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Pre-operative Investigations in planning for Open Infra-inguinal revascularization for PAD

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Pre-operative Investigations in planning for Open Infra-inguinal revascularization for PAD

Mr Ahmed Elshiekh MBBCH MRCS, Mr Faisal Kahloon MRCS, Mr Asif Mahmood MB ChB MRCS MD FRCS (Gen Surg)

University Hospitals Coventry and Warwickshire NHS trust

 

Abstract:

Background:

Peripheral Arterial Disease (PAD) cause significant health and economic burden affecting about 9% of UK population.

Nice guidelines recommend performing Doppler US (DUS) as first line in all patients with PAD for whom re-vascularization is being considered. MRA should be performed if further imaging is needed before re-vascularization and CT angiography (CTA) is indicated only if MRA is not tolerated or contraindicated.

Some published studies showed superiority of contrast enhanced MRA over conventional diagnostic angiography.

On the basis of these guidelines diagnostic invasive lower limb angiography should not be routine practice because of risks and costs implications.

We performed a study to identify the adherence in our unit to these guidelines and the resulting impact on patient safety and service provision costs.

Methods:

Retrospective data collection for one year in a single large UK tertiary referral centre (University Hospital Coventry and Warwickshire). Fifty eight patients who underwent lower limb bypass surgery were included over a time period from June 2015 to June 2016.

Results:

75% of the patients (N: 44) had DUS as a first investigation, 29% (N: 17) had CTA or MRA as a second investigation and 39% (N: 23) of the patients had diagnostic angiography preoperatively with an overall complication rate (diagnostic and therapeutic angiography) of 12% including contrast leak, puncture site haematoma, dissection, retroperitoneal haemorrhage, blood transfusion and inability to tolerate the procedure.

The estimated costs of the angiographies during the one year period were £28,934 (£1,258 per patient).

Conclusion:

Significant percentage of patients going for lower limb bypass surgery are subject to unnecessary risk as they are having pre-operative diagnostic angiography with an overall increase in service costs. This is unjustified in the view of the current National guidelines and published literature.

 

Introduction:

 

Peripheral Arterial Disease (PAD) cause significant health and economic burden affecting about 9% of UK population. It is estimated that 20% of people aged over 60 years have some degree of peripheral arterial disease(1).

Diagnostic modalities commonly used vary from simple non-invasive modalities like Doppler ultrasound (DUS), CT angiography (CTA), Magnetic resonance angiography (MRA) up to invasive procedures as diagnostic angiography.

Although invasive diagnostic angiography has been historically considered as the gold standard for diagnosis on PAD, simple non invasive procedures have been to shown to have very high sensitivity and specificity. Simple Doppler ultrasound (DUS) was shown to have 78% sensitivity and 99% specificity for diagnosis of popliteal artery PAD with even better results in femoral artery with a 100% specificity and 95% sensitivity(2). CTA was shown to have sensitivity 96% and specificity 95%(3). MRA had a sensitivity of 93% and specificity of 94% and was even shown in more than one study to be superior to invasive angiography(4)(5).

Nice guidelines recommend performing Doppler US (DUS) as first line in all patients with PAD for whom re-vascularization is being considered. MRA should be performed if further imaging is needed before re-vascularization and CT angiography (CTA) is indicated only if MRA is not tolerated or contraindicated(6).On the basis of these guidelines diagnostic invasive lower limb angiography should not be routine practice because of risks and costs implications.

Average costs of angiography ranges from £1,135 up to £1,995 according to data published in 2016/2017 by NHS England with costs of DUS, CTA and MRA being £56, £120 and £211 respectively(7).

We performed a study to identify the adherence in our unit which is a big university hospital and tertiary referral centre in the UK to these guidelines and the resulting impact on patient safety and service provision costs.

 

Patients & Methods:

 

Retrospective data collection from patients records in a single large UK tertiary referral centre (University Hospital Coventry and Warwickshire) over a one-year time period from June 2015 to June 2016. All Patients who underwent lower limb bypass surgery were included except those who had an extra-anatomical bypass.

Hospital research and development department approval was acquired.

 

Results:

 

Fifty-eight patients who underwent lower limb bypass surgery from June 2015 to June 2016 were included.

75% of these patients (N: 44) had DUS as a first investigation, 29% (N: 17) had CTA or MRA as a second investigation.

Of the patients included in our study 84% underwent angiography with 46% of them having diagnostic angiography and only 34% having therapeutic angiography (N:49, N diagnostic:23, N therapeutic:17). Overall 39 % of all patients included in our study had diagnostic angiography (N: 23/58).

Table one shows the numbers of patients who underwent each investigation and the order of the investigation in relation to other investigations done for the same patients.

 

Table 1 :The numbers of patients who underwent each investigation and the order of the investigation in relation to other investigations done for the same patients.

Inv Order

US

MRI

CT

Angiography

1st

44 (75 %)

5 (8.6 %)

7 (12 %)

2 (3%)

2nd

2 (3.8%)

10 (19 % )

7 (13 %)

33 (63 %)

3rd

4 (22 %)

0

0

14 (77% )

 

The complications rate of angiography (diagnostic and therapeutic angiography) for patients included in our study was 12%. The complications that occurred during our study included contrast leak, puncture site haematoma, dissection, retroperitoneal haemorrhage, blood transfusion and inability to tolerate the procedure. Table two shows the complications.

 

Table 2 The complications (* complications happening in the same patient)

Contrast leak

Haematoma

Procedure not tolearted

Arterial perforation, subintimal dissection

Retroperitoneal Haematoma ,hypotension and blood transfusion

1

2

1

1*

1*

 

The estimated costs of the angiographies during the one-year period were £28,934 (£1,258 per patient).

 

Discussion:

 

Although lower limb angiography is still being though of by many as the gold standard for preoperative evaluation for lower limb ischaemia patients, less invasive modalities are not inferior and maybe even superior to it without carring the same risks inherent to its nature as an invasive procedure. Lower limb angiography complications maye be secondary to the vascular access required (e.g. bleeding, infection, atheroembolism, dissection, vessel disruption or perforation, hematoma, pseudoaneurysm, arteriovenous fistula) or the utilization of contrast material. The complications rate in our study were 12%. This was for both diagnostic and therapeutic procedures done. In literature the complications rate for diagnostic angiography alone was lower than this at 1.9 to 2.9%(8). This maybe due to the fact that we did not include large number of patients.

 

The costs of the diagnostic angiographies in our unit over a one-year period were estimated to be £28,934. However, this does not present the real number because it did not include the price for medical staff hours used and blocking of a day case bed. Furthermore, if a complication happens the patient will need to be admitted to the hospital with a rise in overall cost. Thus the real cost saving that can be done by avoiding diagnostic angiographies would be much higher than this figure.

 

Conclusion:

 

Significant percentage of patients going for lower limb bypass surgery are subject to unnecessary risk as they are having pre-operative diagnostic angiography with an overall increase in service costs. This is unjustified in the view of the current National guidelines and published literature.

 Re-aduit:

Intervention

Quality improvement meeting (21/10/2016) organised between Vascular department and radiology with attendance of different team members (Consultanats-Registrars-SHO-FY1-secretaries ) in which the issue was discussed 

Results

Audit point

Target

Cycle 1

Cycle 2

DUS should be 1st investigation of choice

100%

75%

80%

Diagnostic angio should not be done for this group of patients .

100%

 

61%

90%

CTA/MRA should be done as second choice in patients needing further investigations after DUS

100%

38%

75%

References:

 

1.        Marrett E, DiBonaventura M, Zhang Q. Burden of peripheral arterial disease in Europe and the United States: a patient survey. Health Qual Life Outcomes [Internet]. 2013 [cited 2017 Apr 9];11(1):175. Available from: http://hqlo.biomedcentral.com/articles/10.1186/1477-7525-11-175

2.        Moneta GL, Yeager RA, Lee RW, Porter JM. Noninvasive localization of arterial occlusive disease: a comparison of segmental Doppler pressures and arterial duplex mapping. J Vasc Surg [Internet]. 1993 Mar [cited 2017 Apr 9];17(3):578–82. Available from: http://www.ncbi.nlm.nih.gov/pubmed/8445755

3.        Jens S, Koelemay MJW, Reekers JA, Bipat S. Diagnostic performance of computed tomography angiography and contrast-enhanced magnetic resonance angiography in patients with critical limb ischaemia and intermittent claudication: systematic review and meta-analysis. Eur Radiol [Internet]. 2013 Nov 26 [cited 2017 Apr 9];23(11):3104–14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23801421

4.        Leiner T, Kessels AGH, Schurink GW, Kitslaar PJEHM, de Haan MW, Tordoir JHM, et al. Comparison of contrast-enhanced magnetic resonance angiography and digital subtraction angiography in patients with chronic critical ischemia and tissue loss. Invest Radiol [Internet]. 2004 Jul [cited 2017 Apr 9];39(7):435–44. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15194915

5.        Dorweiler B, Neufang A, Kreitner K-F, Schmiedt W, Oelert H. Magnetic resonance angiography unmasks reliable target vessels for pedal bypass grafting in patients with diabetes mellitus. J Vasc Surg [Internet]. 2002 [cited 2017 Apr 9];35(4):766–72. Available from: http://www.sciencedirect.com/science/article/pii/S0741521402383393

6.        Peripheral arterial disease: diagnosis and management  | Guidance and guidelines | NICE. [cited 2017 Apr 9]; Available from: https://www.nice.org.uk/guidance/cg147

7.        NHS England » National Tariff Payment System 2016/17 [Internet]. [cited 2017 Apr 9]. Available from: https://www.england.nhs.uk/resources/pay-syst/tariff-consultation-notice/

8.        Balduf LM, Langsfeld M, Marek JM, Tullis MJ, Kasirajan K, Matteson B. Complication Rates of Diagnostic Angiography Performed by Vascular Surgeons. Vasc Endovascular Surg [Internet]. 2002 Nov 1 [cited 2017 Apr 9];36(6):439–45. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12476233

 

 

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