Automated devices for identifying peripheral arterial disease in people with leg ulceration: an evidence synthesis and cost-effectiveness analysis.

ABSTRACT

Background: 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. Methods: . Clinical effectiveness To identify reports of relevant studies, we searched major electronic databases and scrutinised the information supplied by the manufacturers of the automated devices under investigation. Due to the lack of evidence on people with leg ulcers, we considered evidence from studies of any design assessing automated devices versus an acceptable reference device in any population receiving ankle-brachial pressure index assessment. We summarised information on diagnostic accuracy of the automated devices and level of agreement with the reference device. For each device, when data permit, we pooled data across studies by conducting random-effects meta-analyses using a Hierarchical Summary Receiving Operating Characteristics model. Cost-effectiveness An economic model comprising a decision tree (24 weeks) and Markov models to capture lifetime costs and quality-adjusted life-years associated with venous, arterial and mixed aetiology disease in leg ulcer patients. Analyses were conducted from a United Kingdom National Health Service and Personal Social Services perspective. Costs and quality-adjusted life-years were discounted at 3.5% per year. Deterministic and several probabilistic analyses were used to capture uncertainty surrounding a range of optimistic and pessimistic assumptions about the impact of automated tests on health outcomes (ulcer healing and requirement for invasive management of arterial disease). Results: . Clinical effectiveness From the 116 records retrieved by the electronic searches, we included 24 studies evaluating five devices (BlueDop Vascular Expert, BOSO ABI-System 100, Dopplex Ability, MESI ankle-brachial pressure index MD and WatchBP Office ABI). Two studies assessing people with leg ulcers found that automated devices often gave higher ankle-brachial pressure index readings than manual Doppler (underestimation of arterial disease). In the 22 studies involving people without leg ulcers, automated devices generally demonstrated good specificity and moderate specificity. Meta-analysis of 12 studies showed a pooled sensitivity of 64% (95% confidence interval 57% to 71%) and a pooled specificity of 96% (95% confidence interval 92% to 98%) for detection of peripheral artery disease. Cost-effectiveness Automated devices cost less than manual Doppler to deliver. However, increased risks of invasive treatment requirements for inappropriately compressed arterial/mixed ulcers due to false-negative results, and increased healing times due to delayed compression of false-positive test results mean that in most scenarios manual Doppler was less costly and had slightly higher quality-adjusted life-years than automated devices. Results are highly uncertain, dependent on many assumptions and should be interpreted cautiously. Limitations and conclusions: 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. Study registration This study is registered as PROSPERO CRD42022327588. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Evidence Synthesis programme (NIHR award ref NIHR135478) and is published in full in Health Technology Assessment; Vol. 28, No. 37. See the NIHR Funding and Awards website for further award information.

Leg ulcers are long-lasting wounds mostly caused by problems in blood flow in the veins, which are treated by applying bandages or stockings to create a 'compression' effect. However, compression should not be used in people with a condition called peripheral artery disease. To identify people with peripheral artery disease who should not receive compression therapy, health professionals perform a test called 'ankle­brachial pressure index', which involves taking blood pressure of the arms and ankles using a device called 'Doppler ultrasound'. The procedure is time-consuming and people with leg ulcers often find it uncomfortable. Automated devices have been proposed as a more acceptable option for assessing leg ulcers. However, we need to know whether these devices produce reliable results and represent good value for money for the National Health Service. We found 24 clinical studies that assessed 5 automated devices to measure ankle­brachial pressure index. The type of patients and clinical setting varied between studies. Two studies assessed people with leg ulcers and showed that the automated devices tended to give higher readings than standard Doppler and, therefore, may underestimate the presence of peripheral artery disease. Results of the 22 studies assessing people without leg ulcers showed that the automated devices could correctly identify people who did not have peripheral artery disease but were less precise in identifying people with peripheral artery disease. However, there was not enough evidence to confirm if these devices are reliable enough to be used in clinical practice. Compared to manual Doppler, the automated devices were less costly to deliver in clinical practice but had increased costs due to potentially inaccurate results. Our evaluation required many assumptions about how the devices would be used in practice, and there were no data on their impact on patient outcomes. Results are highly uncertain and should be interpreted cautiously. Given current evidence, it is unlikely that automated tests are a convenient option for the National Health Service.