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Editor's Choice – The Prognostic Value of the WIfI Classification in Patients with Chronic Limb Threatening Ischaemia: A Systematic Review and Meta-Analysis
Corresponding author. Amsterdam UMC, University of Amsterdam, Amsterdam Cardiovascular Sciences, Department of Surgery, Meibergdreef 9, 1105AZ Amsterdam, the Netherlands.
The Society for Vascular Surgery has proposed the Wound, Ischaemia, and foot Infection (WIfI) classification system as a prognostic tool for the one year amputation risk and the added value of revascularisation in patients with chronic limb threatening ischaemia (CLTI). This systematic review summarises the current evidence on the prognostic value of the WIfI classification system in clinical practice.
Design
Systematic review and meta-analysis following the PRISMA guidelines.
Materials
The Embase, MEDLINE, and Cochrane databases were searched up to June 2018.
Methods
All studies using the WIfI classification for patients with CLTI were eligible. Outcomes of interest were major amputation, limb salvage, and amputation free survival in relation to WIfI clinical stage. The methodological quality of studies was appraised with the Quality in Prognosis Studies (QUIPS) tool. If possible, data were pooled and analysed using a random effects model. Study selection, quality assessment, and data extraction were carried out by two authors independently.
Results
The search yielded 12 studies comprising 2669 patients, most of whom underwent endovascular or open revascularisation. Overall study quality was moderate. All but one were retrospective studies, including a variety of subpopulations of patients with CLTI, such as only haemodialysis dependent, diabetic or non-diabetic patients. The WIfI classification was derived from chart data or prospectively maintained databases, both documented before the WIfI classification was published. Estimated one year major amputation rates from four studies comprising 569 patients were 0%, 8% (95% CI 3–21%), 11% (95% CI 6–18%) and 38% (95% CI 21–58%), for WIfI stages I–IV, respectively.
Conclusions
The likelihood of an amputation after one year in patients with CLTI increases with higher WIfI stages, which is important prognostic information. Prospective evaluations are needed to determine its role in clinical practice.
The Society for Vascular Surgery Wound Ischaemia and foot Infection (WIfI) classification has been developed as a tool to help clinical decision making in patients with CLTI. This systematic review shows that the WIfI classification can, to some extent, predict major amputation after one year. However, the current evidence is not sufficient for the instrument to be helpful in clinical decision making for patients with CLTI.
Introduction
Since critical limb ischaemia was defined in 1982, the epidemiology of patients presenting with this diagnosis has changed.
To reflect these changes the 2017 ESC/ESVS (European Society of Cardiology/European Society for Vascular Surgery) guideline on the diagnosis and treatment of peripheral arterial disease has replaced the term critical limb ischaemia with chronic limb threatening ischaemia (CLTI).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Three arguments were given for this change; first, not all patients suffering from this disease are ‘critical’ at risk of losing their affected limb even in the absence of revascularisation. Second, due to the increase in diabetes and neuro-ischaemic ulcers it was pointed out that severe ischaemia is not the only underlying cause.
The third reason was that the risk of amputation does not entirely depend on the extent of ischaemia but also on the presence of a wound and infection.
Separate classification systems have been used for patients with ischaemia (i.e. Rutherford and Fontaine) or for patients with a diabetic foot (i.e. Wagner and Texas). In 2014, Mills et al.
The society for vascular Surgery lower extremity threatened limb classification system: risk stratification based on wound, ischemia, and foot infection (WIfI).
stated that the existing classification systems neither took into account the natural history of CLTI nor assessed or graded the major risk factors that influence limb loss and clinical management. Hence, they presented a new classification system to be used to predict the one year amputation risk and the added value of a revascularisation. The determinants of these two outcomes were the presence and dimensions of wound or tissue loss, the presence and grade of infection, and the severity of ischaemia, each scored on a scale from 0 to 3. By means of a Delphi consensus these three determinants were combined into a clinical risk score, ranging from very low (1) to high (4). This is currently known as the Wound, Infection, and Ischaemia (WIfI) classification system for the risk of amputation after one year, and the benefit or requirement of revascularisation. The classification and the clinical scores are shown in Tables S2 and S3.
Multiple studies have evaluated the prognostic value of the WIfI classification as summarised in the scoping review by Mills.
Some of these studies showed that the risk of amputation increased with a higher WIfI grade but predominantly included diabetic patients or those who underwent revascularisation.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
In order to evaluate the prognostic value of this new classification system in all CLTI patients, the available evidence was reviewed regarding the value of the WIfI classification in patients presenting with CLTI to predict the one year major amputation risk and the benefit of revascularisation.
Materials and Methods
This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement.
The protocol was registered as PROSPERO CRD42018086641.
Literature search
With the aid of a clinical librarian a systematic literature search was created to query the Embase, MEDLINE, and Cochrane databases from their inception to June 2018. The full search strategy is shown in Table S1. No language or other restrictions were applied.
Eligibility criteria
Studies were eligible if they included patients with diabetic foot ulcers and/or CLTI and evaluated the prognostic value of the WIfI classification system regardless of revascularisation or revascularisation method and duration of follow up. Articles published before 2014 were excluded since the original article on the WIfI classification was published in 2014. Titles and abstracts were screened independently by two reviewers (N.R., K.P.). Discrepancies were resolved by discussion or by a third arbitrator. Subsequently, full texts were retrieved and screened independently by two reviewers (N.R., K.P.). Again, discrepancies were resolved by discussion.
Data extraction and outcomes
Data were extracted independently by the same two authors (N.R., K.P.) and recorded on a predefined form. Study characteristics extracted were study design, inclusion and exclusion criteria, type of treatment, endpoints, follow up period, restaging of the WIfI classification, and baseline patient characteristics such as age, gender, diabetes, renal disease, or dialysis dependence. The outcomes of interest were major amputation (amputation level at which the foot is not sufficiently functional to allow walking without a prosthesis), limb salvage (no major amputation with healing of ulcers), and amputation free survival (AFS, composite of patient being alive without major amputation).
The methodological quality assessment of the individual studies was performed independently by two reviewers (N.R., K.P.) using the Quality in Prognosis Studies (QUIPS) tool.
A GRADE table was created with GRADEPRO for the certainty of evidence on the three outcomes, namely major amputation, AFS, and limb salvage after one year.
The DerSimonian and Laird random effects model was chosen a priori to calculate the pooled risk and 95% confidence interval (CI) for major amputation after one year, limb salvage after one year, and one year AFS because of presumed clinical heterogeneity between studies. The amount of statistical heterogeneity between studies was assessed using the I
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
statistic. Statistical analyses were conducted using R-Studio (R-Studio Inc., Boston, MA, USA). Analysis of publication bias was not carried out because of the low number of studies eventually included in the systematic review.
Results
Study selection
The search yielded a total of 1702 studies of which 12 were included for qualitative analysis (Fig. 1).
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system following infrapopliteal endovascular interventions for critical limb ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
the other eight in the United States (Table 2). The studies included different populations of patients presenting with CLTI. For example, one study included only patients with diabetes,
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The other six studies included also patients with conservative treatment (Table 3). The WIfI classification was determined either at presentation, admission, or pre-operatively, two studies did not specify this (Table 2).
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
CLI: ABI ≤ 0.40 and/or rest pain and/or with(out) tissue loss in presence of PAD, Rutherford 4–6, >2 weeks CLI. Only one leg per patient, first treatment
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Table 3Methodological assessment of individual studies (Quality in Prognosis Studies).
Table 3Methodological assessment of individual studies (Quality in Prognosis Studies).
Methodological quality assessment
The methodological quality assessment of the studies is presented in Table 3. Statistical analysis and reporting was good in all studies. Five of the 12 studies did not report attrition of patients during the study period,
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The certainty of evidence was low to very low for all three outcomes according to the GRADE approach. Full details are presented in Table S4.
Outcomes
An overview of the outcomes extracted from the studies is shown in Table 4, Table 5. The outcomes were either reported per patient or if noted, per limb. Three studies were excluded from meta-analysis, because they did not report their outcomes after one year of follow up.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
was excluded from the meta-analysis on clinical grounds because they only included diabetic foot ulcer patients with and without peripheral arterial disease. Five studies performed a multivariable analysis for the WIfI classification on major amputation, as shown in Table 4.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
used it as a tool for post-revascularisation staging and expressed the outcomes per determinant (i.e. wound, ischaemia, foot infection) and not per clinical stage. Darling et al.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
reported a WIfI composite score (i.e. a cumulative score of the individual determinants) and a WIfI mean score (i.e. the cumulative score of the individual determinants divided by the number of known determinants). This was done in order to weigh the individual determinants equally. The mean score allowed use of the classification in case not all determinants were known.
Meta-analyses
Major amputation after one year
Data for each WIfI stage from four studies (569 patients, 575 limbs) reporting on major amputation were pooled.
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
= 93%) for stage IV). The GRADE certainty of evidence on limb salvage ranged from low to very low (Table 6, Table S4).
Discussion
The Society for Vascular Surgery introduced the WIfI classification to provide information regarding the risk of major amputation within one year and the benefit of revascularisation in patients with CLTI. This review shows that the likelihood of a major amputation after one year in patients with CLTI does increase with higher clinical WIfI stages, especially in stage IV. Similarly, the higher the WIfI stage, the lower AFS and limb salvage rates after one year.
Sufficient evidence was not found to support the use of the WIfI classification to predict the benefit of revascularisation. The study by Robinson et al.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
presented the benefit of restaging the classification after revascularisation but only presented the outcomes of the individual determinants (i.e. wound, ischaemia, foot infection) and not the clinical stage. Furthermore, they only presented post-operative results of staging WIfI, which makes the interpretation of their results on the benefit of restaging, and therefore benefit of revascularisation difficult. This review has some limitations. The included studies comprised a diverging range of patients: hospitalised vs. outpatient treatment, patients requiring haemodialysis, invasively or conservatively treated patients, and diabetic or non-diabetic patients. For this reason, individual studies showed different results. For example, major amputation rates after one year in the study of Beropoulis et al.,
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
who included non-diabetic patients treated by endovascular revascularisation, were not considerably different for clinical WIfI stages I and IV (0% and 12%, respectively). In contrast, in the study by Zhan et al.,
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
in which only hospitalised, mostly diabetic patients were included and a large proportion of patients were treated conservatively, one year amputation rates were 0% and 64%, respectively. This could partly explain the statistical heterogeneity in the meta-analyses for WIfI stage IV on Major amputation and stage II–IV on Limb salvage (Table 6).
Second, after the WIfI classification was published in 2014, it has been evaluated in only one prospective study.
The other studies were retrospective analyses of data from charts or electronic medical records, or from prospectively maintained databases in which the data were collected before the introduction of the WIfI classification. Hence, only patients with sufficient data to determine the WIfI classification were suitable to be included in these studies. However, we do not think this has skewed the findings.
Furthermore, it is possible that, due to the inclusion criteria of the individual studies, only patients with either a good or a poor prognosis were included. This would yield results of outliers and not the average patient with CLTI. Also, it is conceivable that converting information from medical charts on wounds and infection to grade WIfI stages is imprecise, because the exact information islikely to be missing. This could result in information bias.
Finally, although the concept of the classification is promising, it only takes into account the status of the affected limb and not the patients’ comorbidities or overall condition. These determinants are well known to influence the course and management of the affected limb.
Risk stratification in critical limb ischemia: derivation and validation of a model to predict amputation-free survival using multicenter surgical outcomes data.
Validation of the PIII CLI risk score for the prediction of amputation-free survival in patients undergoing infrainguinal autogenous vein bypass for critical limb ischemia.
In daily practice, vascular surgeons determine the optimum treatment not solely on the clinical status of the leg but on a more comprehensive view of the patient. Unfortunately, the multivariable analyses by Darling et al.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
did not include determinants other than WIfI, which ignores the association of other predictive factors for AFS, mortality, and amputation. In the study by Robinson et al.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
revascularisation lowered the risk of amputation, whereas this risk increased with a higher WIfI stage. However, in four studies reporting on the WIfI classification in multivariable analyses on major amputation, the reference group was not presented (Table 4).
At present the classification gives a global indication of the prognosis, the logical next step is to determine its value as an instrument to guide clinical decision making. Ideally, this is done in future multicentre studies registering the WIfI classification prospectively in all patients presenting with CLTI.
Conclusion
The likelihood of an amputation after one year in patients with CLTI increases with higher WIfI stages, which is important prognostic information. Prospective evaluations are needed to determine its role in clinical practice.
Conflict of Interest
None.
Funding
This work was supported by the Netherlands Organisation for Health Research and Development (ZonMw) grant no. 843004106. ZonMw did not play any role in the conduct and writing of this research.
Acknowledgements
We would like to thank Faridi S. van Etten-Jamaludin, clinical librarian and medical information specialist, for her advice on the search strategies for this review.
Appendix A. Supplementary data
The following is the Supplementary data to this article:
Editor's choice - 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the european society for vascular Surgery (ESVS).
The society for vascular Surgery lower extremity threatened limb classification system: risk stratification based on wound, ischemia, and foot infection (WIfI).
Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia.
The Society for Vascular Surgery lower extremity threatened limb classification system based on Wound, Ischemia, and foot Infection (WIfI) correlates with risk of major amputation and time to wound healing.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system after first-time lower extremity revascularizations.
The Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system predicts wound healing but not major amputation in patients with diabetic foot ulcers treated in a multidisciplinary setting.
Society for Vascular Surgery Wound, Ischemia, foot Infection (WIfI) score correlates with the intensity of multimodal limb treatment and patient-centered outcomes in patients with threatened limbs managed in a limb preservation center.
Prognostic value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification in patients with no-option chronic limb-threatening ischemia.
Predictive ability of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system following infrapopliteal endovascular interventions for critical limb ischemia.
Risk stratification in critical limb ischemia: derivation and validation of a model to predict amputation-free survival using multicenter surgical outcomes data.
Validation of the PIII CLI risk score for the prediction of amputation-free survival in patients undergoing infrainguinal autogenous vein bypass for critical limb ischemia.
The past three decades have established that limb loss is a multifactorial process. Alongside this growing appreciation, tools have been developed to aid clinicians in stratifying patients into high and low risk groups. The Society for Vascular Surgery Wound, Ischaemia and foot Infection (WIfI) classification was born out of the recognition that existing classification systems had deficiencies in the description of at least one domain.1 For example the Rutherford classification provides a granular description of the effects of tissue ischaemia, but fails to account for the role of foot infection in limb loss.
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