Diagnostic Tools to Establish the Presence and Severity of Peripheral Arterial Disease in People With Diabetes

Study Overview
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Brief Summary
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In the UK there are over 7,000 leg amputations each year because of diabetes. The most important cause of this is poor circulation. The detection of poor circulation in patients with diabetes is difficult. A number of tests exist to detect poor circulation (known as peripheral arterial disease (PAD)). However, there is confusion as to which is the gold standard. The DM PAD study aims to determine the diagnostic performance of index tests (audible handheld Doppler, visual handheld Doppler, ankle brachial pressure index (ABPI), exercise ABPI and toe brachial pressure index (TBPI)) for the diagnosis of PAD in patients with diabetes as determined by a reference test (CTA or MRA).

Official Title
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Diagnostic Tools to Establish the Presence and Severity of Peripheral Arterial Disease in People With Diabetes

Conditions
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Diabetic Foot, Peripheral Arterial Disease, Diabetic Foot Ulcer, Peripheral Vascular Diseases, Peripheral Artery Disease, Critical Limb Ischemia, Critical Lower Limb Ischemia

Intervention / Treatment
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* Diagnostic Test: Toe Brachial Pressure Index (TBPI)
* Diagnostic Test: Ankle Brachial Pressure Index (ABPI)
* Diagnostic Test: Exercise Ankle Brachial Pressure Index (ABPI)
* Diagnostic Test: Audible handheld Doppler
* Diagnostic Test: Visual handheld Doppler
* Diagnostic Test: Podiatry Ankle Duplex scan (PAD-scan)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged ≥18 years Known history of diabetes Exclusion Criteria: PAD status known on imaging Known history of PAD intervention CTA and MRA contraindications- renal impairment, pregnancy, contrast medium hypersensitivity/allergy, non-compatible implants (MRA only). Unable to provide appropriate informed consent.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Participating Centre<br>To complete all index tests and reference scan | Diagnostic Test: Toe Brachial Pressure Index (TBPI)<br>* TBPI will be measured using the photoplethysmography (PPG) method, employing an infrared sensor placed on the hallux and index finger.<br>Diagnostic Test: Ankle Brachial Pressure Index (ABPI)<br>* A sphygmomanometer-cuff placed at the ankle and a handheld continuous wave Doppler device will be used to measure the systolic pressure of the dorsalis pedis and posterior tibial artery.<br>Diagnostic Test: Exercise Ankle Brachial Pressure Index (ABPI)<br>* A sphygmomanometer-cuff placed at the ankle and a handheld continuous wave Doppler device will be used to measure the systolic pressure of the dorsalis pedis and posterior tibial artery, following the participant completing 50 consecutive repetitions of active dorsiflexion whilst standing.<br>Diagnostic Test: Audible handheld Doppler<br>* Audible CW Doppler interrogation of the dorsalis pedis and posterior tibial artery.<br>Diagnostic Test: Visual handheld Doppler<br>* Visual CW interrogation of the dorsalis pedis and posterior tibial artery was performed using the handheld Huntleigh Digital Dopplex device.<br>Diagnostic Test: Podiatry Ankle Duplex scan (PAD-scan)<br>* Podiatry ankle duplex scan (PAD-scan) involves using an ultrasound machine to visualise the anterior and posterior tibial arteries at the ankle. To be used in 3 participating centers only.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic accuracy | Diagnostic accuracy of the PAD-scan and other bedside tests will be compared to the results of a Magnetic resonance angiograph (MRA) or Computed tomography angiography (CTA) (reference test). | 6 weeks; all index tests will be performed on the same day of presentation; reference scan performed within six weeks of the index tests. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Health economic outcome - cost of test | Cost of the test, including direct costs and amortisation of capital equipment and use of other healthcare resources for prevention and treatment of the disease over a time horizon of 5 years. | 1 hour: all index tests will be performed on the same day of presentation. | 
| Health economic outcome - Quality Adjusted Life Years | Quality Adjusted Life Years at 5 years | 1 hour: all index tests will be performed on the same day of presentation. | 
| Health economic outcome - cost effectiveness | Incremental cost-effectiveness ratio at 5 years. | 1 hour: all index tests will be performed on the same day of presentation. | 
| Specificity of index tests | Comparing index tests to reference tests. | 6 weeks | 
| Likelihood ratios of index tests | Comparing index tests to reference tests. | 6 weeks | 
| Predictive values of index tests | Comparing index tests to reference tests. | 6 weeks | 
| Diagnostic odds ratio of index tests | Comparing index tests to reference tests. | 6 weeks | 
| Patient acceptability | Patients will be asked to rate their experience of each index test on a Likert scale. | 1 hour: all index tests will be performed on the same day of presentation. | 
| Technical success | Inability to perform, refusal and discontinuation of tests will be documented | 6 weeks; all index tests will be performed on the same day of presentation; reference scan performed within six weeks of the index tests. | 
| Inter- and intra-rater reliability | Repeating of index tests by the same and by an alternative operator for the assessment intra- and inter-rater reliability, respectively (only performed in the first 100 volunteering patients). | 6 weeks; all index tests will be performed on the same day of presentation; reference scan performed within six weeks of the index tests. |