Authors' objectives: Peripheral artery disease is a common condition caused by narrowing/blockage of the arteries, resulting in reduced blood supply. Peripheral artery disease is associated with an increased risk of vascular complications, but early treatment reduces mortality and morbidity. Leg ulcers are long-lasting wounds, usually treated by compression therapy. Compression therapy is not suitable for people with peripheral artery disease, as it can affect the arterial blood supply. In clinical practice, people with peripheral artery disease are identified by measurement of the ankle–brachial pressure index using a sphygmomanometer and manual Doppler device. However, this method can be uncomfortable for people with leg ulcers and automated devices have been proposed as a more acceptable alternative. The objective of this appraisal was to summarise the clinical and cost-effectiveness evidence on the use of automated devices to detect peripheral artery disease in people with leg ulcers. Peripheral artery disease (PAD) is a highly prevalent atherosclerotic condition characterised by the narrowing of the peripheral arteries resulting in restriction of blood supply to the affected limb. Although PAD is frequently asymptomatic, it can cause complications that can range from intermittent claudication (pain on walking which is relieved by rest) to critical limb ischaemia. Up to one-quarter of people with symptomatic PAD may require intervention, and amputation may be necessary if it is left untreated. Leg ulcers are defined as wounds that occur below the knee and either on or above the ankle (malleolus). Compression treatment (bandages or stockings) is recommended to treat venous leg ulcers, and there is a robust evidence base to support its effectiveness. However, compression therapy should be avoided in people with leg wounds and symptoms of arterial insufficiency, as compression may cause damage by impairing the arterial supply to the ulcerated leg. To improve PAD diagnosis and decide the most suitable treatment, people with leg ulcers are assessed using ankle–brachial pressure index (ABPI) measurements. ABPI is usually measured using a sphygmomanometer and manual Doppler device, which requires expertise from the relevant operator/healthcare professional. The procedure can be protracted and unpleasant for those with leg ulcers. Automated devices may be advantageous in reducing the length of time taken to assess ABPI and, thereby, any associated discomfort for the patient. In addition, automated devices may potentially be more accurate than manual processes in detecting PAD, thus conferring additional benefits such as reduced time to treatment and improved outcomes for people with leg ulcers. The specific objectives of this assessment were to: Determine the diagnostic performance and clinical utility of automated devices available in United Kingdom (UK) clinical practice [BlueDop Vascular Expert (BlueDop Medical), boso ABI-system 100 (BOSCH + SOHN), WatchBP Office ABI (Microlife), WatchBP Office Vascular (Microlife)], MESI ABPI MD (MESI), MESI mTABLET ABI (MESI), Dopplex Ability Automatic ABI System (Huntleigh Healthcare) for assessing the presence of PAD in people with leg ulcers. Develop an economic model to assess the cost-effectiveness of the automated devices available in UK clinical practice for assessing the presence of PAD in people with leg ulcers.

Authors' results and conclusions:   Nature, description and quality of the available evidence The database searches identified 110 unique records, 79 records were supplied by the respective companies and 2 further studies were identified from reference lists. Twenty-four studies, published in 26 papers, were included in the systematic review of clinical effectiveness. Two studies enrolled specifically people with leg ulcers (167 participants in total) while the remaining studies (4258 participants in total) included people from primary care practices, cardiovascular risk services, vascular services and from epidemiological/general population-based studies. All studies used an ABPI threshold of 0.9. In healthy people, ABPI would be expected to be > 0.9. Most of the studies assessed the performance of a single automated device with only one study comparing two devices (WatchBP and MESI ABPI MD). Regarding the type of automated devices, two studies provided data on the BlueDop Vascular Expert device, four studies on the BOSO ABI-System 100, six studies on the Dopplex Ability, eight studies on the MESI ABPI MD and five studies on the WatchBP Office. No studies assessed the performance of the WatchBP Office Vascular and the MESI mTABLET ABI devices. Apart from one study conducted in New Zealand, all included studies were conducted in Europe (six in the UK). The risk of bias of included studies was assessed using the QUADAS-2 tool. Most studies were judged at low risk for the index test domain and at unclear risk for the patient selection, reference standard and flow and timing domains. The risk of applicability concerns was low in most studies. Future research is needed to evaluate the use of automated devices within specific populations (people with leg ulcers) and relevant settings. For the broader use of automated devices in clinical practice, more robust evidence is required to establish whether the use of automated devices is appropriate and cost-effective for the general screening of clinical populations with any vascular concerns. In addition, evidence is needed to support the use of automated devices as an alternative or adjunct to manual Doppler in people with symptoms of PAD.

Authors' methods:   The limited evidence identified for each automated device, especially in people with leg ulcers, and its clinical heterogeneity precludes any firm conclusions on the diagnostic performance and cost-effectiveness of these devices in clinical practice. Clinical effectiveness Comprehensive electronic searches of databases including MEDLINE, EMBASE, Cochrane Library Web of Science and CINAHL were conducted to identify relevant reports of published studies. Evidence was considered from studies of any design assessing the relevant automated devices versus standard clinical assessment using a manual Doppler device. Initially, the population of interest was people with leg ulcers requiring measurement of ABPI, but, due to the dearth of available evidence, it was broadened to any population receiving ABPI measurement. Data on the diagnostic performance of the automated devices including data on the level of agreement between ABPI readings from automated devices and those from the reference device were extracted from the included studies. Information on the use of the devices in clinical practice was also recorded. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies – version 2 (QUADAS-2), QUADAS-C and the Review Body for Interventional Procedures (ReBIP) checklists, according to the type of study design. For each device, when sufficient data were available, we conducted random-effects meta-analyses using a Hierarchical Summary Receiving Operating Characteristic (HSROC) model. A two-stage, de novo decision analysis model was developed to assess cost-effectiveness. The first part was a decision tree model, which used a linked-evidence approach to capture the impact of test diagnostic accuracy on expected costs and quality-adjusted life-years (QALYs) for the first 24 weeks following test use. This included delayed venous ulcer healing due to false-positive (FP) test results (indicating PAD when the ulcer was venous) and increased risk of requiring invasive arterial treatment for inappropriately compressed arterial/mixed ulcers following a false-negative (FN) test result (indicating venous when underlying disease was arterial/mixed). It was assumed that any inaccurate tests would be identified within the 24-week time horizon of the decision tree. The surviving proportion of the cohort then entered arterial, mixed or venous ulcer Markov models depending on their true underlying disease classification. The venous disease model included five mutually exclusive health states, centred around ulcer healing (healed index ulcer, unhealed index ulcer, recurrence, healed post recurrence and death). The arterial and mixed disease models included four health states, focusing on the long-term outcomes of the arterial component of disease [critical limb ischaemia (CLI), healed post CLI, amputation and death]. The decision to structure the mixed Markov model similarly to the arterial-only model was based on discussion with clinical experts who explained that, in clinical practice, the arterial component of disease is likely to take priority in the patient’s care pathway. Costs were based on National Health Service and Personal Social Service perspective costs (2021 values) and included: micro-costing of the automated and manual Doppler devices costs of applying compression for the unhealed duration of a venous ulcer costs of referral to vascular services for test-positive patients, including the additional costs of unnecessary referral for patients with a FP test result costs of treating arterial disease, including endovascular and bypass procedures as well as follow-up nursing care long-term follow-up costs in the Markov model included the cost of managing recurrent venous ulcers, recurrent CLI and long-term health and social care costs of amputation. Health state utility values were obtained from the literature and were based on EuroQol-5 Dimensions data, valued using the UK value set where possible. Utilities were combined with mortality estimates for each health state to calculate QALYs. In the decision tree, utilities were dependent on the duration of ulcer healing time for venous ulcers, and whether patients had CLI for those with arterial/mixed disease. All utilities were adjusted for UK age- and sex-specific general population norms, allowing the cohort to experience reduced utility as they aged over subsequent model cycles. Expected costs and QALYs were accumulated over a lifetime horizon, in 6-monthly cycles and an annual discount rate of 3.5% per annum was applied to future costs and QALYs. Probabilistic analyses (Monte Carlo simulation with 1000 draws for each parameter) were conducted for a range of pessimistic and optimistic alternative base-case scenarios. A full range of deterministic scenarios explored the impact of alternative sources of model inputs and assumptions on cost-effectiveness results.

Project Status: Completed

URL for project: https://www.journalslibrary.nihr.ac.uk/programmes/hta/NIHR135478

Year Published: 2024

URL for published report: https://www.journalslibrary.nihr.ac.uk/hta/TWCG3912

URL for additional information: English

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: England, United Kingdom

DOI: 10.3310/TWCG3912

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk