Diagnostic Test Accuracy Protocol

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Ankle brachial index for the diagnosis of symptomatic peripheral arterial disease

  1. Fay Crawford1,*,
  2. Francesca M Chappell2,
  3. Karen Welch3,
  4. Alina Andras1,
  5. Julie Brittenden4

Editorial Group: Cochrane Peripheral Vascular Diseases Group

Published Online: 9 AUG 2013

DOI: 10.1002/14651858.CD010680


How to Cite

Crawford F, Chappell FM, Welch K, Andras A, Brittenden J. Ankle brachial index for the diagnosis of symptomatic peripheral arterial disease (Protocol). Cochrane Database of Systematic Reviews 2013, Issue 8. Art. No.: CD010680. DOI: 10.1002/14651858.CD010680.

Author Information

  1. 1

    Freeman Hospital, Department of Vascular Surgery, Newcastle upon Tyne, UK

  2. 2

    University of Edinburgh, Division of Clinical Neurosciences, Edinburgh, UK

  3. 3

    University of Edinburgh, Public Health Sciences, Edinburgh, UK

  4. 4

    Aberdeen Royal Infirmary, University of Aberdeen, c/o Vascular Unit - Ward 36, Aberdeen, Scotland, UK

*Fay Crawford, Department of Vascular Surgery, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, High Heaton, Newcastle upon Tyne, NE7 7DN, UK. fay.crawford@nuth.nhs.uk. fay.crawford@ed.ac.uk.

Publication History

  1. Publication Status: New
  2. Published Online: 9 AUG 2013

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Background

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support

Peripheral arterial disease (PAD) is common, with a prevalence of both symptomatic and asymptomatic disease estimated at 13% in the over 50 age group (Hirsch 2001). Symptomatic PAD affects about 5% of Western populations between the age of 55 and 74 years (Khan 2007). The deposition of atheromatous plaques (fatty deposits) and superadded thrombus (additional blood clot) results in arterial stenosis (narrowing) and occlusion. In the lower limb this leads to inadequate blood flow to the muscles during exercise causing muscle pain that is relieved by rest. This is known as intermittent claudication (IC). Intermittent claudication is the most common symptom of PAD, though in severe cases critical limb ischaemia (with symptoms of rest pain, ulceration, and gangrene) may develop, which, if untreated, can lead to lower limb amputation (Hooi 2007; Twine 2009). PAD is also associated with an increased risk of cardiovascular disease and stroke (Heald 2006).

The ankle brachial index (ABI) - or ankle brachial pressure index (ABPI) as it is also known - is used to diagnose PAD. A sphygmomanometer (device for measuring blood pressure) with an inflatable cuff is used to measure the systolic blood pressure at the upper arm or the ankle. This equipment can be either manual or digital to achieve readings. Manual equipment can use mercury or be aneroid (mechanical) in nature and require a stethoscope or a doppler flow auscultation. Digital equipment use oscillometric measurements and electronic calculation.

The ABI is widely used to assess PAD by a wide variety of healthcare professionals including specialist nurses, physicians, surgeons, and podiatrists working in secondary care settings. Division of the recorded blood pressure at the ankle with that recorded at the arm produces a ratio. Ratios of 0.90 to 1.30 are considered to be normal for adults, while ratios of less than 0.8 are indicative of arterial stenosis, and ratios between 0.75 to 0.5 are associated with severe ischaemia, poor healing and, in some cases gangrene (Bhasin 2007; MacLeod-Roberts 1995).

In secondary care a variety of imaging tests may be used to diagnose PAD; duplex ultrasound (DUS) allows the assessment of blood flow in the arteries, it is non-invasive and highly dependent on the experience of the radiologist to achieve useful images. Different types of angiography can also be used to image the blood vessels, namely; computerised tomography angiogram (CTA), magnetic resonance angiogram (MRA) and catheter angiogram.

The clinical severity of PAD is usually described using the Rutherford Classification Index (Rutherford 1997), or the Fontaine classification system (Fontaine 1954). In the former, patients are classified into one of four to six categories according to the degree of sensory loss, muscle weakness and arterial and venous measurements in acute and chronic PAD. These classified states which range from viable to threatened marginal, threatened immediate, and irreversible for acute PAD, and from asymptomatic, to mild, moderate or severe claudication, ischaemic rest pain and minor or major tissue loss for chronic disease, have different prognoses or outcomes (Rutherford 1997). The Fontaine classification index describes four disease states from no symptoms (stage I) to tissue necrosis, death and gangrene (stage 4) (Fontaine 1954).

People with IC may be prescribed naftidrofuryl oxalate and offered supervised exercise therapy, but those with incapacitating disease and significantly impaired quality of life may require some form of surgical arterial revascularisation (Bendermacher 2006; Cassar 2003; Chang 2011; de Backer 2012; NICE 2012; Rutherford 1997; Watson 2008).

As well as identifying people with PAD, the ABI can be used to predict the risk of cardiovascular events (Ankle Brachial Index Collaboration 2008; SIGN 2007). People with symptomatic PAD are known to have an increased risk of cardiovascular mortality, and subsequently receive treatment to manage their cardiac risk (Bhasin 2007).

As the ABI test is non-invasive, inexpensive and in widespread clinical use, a systematic review of its diagnostic accuracy is highly relevant to routine clinical practice.

 

Target condition being diagnosed

Presence or absence of peripheral arterial disease.

 

Index test(s)

Ankle brachial index (ABI) is used to diagnose peripheral arterial disease (PAD). It is calculated by dividing the systolic pressure measured in the arteries at the ankle (dorsalis pedis and posterior tibial arteries) by the systolic blood pressure at the arm (brachial artery).

There are several ways to calculate an ankle brachial ratio. UK clinical guidelines recommend that the patient is rested in a supine position. The blood pressure is taken using a sphygmomanometer with an appropriately-sized cuff at the brachial artery and the posterior tibial, dorsalis pedis, and, where possible, peroneal arteries. The audible systolic pressure is detected with a doppler scanning probe (McDermott 2000; NICE 2012).

For each leg the ABI is calculated by dividing the highest ankle pressure by the highest pressure reading taken from the arm (McDermott 2000). The ABI values have been classed as follows (MacLeod-Roberts 1995):

Normal values range: 0.90 to 1.30;
Mild disease range: 0.7 to 0.9;
Moderate disease range: 0.41 to 0.69;
Severe disease (critical limb ischaemia): less than, or equal to (≤) 0.4.

In this review, we shall use the threshold of less than 0.90 to distinguish between test positive (< 0.90) and test negative (≥ 0.90) results. This threshold is commonly used in clinical practice and is cited in current guidelines (NICE 2012).

The position of the patient at the time the blood pressure is taken is important: for each inch that the ankle is positioned below the heart there is a 1 mmHg increase in systolic ankle blood pressure (MacLeod-Roberts 1995).

False negatives are known to occur in people who have calcification of the ankle artery wall, which creates incompressibility and an artificially high reading. This may occur in some patients with diabetes (Bhasin 2007; MacLeod-Roberts 1995).

There are a number of automated blood pressure machines all of which will be eligible for inclusion in the review.

 

Clinical pathway

There are several clinical pathways for people to be diagnosed with mild to moderate PAD using the ABI: during routine diabetic foot checks in primary care, community health settings or hospital settings. Similarly, members of the general population who report symptoms such as pain on walking may be diagnosed by means of the ABI. People may also be identified in accident and emergency departments, having presented with an acute episode of intermittent claudication and referred to either primary care or other secondary, hospital-based departments such as vascular surgery and vascular laboratories for treatment or further assessment.

 

Role of index test(s)

As outlined above, this review will include studies that evaluate the diagnostic test accuracy of the ABI in a variety of healthcare settings, with different patient groups by a range of healthcare professionals.

 

Alternative test(s)

The range of uses of the ABI in clinical practice is diverse and there are no standard alternative tests to consider.

 

Rationale

The success of management strategies for PAD depend upon the quality of the diagnostic process, which involves a careful assessment of the underlying pathology using diagnostic tests that possess a high level of accuracy, to allow the detection and measurement of an arterial stenosis and its distribution in the blood vessels.

 

Objectives

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support

To estimate the diagnostic accuracy of the ankle brachial index (ABI) - also known as the ankle brachial pressure index (ABPI) - for the diagnosis of peripheral arterial disease in people who experience pain on walking that is alleviated by rest (intermittent claudication).

 

Secondary objectives

We will also investigate the effect of sources of heterogeneity on diagnostic accuracy; specifically, the study setting, previous tests, types of equipment used, type of reference standard, different groups of patients (people with type I or type II diabetes and suspected aortic iliac disease), and the duration of symptoms by including them as covariates in the meta-analysis, if there are sufficient studies with relevant data. Other potential sources of heterogeneity will be examined graphically for signs that they are a cause of heterogeneity.

 

Methods

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support
 

Criteria for considering studies for this review

 

Types of studies

We will include cross-sectional studies of ABI where duplex ultrasound is used as the reference standard. Cross-sectional or diagnostic test accuracy (DTA) cohort studies including both prospective and retrospective studies will be included in the review. Patients should be reported as being recruited consecutively or as a random sample. Only studies that report that all patients received, a reference standard, and present 2 x 2 data will be eligible for inclusion.

 

Participants

Adults with leg pain that is worse on walking and alleviated by rest, who are tested in primary and secondary care settings (hospital outpatients) and who are classified as category 1, 2, or 3 based on the Rutherford index (Rutherford 1997), or stage II based on the Fontaine classification system (Fontaine 1954). Patients with either type I or type II diabetes and with other pathologies suspected of affecting the arteries (e.g. aortic iliac disease) will also be included. Patients with pain at rest (more severe disease) and those who are free of symptoms will be excluded from the review.

 

Index tests

Ankle brachial index (ABI), also called the ankle brachial pressure index (ABPI). Data collected using sphygmomanometers (both manual and aneroid) as well as digital equipment using manual or automatic inflation will be included in the review.

 

Target conditions

Peripheral arterial disease.

 

Reference standards

We will use duplex ultrasound as the reference standard test. This non-invasive test is used for people who are classified at Rutherford index 1, 2 or 3, or Fontaine category II.

 

Search methods for identification of studies

There will not be any restrictions in terms of date, language of publication or publication status of studies. No diagnostic methodology search filters will be employed.

 

Electronic searches

The Trials Search Co-ordinator of the Cochrane Peripheral Vascular Diseases Group will carry out electronic searches of;

  • MEDLINE (OvidSP)
  • EMBASE (OvidSP)

using the search strategies shown in Appendix 1 and Appendix 2.

In addition similar search strategies will be designed for;

  • CINAHL via EBSCO
  • LILACS (Bireme)
  • DARE (Database of Abstracts of Reviews of Effects) and the Health Technology Assessment Database (HTA) in The Cochrane Library
  • ISI's Conference Proceedings Citation Index-Science
  • British Library Zetoc conference search

using search terms appropriate for each of these databases and based on the MEDLINE search terms.

We will also search MEDION (www.mediondatabase.nl/) using the 'Systematic Reviews of Diagnostic Studies' search filter.

We will request a search of the Cochrane Register of Diagnostic Test Accuracy Studies for further relevant studies.

 

Searching other resources

We will also review the bibliographies of review articles identified by the searches for potentially relevant studies.

 

Data collection and analysis

 

Selection of studies

One reviewer (FC) will screen the titles and abstracts retrieved by the electronic searches and a second reviewer (AA) will check a random sample of 10% of the studies. Full papers will be obtained for potentially eligible studies including those identified by non-electronic means. Two review authors (FC, AA) will independently apply the exclusion criteria to the full papers and resolve any disagreements by discussion. We will use a flow diagram to show the results of the decision-making process.

 

Data extraction and management

Data extraction will be replicated by two review authors (FC, AA) independently using a standard form, which will include an assessment of study quality. The review authors will corroborate their data extraction and quality assessment decisions and disagreements will be resolved by discussion. The review authors will extract patient-level data to populate 2 x 2 contingency tables (true positives (TP) true negatives (TN), false positives (FP) and false negatives (FN)), as reported. Details of test threshold(s) used for the interpretation of results will be extracted.

We will collect data on mortality, adverse events, the nature of the equipment used (manual or automated) and the number of technical failures.

 

Assessment of methodological quality

After a pilot phase involving two reviewers working independently, we will use the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) (Whiting 2011) to develop a quality assessment tool, incorporating the review question, a flow diagram for the study and an assessment of risk of bias and applicability judgements. Review-specific signalling questions, appropriate items concerning the applicability of primary studies relative to the review, together with guidance about rating can be found in Appendix 3. We will resolve disagreements by discussion.

 

Statistical analysis and data synthesis

We will present and use the 2 x 2 contingency tables, based on patient-level data rather than limbs, to estimate sensitivity and specificity for each study. If the data are adequate, we will perform a bivariate random-effects meta-analysis of sensitivity and specificity. These estimates will be used to create receiver operating characteristic (ROC) and forest plots. As an ABI of less than 0.90 is the accepted threshold used in clinical practice, we will restrict the meta-analysis to studies that used this threshold, so that our estimates of sensitivity and specificity are derived directly from that threshold. Items to be investigated for heterogeneity will be added as covariates to the bivariate model. If the data are not amenable to a bivariate meta-analysis, we shall consider conducting univariate meta-analyses for both sensitivity and specificity (Harbord 2007).

All analyses will be performed in R 7.1 (cran.r-project.org) and SAS 9.3 (www.sas.com).

 

Investigations of heterogeneity

Our investigations into the effect of sources of heterogeneity on diagnostic accuracy will focus on patient groups (type I and type II diabetes, and suspected aortic iliac disease), the duration of symptoms, previous tests, and types of equipment (automatic or manual) by including them as covariates in the meta-analyses. Other potential sources of heterogeneity will be examined graphically for signs that they are a cause of heterogeneity. Estimates will be grouped in plots according to items that are considered to be potential sources of heterogeneity as detailed above. These will be presented in forest and ROC plots for visual assessment of heterogeneity.

If there are sufficient studies, heterogeneity will be investigated by adding items as covariates to the meta analysis model. This model may be the bivariate or univariate analysis, depending on the results of the main analysis.

In recognition of the likelihood of having too few studies to perform meta-regression with all the items listed as potential sources of heterogeneity, we shall limit ourselves to visual inspection of ROC and forest plots. We also recognise that some items are investigated better with individual patient data, as they are patient- rather than study-specific - for example, duration of symptoms - and so we will interpret any results cautiously.

 

Sensitivity analyses

We intend to conduct several sensitivity analyses to compare the diagnostic accuracy of ABI in those with and without diabetes, with and without coronary heart disease, smokers versus non smokers and manual versus automated methods of measurement of the ABI.

 

Assessment of reporting bias

Methods for dealing with publication bias in reviews of diagnostic accuracy studies are relatively underdeveloped. Consequently, we shall interpret our results cautiously, and with an awareness of the likelihood of publication bias, rather than use funnel plots, which can be challenging to interpret in this context. We shall consider using a funnel plot of the log of the diagnostic odds ratio (lnDOR), providing there is low heterogeneity in the lnDOR (Deeks 2005).

 

Acknowledgements

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support

This review forms part of a National Institute of Health Research (NIHR) Cochrane programme grant.

 

Appendices

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support
 

Appendix 1. MEDLINE search strategy

1. Ankle Brachial Index/

2. Oscillometry/mt [Methods]

3. Blood Pressure Determination/

4. Laser-Doppler Flowmetry/

5. oscillometr$.ti,ab.

6. (doppler adj2 (ultrasound or flow$ or method or device)).ti,ab.

7. ABI.ti,ab.

8. ABPI.ti,ab.

9. AAI.ti,ab.

10. (ankle adj4 index).ti,ab.

11. (arm adj4 index).ti,ab.

12. (brachial adj4 (index or pressure)).ti,ab.

13. (systolic adj5 ratio).ti,ab.

14. (pressure adj5 ratio).ti,ab.

15. (BP adj5 ratio).ti,ab.

16. (four and limbs and pressure).ti,ab.

17. or/1-16

18. (anterior tibial or dorsalis pedis or posterior tibial).ti,ab.

19. (ankle or arm or elbow or calf).ti,ab.

20. (lower and upper and (extremit$ or limb)).ti,ab.

21. or/18-20

22. (systolic or pressure).ti,ab.

23. 21 and 22

24. 17 or 23

25. exp Peripheral Vascular Diseases/di [Diagnosis]

26. Arterial Occlusive Diseases/di [Diagnosis]

27. exp Arteriosclerosis/di [Diagnosis]

28. exp Atherosclerosis/di [Diagnosis]

29. exp Peripheral Arterial Disease/di [Diagnosis]

30. Intermittent Claudication/di [Diagnosis]

31. (atherosclero* or arteriosclero* or PVD or PAOD or PAD).ti,ab.

32. (arter$ adj4 ($occlus$ or steno$ or obstuct$ or lesio$ or block$ or obliter$)).ti,ab.

33. (vascular adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

34. (vein* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

35. (veno* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

36. (peripher* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

37. (peripheral adj3 dis*).ti,ab.

38. arteriopathic.ti,ab.

39. (claudic* or hinken* or IC).ti,ab.

40. CLI.ti,ab.

41. dysvascular*.ti,ab.

42. (leg adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

43. (limb adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

44. (lower adj3 extrem* adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

45. or/25-44

46. 24 and 45

 

Appendix 2. EMBASE search strategy

1. ankle brachial index/

2. oscillometry/

3. blood pressure measurement/

4. laser Doppler flowmetry/

5. oscillometr$.ti,ab.

6. (doppler adj2 (ultrasound or flow$ or method or device)).ti,ab.

7. ABI.ti,ab.

8. ABPI.ti,ab.

9. AAI.ti,ab.

10. (ankle adj4 index).ti,ab.

11. (arm adj4 index).ti,ab.

12. (brachial adj4 (index or pressure)).ti,ab.

13. (systolic adj5 ratio).ti,ab.

14. (pressure adj5 ratio).ti,ab.

15. (BP adj5 ratio).ti,ab.

16. (four and limbs and pressure).ti,ab.

17. or/1-16

18. (anterior tibial or dorsalis pedis or posterior tibial).ti,ab.

19. (ankle or arm or elbow or calf).ti,ab.

20. (lower and upper and (extremit$ or limb)).ti,ab.

21. or/18-20

22. (systolic or pressure).ti,ab.

23. 21 and 22

24. 17 or 23

25. peripheral vascular disease/di [Diagnosis]

26. artery disease/di [Diagnosis]

27. arteriolosclerosis/di [Diagnosis]

28. arteriosclerosis/di [Diagnosis]

29. atherosclerosis/di [Diagnosis]

30. atherosclerotic plaque/di [Diagnosis]

31. peripheral occlusive artery disease/di [Diagnosis]

32. artery occlusion/di [Diagnosis]

33. intermittent claudication/di [Diagnosis]

34. (atherosclero* or arteriosclero* or PVD or PAOD or PAD).ti,ab.

35. (arter$ adj4 ($occlus$ or steno$ or obstuct$ or lesio$ or block$ or obliter$)).ti,ab.

36. (vascular adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

37. (vein* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

38. (veno* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

39. (peripher* adj4 (occlus* or steno* or obstuct* or lesio* or block* or obliter*)).ti,ab.

40. (peripheral adj3 dis*).ti,ab.

41. arteriopathic.ti,ab.

42. (claudic* or hinken* or IC).ti,ab.

43. CLI.ti,ab.

44. dysvascular*.ti,ab.

45. (leg adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

46. (limb adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

47. (lower adj3 extrem* adj4 (obstruct* or occlus* or steno* or block* or obliter*)).ti,ab.

48. or/25-47

49. 24 and 48 

 

Appendix 3. Quality Assessment Checklist (QUADAS-2)


Domains, signalling questions (SQ) and applicabilityRating criteria

Domain 1: Patient selection 

A. Risk of biasDescribe the methods of patient selection given in the report:

SQ 1:

Was a consecutive or random sample of patients enrolled?
Yes: it is reported that a consecutive or a random sample was included

Unclear: the precise method of sampling is not reported

SQ 2:

Did the study avoid inappropriate exclusions?
Yes: the study included all symptomatic out-patients (in primary or secondary care) without previous ABI test results

No: the study included patients who had received an ABI test before, or were asymptomatic

Unclear: the ABI test history of the patients in the study was not reported

B. Concerns regarding applicabilityGive the paper's description of the inclusion/exclusion criteria: including setting, prior tests, symptoms here

Domain 2: Index test 

A. Risk of biasGive the paper's description of the index test and how it was conducted and interpreted, including the background of the person who carried out the test

SQ 1:

Were index test results interpreted without knowledge of the results of the reference standard?
Yes: it is stated that the index tests were interpreted in a blind manner i.e. without knowledge of the results of the reference standard, or the index test was always performed and interpreted before the reference standard

No: the results of the reference standard were known to the reader of the index test

Unclear: it is not reported whether the index test was conducted without knowledge of the results of the index test, or whether the index test was completed before the reference standard

SQ 2:

If a threshold was used was it pre-specified?
Yes: value for an abnormal test result is < 0.90 and this is clearly stated in the methods section or elsewhere in the report

No: values for a normal or abnormal test results are not reported (pre-specified)

Unclear: it is not clear at what point in time values for normal and abnormal test results were decided

SQ 3:

Was the person conducting the test (measuring the ABI) trained to do so?
Yes: it is stated that the person conducting the conducting the test was trained in ABI measurement

No: it is clearly reported that the person conducting the test was untrained in ABI measurement

Unclear: the expertise and background of the individuals conducting the index test is unclear

B. Concerns regarding applicability?High: the index test was conducted using hand-held dopplers as opposed to a stethoscope or other equipment not widely available

Low: the index test was not conducted using hand-held dopplers and the equipment was standard (as outlined in the protocol)

Unclear: information about the equipment used to conduct the test is not presented

Domain 3: Reference standard 

A. Risk of biasGive the reported definition of the reference standard and how it was conducted and interpreted

SQ 1:

Is the reference standard likely to correctly classify the target condition?
Yes: it is reported that duplex ultrasound test results were interpreted by trained operatives

No: it is reported that the duplex ultrasound test results were not interpreted by trained operatives

Unclear: it is not clear whether those individuals who interpreted the duplex ultrasound test results were trained

SQ 2:

Were the reference standard test results interpreted without knowledge of the index test results?
Yes: the person classifying the reference standard test results was unaware of the ABI test results

No: the person classifying the reference standard test results was aware of the ABI test results

Unclear: not reported

SQ 3:

Was the person conducting the reference standard test (duplex ultrasound) trained?
Yes: it is stated that the person conducting the reference standard test was trained in the interpretation of duplex ultrasound
No: it is clear the person conducting the reference standard test was not trained in the interpretation of duplex ultrasound

Unclear: the expertise and background of the reference standard test readers is unclear

Domain 4: Flow and timing  

A. Risk of biasDescribe the reasons why any patients recruited into the study did not contribute to the 2 x 2 table (i.e. patients who did not undergo the reference standard and/or the index test) referring to the flow diagram

Give the time interval between the ABI and the reference standard tests

SQ 1:

Was there an appropriate interval between the index test and the reference standard?
Yes: the index and reference standard tests were all conducted within 2 weeks of each other

No: some of the reference standard test results were not conducted within 2 weeks of each other

Unclear: no information about the relative timing of the tests is provided

SQ 2:

Did all the patients receive the same reference standard?
Yes: a complete set of reference standard test results is available for all study patients

No: the same reference standard test results are not available for all patients

Unclear: insufficient information is available to make a judgement about the availability of reference standard

SQ 3:

Were all patients included in the final analysis?
Yes: all patients enrolled contributed to the 2 x 2 table

No: not all patients enrolled contributed to the 2 x 2 table

Unclear: it is not clear whether there were patients recruited, but not included in the study report of 2 x 2 table



 

 

Contributions of authors

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support

The whole review team have contributed to the development of the protocol. KW developed the search strategy. FC and AA will apply the eligibility criteria, extract data from studies and enter data into RevMan. FMC will conduct the analysis. JB will provide expert clinical advice. All authors will contribute to the final report of the review.

 

Declarations of interest

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support

FC: none known
FMC: none known
KW: none known
AA: none known
JB: none known

This review forms part of a National Institute of Health Research (NIHR) Cochrane programme grant. The review is being conducted independently of our funders, the NIHR. The NIHR have no input on the conduct or results of the review.

 

Sources of support

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
  9. Sources of support
 

Internal sources

  • No sources of support supplied

 

External sources

  • Chief Scientist Office, Scottish Government Health Directorates, The Scottish Government, UK.
    The PVD Group editorial base is supported by the Chief Scientist Office.
  • National Institute of Health Research, UK.
    This review forms part of a programme of high priority systematic reviews in the diagnosis and treatment of peripheral vascular disease funded by the National Institute of Health Research (NIHR) in a partnership between the Cochrane PVD Group and the NHS in England.

References

Additional references

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Acknowledgements
  7. Appendices
  8. Contributions of authors
  9. Declarations of interest
  10. Sources of support
  11. Additional references
Ankle Brachial Index Collaboration 2008
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Bendermacher 2006
Bhasin 2007
Cassar 2003
  • Cassar K, Bachoo P, Brittenden J. The effect of peripheral percutaneous transluminal angioplasty on quality of life in patients with intermittent claudication. European Journal of Vascular and Endovascular Surgery 2003;26(2):130-6.
Chang 2011
  • Chang ZN, Lui ZY. Subintimal angioplasty for chronic lower limb arterial occlusion. Cochrane Database of Systematic Reviews 2011, Issue 11. [DOI: 10.1002/14651858.CD009418]
de Backer 2012
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Deeks 2005
  • Deeks JJ, Macaskill P, Irwig L. The performance of tests of publication bias and other sample size effects in systematic reviews of diagnostic test accuracy was assessed. Journal of Clinical Epidemiology 2005;58(9):882-93.
Fontaine 1954
  • Fontaine R, Kim M, Kieny R. Surgical treatment of peripheral circulation disorders [Die Chirurgische Behandlung Der Peripheren Durch-blutungsstörungen]. Helvetica Chirurgica Acta 1954;21(5-6):499-533.
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