Compression therapy is proven to be a safe and effective treatment for lower leg conditions such as lymphatic insufficiency and venous hypertension. In 2018, approximatively 250 million people across the globe were treated with compression therapy (Fortune Business Insights, 2020).
The most common method of arterial assessment is the calculation of a patient's ankle-brachial pressure index (ABPI) and the measurement and recording of this is embedded within many policies and best practice statements. ABPI compares the arterial flow of the brachial artery in the arm and the dorsalis pedis artery and/or posterior tibial artery in the leg, providing a ratio determining the presence and severity of peripheral artery disease (PAD), therefore assessing an individual's suitability for compression therapy alongside an in-depth holistic leg assessment (Song et al, 2019).
Lower limb disorders and leg ulcers are some of the most common conditions treated in the UK by the NHS (Heatley et al, 2020). It is estimated that 1.5% of the adult population are living with an active leg ulcer and around 80% of these lesions are classed as a venous leg ulcers (VLUs). Managing these patients is thought to cost the NHS around £2 billion each year (Todd, 2019; Heatley et al, 2020; Manchester University NHS Foundation Trust 2020).
With nursing visits being the largest cost factor, the need to improve accuracy of diagnosis to ensure effective, evidence-based treatments are implemented is paramount to help alleviate the financial burden (Phillips et al, 2020). The costs to the NHS of managing these patients in the UK has been estimated to be in a range of £698 to £3998 per patient for a healed VLU and between £1719 and £5976 per patient for unhealed VLU (Guest et al, 2016). Trevethan (2018) has suggested that the health problems and rising costs associated with the management of patients with VLUs are issues for not only UK but also global healthcare systems.
Aim
The aim of this review is to critically review and analyse findings from contemporary literature to evaluate the effectiveness of the ABPI as a screening tool to assess patients' suitability for the safe application of strong compression therapy.
Methods
A structured literature review was carried out using a narrative approach to review a variety of documents including research, practice and policy literature. This format was chosen to allow for a systematic review of both the theoretical and contextual aspects of the subject topic (Da Costa et al, 2020).
Search strategy
A systematic approach included searches of five electronic databases between September 2021 and November 2021. These were CINAHL, Summon, MEDLINE, the Cochrane Library and PubMed.
Terms used were:
- Ankle brachial pressure index (ABPI)
- Compression therapy
- Lower limb
- Patient safety.
Search inclusion criteria were limited to publications written in English, relevant to ABPI assessment and empirical research. Exclusion criteria included literature reviews, expert opinions, editorials and non-English papers. No restrictions were placed on the country of publication as long as the paper was written in English. Only published research after September 2016 was included in the search, as that was when the last Cochrane review on the use of ABPI in diagnosis of lower limb PAD was published (Crawford et al, 2016).
The refinement of the search results was documented using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flow chart (Page et al, 2021) (Figure 1).
Critical appraisal of literature
The critical appraisal tool selected for the literature review was the Critical Appraisal Skills Programme (CASP) (2021) tool. The CASP tool is a systematic and structured assessment method, comprising several questions to undertake an in-depth analysis of a piece of research. It is recommended for the novice researcher, endorsed by the Cochrane Qualitative and Implementation Methods Group and is commonly used when appraising health-related qualitative evidence (Long et al, 2020; CASP, 2021). The CASP (2021) tool was employed to appraise the chosen studies. This process ensured quality assurance, with each study considered to be of suitable quality and appropriate to be included within the literature review (Long et al, 2020). Each of the studies chosen had a clear research aim, methodology and understanding of the findings (Table 1).
Table 1. Summary of study findings
| Author(s), date, country | Design | Method | Sample size | Key themes identified | Key findings |
|---|---|---|---|---|---|
| Yap Kannan et al (2016) UK | Quantitative analysis | Survey questionnaire | Ninety-one questionnaires completed out of 118 offered All GPs |
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| Scott et al (2019) UK | Qualitative analysis | Semistructured interviews and observations | Thirteen nurses (practice nurses and research nurses) were observed with 51 patients |
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| Weller et al (2020) Australia | Qualitative analysis | Face-to-face, semistructured interviews and telephone interviews | Thirty-five primary care clinicians: 15 GPs, 20 practice nurses |
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| Ding and Lloyd (2021) New Zealand | Qualitative analysis | Face-to-face, semistructured interviews | Thirteen health professionals: nine GPs (primary care); two vascular surgeons (secondary care); two allied health professionals (secondary care) |
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ABPI: ankle–brachial pressure index; PAD: peripheral artery disease; VLU: venous leg ulcer
Results
Four studies were identified for inclusion (Yap Kannan et al, 2016; Scott et al, 2019; Weller et al, 2020; Ding and Lloyd, 2021), which had a range of methodologies (Table 1). The four studies included a total of 152 clinicians, who were medical, nursing and allied health professional practitioners in both primary (n=148) and secondary (n=4) care settings, with a total of 51 patients. Sample sizes varied from 13 to 91 participants.
All studies were conducted in western countries: the UK (n=2) (Yap Kannan et al, 2016; Scott et al, 2019), New Zealand (n=1) (Ding and Lloyd, 2021) and Australia (n=1) (Weller at al, 2020).
Because of the variation in interventions and methods of data analysis, it was not possible to undertake a meta-analysis, so a thematic analysis of the studies was carried out. Findings from the four studies were grouped into eight shared themes: appropriateness of the ABPI tool; clinician education; referral process; access to appropriate equipment; lack of time to conduct the assessment; competence; associated costs; and role definition.
Themes
Theme 1: Appropriateness of the ABPI tool
A recurrent theme in all studies was the relevance and appropriateness of ABPI as a screening tool for PAD. All studies acknowledged that ABPI was the most frequently used investigation globally alongside a holistic assessment to assist in the diagnosis of PAD and assess a patient's suitability for lower limb compression therapy. As well as being efficient and non-invasive, it provided valid, accurate and reliable results (Yap Kannan et al, 2016; Scott et al, 2019; Weller et al, 2020; Ding and Lloyd, 2021).
The studies focused on primary care medical and nursing staff and their experiences of ABPI assessment (Yap Kannan et al, 2016; Scott et al, 2019; Weller et al, 2020), with one study examining the experiences of secondary care clinicians, who were medical and allied health professionals (Ding and Lloyd, 2021). In all studies, the practitioners interviewed were aware of ABPI.
Ding and Lloyd (2021) acknowledged that international guidelines recommend the use of ABPI in both primary and secondary care settings when undertaking a vascular assessment or initiating treatment for VLUs. The studies conducted in the UK (Yap Kannan et al, 2016; Weller et al, 2020) acknowledged that ABPI was recognised within national guidance and best practice statements as gold-standard practice and was predominately undertaken in primary care settings, including GP practices and specialist community services facilitated by community nurses, practice nurses and specialist tissue viability nurses.
Yap Kannan et al (2016) highlighted that ABPI could be used to assess both asymptomatic and symptomatic presentations of PAD, with ABPI being more useful for assessing at-risk patients, such as those who are elderly, are smokers or have diabetes or chronic renal failure, than those who are healthy.
Although this theme suggests that ABPI is recognised as the gold standard assessment tool, it also highlights the lack of research and investigation of alternative methods such as automated devices, multi-site photoplethysmography or risk identification screening frameworks (Welsh et al, 2016; Scott et al, 2019). Within the studies, contraindication and limitations of the use of ABPI assessment were acknowledged but there is lack of clarity in the papers about alternative assessment methods.
Theme 2: Clinician education
Education was a further recurring theme, with variations found between clinicians' practice, which indicated inconsistencies between standards of baseline training, postregistration education and clinical exposure to performing ABPI assessments that potentially affected care delivery and patient experience (Yap Kannan et al, 2016; Scott et al, 2019; Weller et al, 2020; Ding and Lloyd, 2021). These studies said a standard, universal approach in education and training to undertaking ABPI assessment was needed to ensure consistency in patient care and experience.
This knowledge gap was further explored by Weller et al (2020) and Ding and Lloyd (2021), who noted there was a lack of investment in staff training and development because of demand for services, high staff turnover, in-house training not being regulated or quality assured and the costs of conducting the assessment, which cannot be reimbursed in New Zealand and Australia.
Knowledge gaps in clinical staff undertaking assessments within the UK were also discussed (Yap Kannan et al, 2016; Scott et al, 2019). Scott et al (2019) suggested in-depth knowledge could improve clinician confidence, while enabling them to provide a comprehensive diagnosis, with an accurate ABPI result giving further reassurance.
This theme highlights the need to address the knowledge gap and develop standardised training packages that are incorporated into both undergraduate and postgraduate education to ensure strong foundations and that theory-informed clinical practice will be implemented (Weller et al, 2020).
Theme 3: Referral process
Ding and Lloyd (2021) considered the referral process for clinicians and need for support from specialist services when providing primary care services. They examined the value of clear referral criteria and pitfalls experienced by clinicians when there was a lack of consistent practice and underpinning clinical information to support an appropriate referral. They acknowledged that practice within New Zealand saw clinicians referring patients to secondary care specialists to make diagnoses and to initiate treatment because of guidelines and best practice statements to inform clinical decision-making are unclear Ding and Lloyd (2021).
In contrast, Yap Kannan et al (2016) suggested there was minimal clinical involvement of specialist clinicians in the UK, potentially because of NICE guidance and supplementary best practice guidance, with many VLU patients being managed by nursing staff, and having successful healing outcomes.
Both studies suggested that unclear diagnostic and referral guidance were overarching problems. They highlighted the need for consistency in both the diagnosis and management of PAD and VLUs to ensure the quality of patient care was consistent and overcome the undefined role definition of clinicians, and for referral processes to be simple and transparent for the referring practitioner and patient alike.
Theme 4: Access to appropriate equipment
The studies included within the review alluded to ABPI being a challenge within their clinical area because equipment was lacking, not adequate for purpose or not standardised, which impacted ABPI assessment globally and directly affected patient assessment and treatment outcomes (Weller et al, 2020; Ding and Lloyd, 2021). Both of these studies suggested there was no universal standard equipment requirement and that requests to commissioning groups and practice partners to obtain devices to meet service needs had been denied.
Furthermore, this has been voiced through the experiences of GPs and practice nurses, suggesting that equipment requests to undertake an accurate ABPI assessment are denied, or devices are not freely available because few patients require assessment for VLUs, and need a referral to secondary care settings for this (Weller et al, 2020; Ding and Lloyd, 2021).
Weller et al (2020) suggested this equipment was available only for services providing diabetic screening and those that monitor patients with other risk factors, questioning the equity in service provisions for these two groups of patients.
Theme 5: Lack of time to conduct the assessment
Although making every contact count has been of great importance to all clinicians, time constraints have been voiced as a barrier to using the ABPI tool by clinicians in the studies examined, with Ding and Lloyd (2021:168) reporting:
‘You don't have much time in general practice. You have people coming through, and you don't want something that's going to slow you down.
‘You've got to balance that with doing ABPIs in your consult, as well as not holding up the next person.’
Ding and Lloyd (2021) and Weller et al (2020) admitted that many clinicians believed they were assigned insufficient time to perform ABPI assessments and most of the consultation was taken up with dressing the wound and, potentially, not providing holistic care. Weller et al's (2020) study suggested that a 10-minute appointment slot allocated for both GP and nursing appointments was not long enough, and it is worth noting that, in reality, appointments last for up to 30 minutes, as the authors are aware that patients often require further investigation.
There are financial implications for primary care providers, as reimbursement for this additional time is not available in Australia, despite ABPI being classed as a specialised tool (Weller at al, 2020).
Theme 6: Competence
The four studies found clinician competence impacted their willingness to conduct ABPI assessments; practitioners lacked both exposure to the assessment tool and support to interpret the results and make a confident diagnosis (Yap Kannan et al, 2016; Scott et al, 2019; Ding and Lloyd, 2021).
This theme is closely linked with clinician education and the need to develop clear diagnostic guidance and clinician competence frameworks to align practice to.
Ding and Lloyd (2021) explored this through clinician experience, suggesting that practitioners resist carrying out an ABPI assessment because they do not perform such assessments regularly, so lack a consistent approach to diagnosis, and are over-reliant on the presentation of symptoms rather than an ABPI reading.
Similarly, Scott et al (2019) argued that the different experiences of non-specialist staff and the skill mix required (including dexterity, knowledge and experience to improve the patient's experience by reducing anxiety and discomfort) and knowledge made it difficult for them to interpret results and develop an appropriate management plan.
All four studies in this review recognised the need for collaboration between GP practices, community nursing services and specialist services to develop and enhance education to perform ABPI and improve wound care services (Yap Kannan, 2016; Scott et al, 2019; Ding and Lloyd, 2021).
Ding and Lloyd (2021) said a lead role within GP practices was needed, with the development of a specialist clinician to undertake ABPI assessment and deliver a more consistent approach to assessment, while ensuring the examining clinician felt confident in their decision-making skills.
Theme 7: Associated costs
Initial investment in clinical equipment and education, plus costs of maintenance and unforeseen associated expenses, put a long-term financial burden on already-stretched primary care services both globally and in the UK, and contribute to the reluctance to provide ABPI assessment services (Yap Kannan et al, 2016; Ding and Lloyd, 2021).
Nevertheless, despite the high initial outlay required, early diagnosis would help to reduce the overall financial burden of VLUs and hard-to-heal wounds, and improving services would have a positive impact on patient outcomes (Weller et al, 2020).
Theme 8: Role definition
The need for recognition of ABPI as a specialist skill, requiring additional targeted training and role recognition, empowering staff, was explored (Yap Kannan et al, 2016; Weller et al, 2020; Ding and Lloyd, 2021).
Yap Kannan et al (2016) suggested ABPI fit into the remit of nursing as nurses were often patient facing and had regular, continuing contact with patients throughout their journeys.
Weller et al (2020) proposed that ABPI should be undertaken by a clinician with a specialist interest and training who can facilitate a lead role to oversee the practices of ABPI assessment to ensure consistency and provide quality assurance.
Discussion
Is ABPI a safe and effective screening tool for PAD?
ABPI is acknowledged to be a non-invasive, valuable and comprehensive assessment and diagnosis tool for PAD, and is used in westernised countries that provide publicly funded healthcare (Crawford et al, 2016; Yap Kannan et al, 2016; Welsh et al, 2016; Guest et al, 2018; Scott et al, 2019; Weller et al, 2020; Ding and Lloyd, 2021).
The most recent British Lymphology Society (2018) guidance further strengthened and supported the use of ABPI assessment as part of routine assessment, where not contraindicated, for the initiation of compression therapy.
All four research papers in this review examined and referred to governing guidelines supporting clinical practice but noted they lacked clarity and consistency. Guest et al (2018), Welsh et al (2016), Yap Kannan et al (2016) and Scott et al (2019) acknowledged best practice statements and the National Institute for Health and Care Excellence (NICE) clinical knowledge summaries suggesting that ABPI assessment was fundamental when screening for PAD, in diabetic foot assessment, when assessing non-healing wounds and when considering compression therapy as per gold-standard practice (NICE, 2021; 2022). This review found that, despite clinical recommendations, practice varied, affecting patient care.
The findings of this review suggest that, despite the publication of national guidance and supplementary best practice statements from key opinion leaders and professional organisations, universal guidance and referral policies are needed to ensure consistency in practice and patient experience. This is required both in UK and internationally to promote consistency when identifying at-risk patients and undertaking ABPI assessment.
Is ABPI the most appropriate method of assessing suitability for compression?
The review found many clinicians said ABPI was the only method available of assessing a patient's suitability for lower limb compression therapy.
Throughout the four studies, ABPI was recognised mostly for supporting a diagnosis of PAD and assessing suitability for compression therapy. However, the need for a holistic patient assessment was not always acknowledged, with the focus being the need for a numerical reading, again adding to the hesitance of clinicians to perform the assessment because they were unable to obtain such readings.
Guest et al (2018) and Welsh et al (2016) agreed a holistic assessment should be conducted as part of the leg assessment. Such an assessment should include a full medical history review, lifestyle assessment and physical examination of the lower limb (Payne, 2019).
Furthermore, ABPI may be contraindicated in some patients because they are unable to tolerate the assessment or have other comorbidities, which means they are not suitable for this form of assessment. However, a compression therapy suitability screening tool is required so patients at high risk receive equitable and timely treatment to manage their condition.
The review showed than many clinicians felt ABPI was a specialist skill and required training, with some suggesting a specialist role was needed to ensure attainment and assessment of readings were done correctly. Many clinicians lacked confidence as they did not perform the process regularly, again acknowledging the need for an alternative screening tool that would be more user friendly and require less resourcing.
Guest et al (2018) highlighted that, even if ABPI was not assessed or recorded correctly and the patient did not receive compression therapy, VLUs still healed successfully. They further questioned the use of compression theory in low-risk patients, such as those with no past medical history, as their rates of healing were comparable to those who did not receive compression therapy. This requires further research to examine more measurable outcomes as well as an examination of clinical practice.
Recommendations for practice arising from the findings are outlined in Box 1.
Box 1.Recommendations for practice
- Universal guidance should be implemented to ensure consistency in ankle–brachial pressure index (ABPI) assessment. A competence framework would ensure specialist educational training and standards
- A standardised equipment checklist is needed for clinical services performing the procedure
- A risk assessment screening tool is required so clinicians can assess a patient's suitability for ABPI assessment, acknowledging contraindications and treatment recommendations, alongside holistic leg assessment
- Research should be carried out into the use of automated ABPI measurements for assessment and monitoring, and an APBI specialist role
Limitations
Only papers written in English were retrieved, so key papers may have been excluded.
Conclusion
This review identifies the following issues have implications for clinical practice: the lack of clinician education and maintenance of competency; time constraints experienced by frontline clinicians; a lack of clear supporting diagnosis and referral guidance; and access to appropriate equipment to perform the assessment correctly.
The qualitative approach of this review meant that perceptions and experiences of both clinicians and patients were examined. Quantitative research should be conducted to provide more measurable outcomes to support the development and implementation of recommendations for clinical practice.
ABPI is the most used assessment tool to ensure the early identification, diagnosis and management of PAD and lower limb conditions that may require compression therapy. The review highlighted the importance of undertaking a holistic assessment of patients, incorporating an ABPI assessment for all patients where not contraindicated.
Analysis of the included papers has highlighted the need for further research to explore patient experience and safety when assessing a patient's suitability for lower limb compression therapy. BJN
KEY POINTS
- Ankle–brachial pressure index (ABPI) is an effective assessment screening tool for early identification of peripheral artery disease and assessing suitability for lower limb compression therapy
- ABPI should not be used in isolation but as part of a holistic patient assessment
- Barriers to ABPI assessment include clinician confidence and access to appropriate equipment
- Further research is required into alternative assessment methods for patients in whom ABPI assessment is contraindicated
CPD reflective questions
- How often do you undertake ankie–brachial pressure index assessment in your clinical practice and what do you feel would help to develop your confidence in doing this?
- Can you identify barriers and enablers that impact on the implementation of lower limb compression therapy in your clinical area?
- What important things can be learned from this review?