Advice
The technology
The technology
Bindex (Bone Index Finland OY) is a pulse‑echo ultrasound tool for the screening and diagnosis of osteoporosis. The device measures cortical bone thickness at the upper shaft of the tibia and calculates a density index from this measure alongside other clinical risk factors or patient characteristics. The density index is an estimate of hip bone mineral density (BMD). Bindex provides a way to stratify the risk of osteoporosis using thresholds for diagnosis recommended by the International Society for Clinical Densitometry (ISCD) and National Osteoporosis Society.
The handheld Bindex device is a transducer that can be connected to a computer or Windows tablet, through a USB cable. A custom ruler is used to measure to a point one third of the length of the proximal tibia from the knee joint, where the Bindex ultrasound measurement will be taken. Ultrasound gel is applied to the measurement site and the hardware is calibrated using the Bindex software. To take a measurement, the transducer is moved over the measurement site for a few minutes. Cortical thickness is estimated by multiplying the speed of sound by the time lag between ultrasound echoes from the front and back surfaces of the cortical bone layer. The transducer collects the sound waves reflected from the bone and transmits the signal to the connected computer, which immediately displays the results using the Bindex software. The Bindex measurement typically takes under 15 minutes to do.
Bindex software uses the cortical thickness measurement plus age, weight and height of the person being measured, to calculate the density index. These values are displayed alongside pre-determined density index thresholds that estimate the probability of osteoporosis. Results are displayed using a 'traffic light' colour bar; green shows a low probability of osteoporosis and a low need for further investigation, yellow shows that more investigations are needed, and red shows a high risk of osteoporosis and a need for treatment without dual‑energy X‑ray absorptiometry (DXA). Results are saved in the Bindex database on the computer and can be exported in a PDF format.
Innovations
Bindex is a pocket-sized ultrasound that can be connected and used with any laptop or desktop computer's USB socket. Unlike other quantitative ultrasound that measures sound speed and attenuation in the heel, Bindex measures the tibia, and applies thresholds of 90% sensitivity and specificity compared with axial DXA, which are designed to guide further tests and treatment for osteoporosis.
Current NHS pathway
NICE guidance on osteoporosis recommends that fracture risk should be assessed using the World Health Organisation's fracture risk assessment tool (FRAX) or the QFracture questionnaire, which is a web calculator designed to calculate the risk of developing an osteoporotic fracture. People whose fracture risk assessment result is above a threshold for intervention should have their BMD (typically hip and lower spine [NHS Choices 2016]) measured using DXA. The BMD value can be used to recalculate FRAX to get an absolute risk value.
The intervention threshold for a proposed treatment is based on other guidelines, such as ISCD's guidelines for peripheral dual-energy X-ray absorptiometry in the management of osteoporosis.
If adopted into the current NHS pathway, Bindex could be used after FRAX or QFracture assessment, in people with suspected osteoporosis. People with a high or intermediate risk classification based on FRAX would be scanned using Bindex. People whose Bindex scan gave a density index value that showed a high risk of osteoporosis would then be referred for osteoporosis treatment, without needing a DXA scan. Only people whose Bindex scan gave a density index value indicating an intermediate risk of osteoporosis would be referred for a DXA scan.
NICE is aware of 1 CE‑marked device (and 5 similar devices in development) that appear to fulfil a similar function as Bindex:
-
OsCare Sono (Oscare Medical Oy).
Population, setting and intended user
Bindex is designed to help guide further investigations and treatment in people who may have osteoporosis. It could be used in the primary, secondary or home care setting (for example, on a home visit). Bindex would be used by a trained healthcare professional, likely to include GP practice nurses in primary care and community nurses. Training is needed before using the device.
Costs
Technology costs
The cost of the Bindex device is based on the software licence and varies depending on the number of analyses needed. Table 1 shows the cost per measurement, based on the manufacturer's estimated lifespan of the equipment of 5 years.
Table 1 Cost by licence type
|
Type of licence |
Cost |
Cost per diagnostic session |
|
300 analyses |
£4,000 |
£13.30 |
|
500 analyses |
£6,000 |
£12.00 |
|
1,000 analyses |
£10,000 |
£10.00 |
Assuming that the Bindex would be used by a community nurse specialist (band 6) or a GP practice nurse, the cost of a 15‑minute appointment would be about £16 and £9, respectively (Personal Social Services Research Unit 2016).
Costs of standard care
In cases of suspected osteoporosis (NHS Choices 2016), a GP uses a free online or paper-based risk assessment tool such as FRAX or QFracture; they may also refer the patient for a DXA scan. The resource use associated with a community nurse specialist or GP contact for an hour is valued at £65 and £236 respectively (Personal Social Services Research Unit 2016). Therefore, the cost of a 15‑minute appointment would be £16 (with a community nurse specialist) or £59 (with a GP). The average unit cost of a DXA scan is about £61 (code RD50Z, NHS reference costs 2015).
Resource consequences
Bindex does not need servicing or regular maintenance, as long as it passes self-calibration, which is done as a part of each analysis. No extra equipment is needed other than a working computer and standard ultrasound gel. No other practical difficulties have been identified in using or adopting the technology.
A poster presentation of a model-based cost-effectiveness analysis comparing a diagnostic strategy with Bindex to one without (Asseburg et al. 2013) was found during the systematic review of economic evidence. A Finnish societal perspective was used and the model duration was 10 years. The theoretical model was evaluated for 5 patient cohorts: women with a BMI of 24, aged 65 years with previous fracture, and aged 75 years or 85 years with and without previous fracture. Fractures included wrist, vertebral, hip and other fractures.
Two strategies were compared. First, a standard of care strategy: FRAX and BMI assessment, followed by no treatment or DXA scan and then treatment or no treatment. This was compared with a second 'using Bindex' strategy: FRAX with BMI assessment, followed by no treatment or Bindex (and after Bindex: no treatment, DXA scan and treatment, or DXA scan and no treatment). Differences in cost effectiveness could be the result of differences in technology costs and the differences of specificity and sensitivity in the diagnostic pathways.
The screening cost saved in the Bindex strategy averaged €230 per patient (about £179 after adjusting for inflation and converting to pound sterling) across all cohorts. The Bindex strategy was relatively cost saving in all cohorts compared with the standard of care.