We lack effective diagnostics of osteoporosis at the primary health care level. An ultrasound device was used to identify subjects in the osteoporotic range as defined by DXA. A case finding strategy combining ultrasound results with DXA measurements for patients with intermediate ultrasound results is presented.
We lack effective screening and diagnostics of osteoporosis at primary health care. In this study, a pulse-echo ultrasound (US) method is investigated for osteoporosis screening.
A total of 1091 Caucasian women (aged 50–80 years) were recruited for the study and measured with US in the tibia and radius. This method measures cortical thickness and provides an estimate of bone mineral density (BMD) and density index (DI). BMD assessment of the hip was available for 988 women. A total of 888 women had one or more risk factors for osteoporosis (OPsusp), and 100 women were classified healthy. Previously determined thresholds for the DI were evaluated for assessment of efficacy of the technique to detect hip BMD at osteoporotic range (T-score at or below − 2.5).
In the OPsusp group, the application of thresholds for the DI showed that approximately 32%of the subjects would require an additional DXA measurement. The multi-site ultrasound (US) measurement-based DI showed 93.7% sensitivity and 81.6% specificity, whereas the corresponding values for single-site US measurement-based DI were 84.7 and 82.0%, respectively. The ultrasound measurements showed a high negative predictive value 97.7 to 99.2%in every age decade examined (ages 50–59, 60–69, 70–79 years).
The study data demonstrate that a strategy of combining ultrasound measurement with added DXA measurements in cases with intermediate ultrasound results (about 30%) can be useful for identifying subjects at risk for a low bone mineral density in the osteoporotic range.
Pulse-echo ultrasonometry can be used as a pre-screen for hip osteoporosis before dual-energy x-ray absorptiometry (DXA), potentially allowing DXA to be avoided for the majority of post-menopausal women. Pulse-echo ultrasound measures of tibia cortical thickness are also associated with radiographically confirmed prior fractures, independent of femoral neck bone mineral density.
Five hundred fifty-five post-menopausal women age 50 to 89 had femoral neck and total hip BMD measured by dual-energy x-ray absorptiometry (DXA), and pulse-echo ultrasound measures of distal radius, proximal tibia, distal tibia cortical thickness, and multi- and single-site density indices (DI). Using previously published threshold ultrasound values, we estimated the proportion of women who would avoid a follow-up DXA after pulse-echo ultrasonometry, and the sensitivity and specificity of this for the detection of hip osteoporosis. Logistic regression models were used to estimate the associations of pulse-echo ultrasound measures with radiographically confirmed clinical fractures within the prior 5years.
Using multi-site and single-site DI measures, follow-up DXA could be avoided for 73 and 69% of individuals, respectively, while detecting hip osteoporosis with 80-82% sensitivity and 81% specificity. Radiographically confirmed prior fracture was associated with ultrasound measures of single-site DI (odds ratio (OR) 1.55, 95% confidence interval (CI). 1.06 to 2.26) and proximal tibia cortical thickness (OR 1.47, 95% CI 1.10 to 1.96), adjusted for age, body mass index, and femoral neck BMD.
Pulse-echo ultrasonometry can be used as an initial screening test for hip osteoporosis. Prospective studies of how well pulse-echo ultrasound measures predict subsequent clinical fractures are warranted.
A new ultrasound based point of care device (Bindex®) has been recently introduced for osteoporosis (OP) screening and diagnostics at primary healthcare. Bindex® measures cortical thickness and determines parameter called density index (DI). Thresholds (90% sensitivity and specificity, triage approach) for DI in OP assessment have been determined in Finnish Caucasian population along the International Society of Clinical Densitometry (ISCD) guidelines. In this study, the sensitivity and specificity are assessed in data set combining three independent trials.
A total of 1830 Caucasian females participated the study (age 67.2 ± 8.9 years). Subjects were measured with dual energy x-ray absorptiometry (DXA) to determine bone mineral density (BMD) at proximal femur. Further, the cortical thickness was measured at three locations (distal radius, distal and proximal tibia) with Bindex®. Subjects were diagnosed with OP when T-score at femoral neck or total proximal femur was below -2.5 (NHANES III reference database). A subgroup of 1344 subjects was formed in which the subjects with T-score -2.1 - -2.9 were removed due to the precision error in T-score values and uncertainty of osteoporosis/healthy status. In this subgroup, OP was diagnosed when T-score was at or below -2.9. Density index was calculated either by using measurement at one location (DI1, proximal tibia) or all three locations (DI3).
A total of 70 to 73% of the subjects could be directly diagnosed by using Bindex® measurement. Sensitivity in OP diagnostics was 82% and 87% for DI1 and DI3, respectively. Specificity was 83% for both DI1 and DI3. In the subgroup, sensitivity in OP diagnostics was 90% and 93% for DI1 and DI3, respectively. Specificity was 87% for both DI1 and DI3.
The suggested thresholds for the DI were tested in a large population and performance of the technique seems consistent when data from several studies were combined. The ultrasound based Bindex measurement for osteoporosis detection shows good performance for OP detection at primary care level.
Due to the lack of diagnostics in primary health care, over 75% of osteoporotic patients are not diagnosed. A new ultrasound method for primary health care is proposed. Results suggest applicability of ultrasound method for osteoporosis diagnostics at primary health care.
A total of 572 Caucasian women (age 20 to 91years) were examined using pulse-echo US measurements in the tibia and radius. This method provides an estimate of bone mineral density (BMD), i.e. density index (DI). Areal BMD measurements at the femoral neck (BMDneck) and total hip (BMDtotal) were determined by using axial dual-energy X-ray absorptiometry (DXA) for women older than 50years of age (n = 445, age = 68.8 ± 8.5years). The osteoporosis thresholds for the DI were determined according to the International Society for Clinical Densitometry (ISCD). Finally, the FRAX questionnaire was completed by 425 participants.
Osteoporosis was diagnosed in individuals with a T-score -2.5 or less in the total hip or femoral neck (n = 75). By using the ISCD approach for the DI, only 28.7% of the subjects were found to require an additional DXA measurement. Our results suggest that combination of US measurement and FRAX in osteoporosis management pathways would decrease the number of DXA measurements to 16% and the same treatment decisions would be reached at 85.4% sensitivity and 78.5% specificity levels.
The present results demonstrate a significant correlation between the ultrasound and DXA measurements at the proximal femur. The thresholds presented here with the application to current osteoporosis management pathways show promise for the technique to significantly decrease the amount of DXA referrals and increase diagnostic coverage; however, these results need to be confirmed in future studies.
In this study, Bindex® is compared to axial DXA in terms of health economic efficiency (incremental cost-effectiveness).
The average screening cost saved with Bindex® technique is 230€.
If Bindex® screening were included in the Finnish care pathway, costs would be saved compared to the current pathway. Moreover, Bindex® screening can be shown to be cost-effective compared to current practice.