Toe pressure for persons with difficult-to-heal wounds

Peripheral artery disease (PAD) is due to arterial insufficiency which results in decreased blood circulation in the arteries and is common in atherosclerosis. In the event of severe impaired blood circulation, there is a risk of difficult-to-heal wounds and cold sores. To diagnose arterial insufficiency one can measure the systolic blood pressure in either the toe or ankle and by combining this with a blood pressure measurement in the arm and then calculate the toe (TBI) or ankle-brachial index (ABI).

Question

What systematic reviews are there on the diagnostic accuracy and prognosis of toe pressure measurements for people with difficult-to-heal wounds?

Identified literature

Table 1. Systematic reviews with low/medium risk of bias concerning diagnostic accuracy of TBI or TBSP for the diagnosis of PAD.
TBI = Toe brachial index; TSBP = Toe systolic blood pressure; TBPI = Toe brachial pressure index; ABI = Ankle brachial index; PAD = Peripheral arterial disease; DUS = Duplex ultrasonography; CTA = Computed tomography angiography; MRA = Magnetic resonance angiography, DSA = Digital subtraction angiography
Included studiesPopulation/InterventionOutcome and Results
Normahani et al, 2021.
A systematic review and meta-analysis of the diagnostic accuracy of point-of-care tests used to establish the presence of peripheral arterial disease in people with diabetes [1].
Included studies: The review included 18 studies of which 11 studies (1543 limbs) were included in the meta-analysis of diagnostic accuracy.
TBI: 3 studies
ABI: 9 studies

Risk of bias: Moderate
Population: People with diabetes.

Index test: Bedside tests such as TBI and ABI for the detection of PAD.

Reference test: Full lower limb DUS, CTA, MRA, or DSA.
Outcome: Detection of PAD

Sensitivity: 
TBI: 83.0 (95% CI, 59.1 to 94.3) %
ABI: 63.5 (95% CI, 51.7 to 73.9) %

Specificity:
TBI: 66.3 (95% CI, 41.3 to 84.6) %
ABI: 89.3 (95% CI, 81.1 to 94.2) %
Authors' conclusion:
“TBI/TBPI, pulse oximetry, and ankle arterial waveform assessment have demonstrated some promising results that warrant further investigation in a robust prospective diagnostic accuracy study. Given the disappointingly poor sensitivity of ABPI [ankle brachial pressure index] and the lack of evidence for its performance when used in combination with other tests, we cannot at present recommend it as a rule out test for PAD in people with diabetes. Although further evidence is awaited, we recommend that all patients with active diabetic foot ulceration undergo full lower limb DUS for the assessment of PAD.”
Herraiz-Adillo et al, 2020.
The accuracy of toe brachial index and ankle brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis [2]
Included studies: The review included 49 studies.
TBI: 15 studies of which 9 in meta-analysis.
ABI: 42 studies of which 35 in meta-analysis.

RoB: Moderate
No information on article screening process (single or double)
Population:
Adults ≥18 years

Index test: TBI and ABI

Reference test: DUS, angiography, CTA or MRA
Outcome: Detection of PAD

Sensitivity:
TBI: 82 (95% CI, 69 to 97) %
ABI: 52 (95% CI, 42 to 65) %

Specificity:
TBI: 77 (95% CI, 65 to 92) %
ABI: 94 (95% CI, 88 to 100) %
Authors' conclusion:
“ABI and TBI showed acceptable diagnostic performance to diagnose PAD in clinical practice, with TBI exhibiting far better sensitivities (but lower specificities) than ABI, especially in “challenging populations”, as those exhibiting calcification. This meta-analysis identified different variables accounting for heterogeneity, which was large in sensitivity regarding ABI and moderate in specificity regarding TBI, somehow limiting the extrapolation of pooled estimates to clinical practice.”

 

Table 2. Systematic reviews with low/medium risk of bias reporting on the capacity of TBI or TBP to predict impaired healing or risk of amputation.
TBI = Toe brachial index; TBP = Toe blood pressure; TBSP = Toe blood pressure; ABI = Ankle brachial index; PAD = Peripheral arterial disease; DFU = Diabetic foot ulcers; RR = Risk ratio; PLR = Positive likelihood ratio; NLR = Negative likelihood ratio; TcPO2 = Transcutaneous oxygen pressure
Included studiesPopulation/InterventionOutcome and Results
Linton et al, 2020
Do toe blood pressures predict healing after minor lower limb amputation in people with diabetes? A systematic review and meta-analysis. [3]
Included studies: The review included a total of 10 studies.
Where of 7 of these were unique and was not included in any of the other included reviews.

Risk for bias: Moderate
Population: Patients with diabetes that went through a minor lower limb amputation.

Intervention: TBP or TBI.

Control: The control in these studies were individuals with a higher TBP or TBI then certain threshold-values.
Nine studies investigating TBP reported healing occurred at mean TBP values ⩾30 mmHg, ranging between 30 and 83.6 mmHg.

Risk of non-healing post-minor foot amputation with a TBP of <30 mmHg
(4 studies, n=104)
Risk ratio: 2.09 (95% CI, 1.37 to 3.20)
Authors' conclusion:
“TBPI [toe brachial pressure index] or TSBP [toe systolic blood pressure] thresholds for prediction of healing post-minor amputations in the foot in people with diabetes varied considerably between the studies. However, all of the nine studies investigating TSBPs reported improved healing outcomes where mean TSBPs ⩾30 mmHg, with a range of 30–83.6 mmHg. Meta-analysis results showed a RR of non-healing post amputation of 2.09 (95% CI, 1.37 to 3.20, p=0.001) with TSBPs <30 mmHg compared to TSBPs ⩾30 mmHg. As only one study was identified that investigated the capacity for TBPI to predict post-amputation healing, no firm conclusions could be drawn. Identification of definite TSBP or TBPI thresholds associated with positive healing outcomes post minor foot amputation as complicated by heterogeneity present in the surgical cohorts and surgical techniques, vascular measurement methods and follow-up time periods. ”
Sonter et al, 2020
The predictive capacity of toe blood pressure and the toe brachial index for foot wound healing and amputation: A systematic review and meta-analysis. [4]
Included studies: The review included a total of 10 studies.
Where of 5 of these were unique and was not included in any of the other included reviews.

Risk for bias: Moderate
Population: People with poor peripheral blood flow or a foot wound referred to a vascular or high-risk foot clinic.
Studies on healing following surgery (including amputation) or other treatments were excluded.

Intervention: TBP or TBI.
Studies comparing measurement techniques or devices were excluded.

Control: The control in these studies were individuals with a higher TBSP or TBI then certain threshold-values.
All studies were in favour of increased risk of non-healing or amputation with a pressure of <30 mmHg.

Risk of non-healing with a TBP of <30 mmHg
7 studies, n was not reported.
Risk ratio: 3.25 (95% CI, 1.96 to 5.41)
Authors' conclusion:
“The limited evidence available supports an association between TSBP [toe systolic blood pressure] and the TBI with wound healing and risk of amputation. A cut-off value of 30 mmHg was found to be associated with a 3.25 times greater risk of non-healing or amputation. Further benefit would likely be gained with the use of multiple assessments and the development of a grading system for TSBP and TBI values.”
Tay et al, 2020
Toe Pressure in Predicting Diabetic Foot Ulcer Healing: A Systematic Review and Meta-analysis. [5]
Included studies: The review included a total of 8 studies.
Where of 0 of these were unique and was not included in any of the other included reviews.

Risk for bias: Moderate
Population: Patients with both diabetes and an ulcer of the lower extremity

Index test:
TBP
Only study designs including 30 or more patients were selected
Prediction of wound healing with a TBP of >30 mmHg.
8 studies, n=909
Sensitivity: 0.86 (95% CI, 0.82 to 0.89)
Specificity: 0.58 (95% CI, 0.52 to 0.63)
Authors' onclusion:
“Based on the existing literature, a TBP of more than 30 mm Hg is sensitive but not specific in the prediction of healing of DFUs. Given the portable nature of TBP measurement devices and ease of TBP measurement, it has great value as a quick bedside assessment to complement current clinical parameters to aid in predicting the healing of DFUs. More recent studies with standardized participant data should be carried out to determine its relevance in today’s clinical context as an indication of DFU healing potential.”
Forsythe et al, 2019
Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: A systematic review. [6]
Included studies: The review included a total of 15 studies, only 5 of these evaluated tests based on toe-pressure. The most common test was ankle-brachial index (ABI) or ankle pressure (n=10).

Risk of bias: Moderate

This systematic review was an updated version of an older publication [7].
Population: Patients with both diabetes and foot ulceration

Index test: Non-invasive bedside tests, including clinical examination, ankle and toe pressures/indices, Doppler waveform analysis, transcutaneous oxygen pressure (TcPO2), laser Doppler imaging, pole test, and objective measures of skin temperature.

Reference test: Gold standard tests used to diagnose PAD included magnetic resonance angiography (MRA), computed tomographic angiography (CTA), and digital subtraction angiography (DSA).
Prediction of wound healing with a toe pressure of ≥30 mmHg. (4 studies)
PLR: 1.12 to 5.00
NLR: 0.28 to 0.88

Prediction of wound healing with an ankle pressure of ≥50 mmHg. (2 studies)
PLR:
1.08 to 1.46
NLR:
0.28 to 0.88

Prediction of wound healing with a normal ABI
A normal ABI was not strongly predictive of healing in 3 of 4 studies.

The review also includes several results (both toe- and ankle pressure tests) from single studies on different thresholds on risk for amputation and wound healing.
Authors' conclusion:
“Among the 15 studies included in this review, comprising almost 6800 patients with a diabetic foot ulcer, the presence of severe perfusion deficit (ankle pressure <50 mmHg, ABI <0.5, toe pressure <30 mmHg, and TcPO2 <25 mmHg) was associated with greater than 25% increased risk of major amputation, while a better perfused foot (skin perfusion pressure ≥40 mmHg, toe pressure ≥30 mmHg, or TcPO2 ≥25 mmHg) was found to be more likely to heal. These measures of PAD may be used as a guide when deciding management of patients, and the likelihood of healing or major amputation can be incorporated into the decision to pursue conservative management or a further vascular assessment potentially leading to revascularization.”

References

  1. Normahani P, Mustafa C, Shalhoub J, Davies AH, Norrie J, Sounderajah V, et al. A systematic review and meta-analysis of the diagnostic accuracy of point-of-care tests used to establish the presence of peripheral arterial disease in people with diabetes. J Vasc Surg 2021;73:1811-1820.
  2. Herraiz-Adillo A, Cavero-Redondo I, Alvarez-Bueno C, Pozuelo-Carrascosa DP, Solera-Martinez M. The accuracy of toe brachial index and ankle brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis. Atherosclerosis 2020;315:81-92.
  3. Linton C, Searle A, Hawke F, Tehan PE, Sebastian M, Chuter V. Do toe blood pressures predict healing after minor lower limb amputation in people with diabetes? A systematic review and meta-analysis. Diab Vasc Dis Res 2020;17:1479164120928868.
  4. Sonter JA, Ho A, Chuter VH. The predictive capacity of toe blood pressure and the toe brachial index for foot wound healing and amputation: A systematic review and meta-analysis. Wound Practice & Research 2014;22:208-220.
  5. Tay WL, Lo ZJ, Hong Q, Yong E, Chandrasekar S, Tan GWL. Toe Pressure in Predicting Diabetic Foot Ulcer Healing: A Systematic Review and Meta-analysis. Ann Vasc Surg 2019;60:371-378.
  6. Forsythe RO, Apelqvist J, Boyko EJ, Fitridge R, Hong JP, Katsanos K, et al. Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: A systematic review. Diabetes Metab Res Rev 2020;36 Suppl 1:e3278.
  7. Brownrigg JR, Hinchliffe RJ, Apelqvist J, Boyko EJ, Fitridge R, Mills JL, et al. Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: a systematic review. Diabetes Metab Res Rev 2016;32 Suppl 1:128-35.

SBU Enquiry Service Consists of structured literature searches to highlight studies that can address questions received by the SBU Enquiry Service from Swedish healthcare or social service providers. We assess the risk of bias in systematic reviews and when needed also quality and transferability of results in health economic studies. Relevant references are compiled by an SBU staff member, in consultation with an external expert when needed.

Published: 10/5/2021
Report no: ut202121
Registration no: SBU 2021/36