.

METHODS

We pooled two Caucasian cohorts, EPIDOS and SEMOF, into a large database named "EPISEM", in which 12,064 women, 70 to 100 years old, were analyzed. Amongst all the CRF available in EPISEM, we used only the ones which were statistically significant in a Cox multivariate model. Then, we constructed a risk score, by combining the QUS-derived heel stiffness index (SI) and the following seven CRF: patient age, body mass index (BMI), fracture history, fall history, diabetes history, chair-test results, and past estrogen treatment.

RESULTS

Using the composite SI-CRF score, 42% of the women who did not report a hip fracture were found to be at low risk at baseline, and 57% of those who subsequently sustained a fracture were at high risk. Using the SI alone, corresponding percentages were 38% and 52%; using CRF alone, 34% and 53%. The number of subjects in the intermediate group was reduced from 5,400 (including 112 hip fractures) and 5,032 (including 111 hip fractures) to 4,549 (including 100 including fractures) for the CRF and QUS alone versus the combination score.

CONCLUSIONS

Combining clinical risk factors to heel bone ultrasound appears to correctly identify more women at low risk for hip fracture than either the stiffness index or the CRF alone; it improves the detection of women both at low and high risk.

The use of clinical risk factors enhances the performance of BMD in the prediction of hip and osteoporotic fractures in men and women

BMD and clinical risk factors predict hip and other osteoporotic fractures. The combination of clinical risk factors and BMD provide higher specificity and sensitivity than either alone. INTRODUCTION AND HYPOTHESES: To develop a risk assessment tool based on clinical risk factors (CRFs) with and without BMD.

METHODS

Nine population-based studies were studied in which BMD and CRFs were documented at baseline. Poisson regression models were developed for hip fracture and other osteoporotic fractures, with and without hip BMD. Fracture risk was expressed as gradient of risk (GR, risk ratio/SD change in risk score).

RESULTS

CRFs alone predicted hip fracture with a GR of 2.1/SD at the age of 50 years and decreased with age. The use of BMD alone provided a higher GR (3.7/SD), and was improved further with the combined use of CRFs and BMD (4.2/SD). For other osteoporotic fractures, the GRs were lower than for hip fracture. The GR with CRFs alone was 1.4/SD at the age of 50 years, similar to that provided by BMD (GR = 1.4/SD) and was not markedly increased by the combination (GR = 1.4/SD). The performance characteristics of clinical risk factors with and without BMD were validated in eleven independent population-based cohorts.

CONCLUSIONS

The models developed provide the basis for the integrated use of validated clinical risk factors in men and women to aid in fracture risk prediction.

Clinical risk factors for fracture in postmenopausal Canadian women: a population-based prevalence study

Clinical risk factor assessment can be used to enhance fracture risk estimation based upon bone densitometry alone. Population- and age-specific risk factor prevalence data are required for the construction of these risk models. Our objective was to derive population-based prevalence estimates of specific clinical risk factors for postmenopausal women resident in the Province of Manitoba, Canada. A random sample of 40,300 women age 50 or older identified from the provincial health plan was mailed a validated self-report risk factor survey. The response rate was 8747 (21.7%) with a final study population of 8027 women after exclusions. The individual prevalence for each clinical risk factor ranged from 5.8% for hyperthyroidism to 33.0% for a fall in the preceding 12 months. Most point prevalence estimates were similar to other large cohort studies, though the prevalences of inactivity and poor mobility were higher than expected while height at age 25 and the prevalence of any fracture after age 50 were lower than expected. Most of the respondents (86.9%) had at least one non-age clinical risk factor, 60.6% had two or more, and 33.5% had three or more. Age affected risk factor prevalence, and older age was associated with a higher rate of multiple risk factors. The availability of age-specific risk factor prevalence rates in this population may allow for more accurate fracture risk modeling.

Prediction and discrimination of osteoporotic hip fracture in postmenopausal women

Osteoporotic hip fractures increase dramatically with age and are responsible for considerable morbidity and mortality. Several treatments to prevent the occurrence of hip fracture have been validated in large randomized trials and the current challenge is to improve the identification of individuals at high risk of fracture who would benefit from therapeutic or preventive intervention. We have performed an exhaustive literature review on hip fracture predictors, focusing primarily on clinical risk factors, dual X-ray absorptiometry (DXA), quantitative ultrasound, and bone markers. This review is based on original articles and meta-analyses. We have selected studies that aim both to predict the risk of hip fracture and to discriminate individuals with or without fracture. We have included only postmenopausal women in our review. For studies involving both men and women, only results concerning women have been considered. Regarding clinical factors, only prospective studies have been taken into account. Predictive factors have been used as stand-alone tools to predict hip fracture or sequentially through successive selection processes or by combination into risk scores. There is still much debate as to whether or not the combination of these various parameters, as risk scores or as sequential or concurrent combinations, could help to better predict hip fracture. There are conflicting results on whether or not such combinations provide improvement over each method alone. Sequential combination of bone mineral density and ultrasound parameters might be cost-effective compared with DXA alone, because of fewer bone mineral density measurements. However, use of multiple techniques may increase costs. One problem that precludes comparison of most published studies is that they use either relative risk, or absolute risk, or sensitivity and specificity. The absolute risk of individuals given their risk factors and bone assessment results would be a more appropriate model for decision-making than relative risk. Currently, a group appointed by the World Health Organization and lead by Professor John Kanis is working on such a model. It will therefore be possible to further assess the best choice of threshold to optimize the number of women needed to screen for each country and each treatment.

Simple Computer Model for Calculating and Reporting 5-Year Osteoporotic Fracture Risk in Postmenopausal Women

PURPOSE

To devise, validate, and test a software model that improves how clinicians calculate individual risk for osteoporotic fracture and expected treatment benefit.

METHODS

We developed a simple model of seven easily ascertained items plus bone mineral density (BMD) that calculates absolute fracture risk and expected absolute risk reduction after treatment. Baseline clinical variables and longitudinal fracture data from two large osteoporosis cohort studies validated the model's accuracy in predicting fracture risk. We then surveyed 298 clinicians to evaluate the likelihood they would prescribe alendronate in three hypothetical cases, first given the clinical data alone and then with model-derived data on fracture risk and expected treatment benefit.

RESULTS

We found a strong linear relationship with the model's predicted fracture risk and observed fracture rates in two large observational cohorts but the model overestimated risk 2-3 fold. The model predicted a 1:200 5-year risk for spinal fracture and a 1:40 risk for nonspinal fracture in an index case of a younger, thin, osteopenic woman. Given this hypothetical history with BMD t-scores, 26% of clinicians were likely to prescribe alendronate; when also given model-calculated 5-year fracture risks with or without treatment, only 13% were likely to prescribe alendronate (p < 0.001). For 2 other osteoporosis patients in whom risk was much higher, further information on fracture risk and expected treatment benefit did not alter prescribing.

CONCLUSIONS

Reporting absolute fracture risk with and without treatment promises to be most useful in women with osteopenia, a common clinical dilemma in younger postmenopausal women.

Establishing a regional bone density program: lessons from the Manitoba experience

In 1997, the province of Manitoba, Canada developed a regional bone density program to address concerns related to access, waiting times, and quality assurance. We report our experience with this model of bone density service delivery, which is unique in North America, and confront the challenge of balancing accessibility, clear guidelines, and fiscal responsibility.