Comparison between T-score-based diagnosis of osteoporosis and specific skeletal site measurements: prognostic value for predicting fracture risk

Fatty infiltration of the multifidus muscle independently increases osteoporotic vertebral compression fracture risk

BACKGROUND

Vertebral compression fractures decrease daily life activities and increase economic and social burdens. Aging decreases bone mineral density (BMD), which increases the incidence of osteoporotic vertebral compression fractures (OVCFs). However, factors other than BMD can affect OVCFs. Sarcopenia has been a noticeable factor in the aging health problem. Sarcopenia, which involves a decrease in the quality of the back muscles, influences OVCFs. Therefore, this study aimed to evaluate the influence of the quality of the multifidus muscle on OVCFs.

METHODS

We retrospectively studied patients aged 60 years and older who underwent concomitant lumbar MRI and BMD in the university hospital database, with no history of structurally affecting the lumbar spine. We first divided the recruited people into a control group and a fracture group according to the presence or absence of OVCFs, and further divided the fracture group into an osteoporosis BMD group and an osteopenia BMD group based on the BMD T-score of -2.5. Using images of lumbar spine MRI, the cross-sectional area and percentage of muscle fiber (PMF) of the multifidus muscle were obtained.

RESULTS

We included 120 patients who had visited the university hospital, with 45 participants in the control group and 75 in the fracture group (osteopenia BMD: 41, osteoporosis BMD: 34). Age, BMD, and the psoas index significantly differed between the control and fracture groups. The mean cross-sectional area (CSA) of multifidus muscles measured at L4-5 and L5-S1, respectively, did not differ among the control, P-BMD, and O-BMD groups. On the other hand, the PMF measured at L4-5 and L5-S1 showed a significant difference among the three groups, and the value of the fracture group was lower than that of the control group. Logistic regression analysis showed that the PMF value, not the CSA, of the multifidus muscle at L4-5 and L5-S1 affected the risk of OVCFs, with and without adjusting for other significant factors.

CONCLUSIONS

High percentage of fatty infiltration of the multifidus muscle increases the spinal fracture risk. Therefore, preserving the quality of the spinal muscle and bone density is essential for preventing OVCFs.

Validation of osteoporosis risk assessment tools in middle-aged Thai women

OBJECTIVES

To validate osteoporosis risk assessment tools in middle-aged Thai women.

METHODS

A total of 1038 women who had bone mineral density (BMD) measurements using dual-energy X-ray absorptiometry were reviewed. Clinical data were used to validate the diagnostic test performance of various osteoporosis risk assessment tools, including ABONE, FRAX^®, ORAI, OSIRIS, SCORE, SOFSURF, and OSTA. The following parameters were evaluated: sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy; those with 95% confidence interval (CI) of the receiver operator characteristics area under the curve (ROC-AUC) > 0.5 were considered statistically significant.

RESULTS

The subjects had a mean age of 53.01 ± 6.20 years and body mass index (BMI) of 23.98 ± 3.38 kg/m². Among the osteoporosis risk assessment tools being evaluated, the tools that had ROC-AUC >0.8 and 95% CI >0.5, and could predict osteoporosis at the femoral neck with high specificity of >75% and NPV of >90%, were FRAX^® without BMD (ROC-AUC 0.83; 95% CI 0.73-0.93; specificity 99.90; NPV 98.89), SCORE (ROC-AUC 0.86; 95% CI 0.78-0.94; specificity 98.79; NPV 98.99), and OSTA (ROC-AUC 0.86; 95% CI 0.79-0.94; specificity 75.03; NPV 99.73).

CONCLUSION

The prevalence of osteoporosis in the middle-aged Thai women attending Siriraj Menopause Clinic is 7.3% at the lumbar spine and/or femoral neck. FRAX^® without BMD, SCORE, and OSTA have appropriate validity as tools for ruling out osteoporosis in these women.

Clinical risk indices, prediction of osteoporosis, and prevention of fractures: diagnostic consequences and costs

The primary aim of this study was to validate the Osteoporosis Self-Assessment Tools for Asians (OSTA) instrument in Thai women, and to evaluate its utility in terms of economic costs and fracture prediction. Femoral neck and lumbar spine BMD was measured by dual energy X-ray absorptiometry in 322 Thai women, aged 60+/-10 years (mean+/-SD; range: 45-84 years). The women were classified as having osteoporosis if their BMD T-scores were < or =-2.5. The OSTA score was calculated for each woman using her age and weight according to the formula: 0.2(weight-age). Women with OSTA scores < or =-1 and >-1 were classified as "high risk" and "low risk," respectively. The prevalence of osteoporosis was 33% by femoral neck or lumbar spine BMD. Using the OSTA score, 165 (51.2%) women were classified as high risk. The sensitivity, specificity and positive predictive value of OSTA was 82% 64% and 53%, respectively. If the OSTA score is used to identify women with high risk of fracture, and assuming that the incidence of fracture among osteoporotic and non-osteoporotic women are 2% and 1% per year, respectively, the OSTA score can identify 59% of fracture cases correctly, and 41% are expected to be missed. Furthermore, if the high-risk subjects identified by OSTA are to be treated, and if the treatment reduces fracture incidence by 50%, and assuming that the treatment cost is $1 per day, then the cost to prevent one fracture is estimated to be $48,530. Results of this study suggest that, in the Thai population, the OSTA score had high sensitivity but low specificity and low positive predictive value in the identification of osteoporotic women. Its use in the general population can result in a high false-positive rate and incur significant cost to the community.

Clinical risk factor evaluation to defer postmenopausal women from bone mineral density measurement: an Italian study

To identify clinical risk factors (CRFs) best related to low bone mineral density (BMD) and to assess their abilityin deferring women from dual-energy X-ray absorptiometry (DXA), 1187 Italian postmenopausal women, dividedinto development (709) and validation (478) groups, were studied. CRFs were investigated by questionnaire. DXAwas performed at the spine and femoral neck. A T-score < -2.5 at both measurement sites classified those with lowBMD. In the development group, using the logistic regression, the CRFs best predicting low BMD were years sincemenopause, age at menarche, weight, previous fracture, and muscle weakness. The predicted probability of low BMD(PPL-BMD), calculated by the logistic equation, was used to build receiver-operating characteristic (ROC) curves(area = 0.786, standard error [SE] = 0.017) on diagnosed BMD status. The PPL-BMD cutoff below which to deferwomen from DXA was set corresponding to the ROC curve sensitivity of 99%, 98%, and 97%. The coefficients ofthe logistic regression were then used to calculate the PPL-BMD of the validation group. In the validation group, theoverall ability of CRFs to predict low BMD (ROC area = 0.744, SE = 0.023) was not different from that of the developmentgroup. At the PPL-BMD cutoff of 0.132, the percentage of DXA-deferred cases (14.5% vs 19.0%) and low-BMD-missed cases (0.7% vs 1.7%) was similar in both groups. The rates of DXA-deferred women by CRFs arereproducible and this tool should be useful in clinical practice.

Comparison of T-scores from different skeletal sites in differentiating postmenopausal women with and without prevalent vertebral fractures

It is not clear how bone mineral density (BMD) measurements from several regions of lumbar spine and proximal femur should be utilized in assessing fracture risk. We examined how well the newest ISCD recommendations differentiate subjects with and without prevalent vertebral fractures in 187 postmenopausal women presenting for routine bone densitometry. The association between T-scores from proximal femur and lumbar spine sites and the probability of having a vertebral fracture was modeled via logistic regression with adjustment for age. The lowest T-score of any hip or spine sites (the current ISCD recommendation) and the proximal femur measurements, particularly the femoral neck and total hip, displayed the strongest association with the probability of vertebral fractures.Subjects with a T-score < -2.5 at multiple hip sites had a higher probability of having a vertebral fracture. The sensitivity and specificity associated with particular T-score cutoff values varied greatly depending on the site of measurement.Consequently, T-score values from different sites that had comparable sensitivity/specificity for detecting the presence of vertebral fractures differed by as much as 1.5 T-score units. This finding implies that a single cutoff value, such as -2.5, might not be clinically acceptable when applied to T-scores from different sites.

Influence of image-capturing parameters on digital X-ray radiogrammetry

The purpose of this study was to evaluate the importance of different image-capturing conditions, which might influence the characteristics of radiographs and, consequently, impact calculations of bone mineral density (BMD) and Metacarpal Index (MCI) using digital X-ray radiogrammetry (DXR). Radiographs of the left hand of deceased males were acquired three times using systematically varied parameters: 4-8 miliamp seconds (mA); 40-52 kV; film-focus distance (FFD); 90-130 cm; film sensitivity, 200/400; and different image modalities (conventional vs original digital radiographs as well as digital printouts). Furthermore, the interradiograph reproducibility using both conventional equipment and printouts vs originals of digital images and the intraradiograph reproducibility (either conventional or digital printouts) were evaluated. All BMD and MCI measurements were obtained with the DXR technology. The interradiograph reproducibility of DXR-BMD using conventional images under standardized conditions (6 mAs; 42 kV; 1 m FFD; film sensitivity of 200) was calculated to be coefficient of variation (CV) = 0.49% for Agfa Curix film and CV = 0.33% for Kodak T-MAT-Plus film, whereas reproducibility error using digital images ranged from CV = 0.57% (digital printouts; Philips) to CV = 1.50% (original digital images; Siemens). The intraradiograph reproducibility error was observed to be CV = 0.13% (conventional; Kodak film) vs CV = 0.27% (digital printouts; Philips). The BMD calculation was not noticeably affected by changes of FFD, exposure level, or film sensitivity/film brand, but was influenced by tube voltage (CV = 0.99% for Kodak film to CV = 2.05% for Siemens digital printouts). No significant differences were observed between the BMD and MCI data. DXR provides measurements of MCI and BMD with high precision and reproducibility. The measurements are unaffected by all tested image-capturing conditions, with the exception of tube voltage. In addition, different digital image devices clearly have an effect on DXR reproducibility.