The development and validation of a multivariable prognostic model to predict foot ulceration in diabetes using a systematic review and individual patient data meta-analyses

Effectiveness of screening for foot complications in people with diabetes - A systematic review

BACKGROUND

A quarter of people with diabetes develop foot ulcer in their lifetime and are six times more likely to require a major lower limb amputation compared to the general population. Risk stratification tools can reliably identify those at the highest risk of ulceration, but it remains unclear if screening for foot complications can prevent limb loss in people with diabetes.

AIMS

The aim of this systematic review was to determine whether population-based foot screening in people with diabetes reduces lower limb complications as assessed by development of foot ulceration, minor and major lower limb amputations, hospitalisation, or death.

METHODS

MEDLINE, Embase, Emcare and CINAHL databases were searched to identify randomised and non-randomised controlled trials and observational studies (cohort, case-control and cross-sectional surveys). The screening process, study quality assessment and data extraction were performed by two independent reviewers.

RESULTS

Following abstract screening and assessment for eligibility, five out of 10,771 identified studies were included in the analysis. Of these studies, one demonstrated 24 % reduction in development of new ulceration following introduction of screening. Major amputations decreased by between 17 and 96 % in three studies. Hospitalisation rates were contradictory, with one study showing doubling in hospital admissions and another one reduction by 33 %. One study demonstrated no impact of screening on minor or major amputation rates. None of the studies addressed the effect of foot screening on all-cause mortality.

CONCLUSIONS

The number and quality of studies to support population-based foot screening to prevent lower limb complications in people with diabetes is low. Current evidence suggests variable impact of screening on important clinical outcomes.

What characteristics are most important in stratifying patients into groups with different risk of diabetic foot ulceration?

AIMS/INTRODUCTION

This study aimed to assess if patients can be divided into different strata, and to explore if these correspond to the risk of diabetic foot complications.

MATERIALS AND METHODS

A set of 28 demographic, vascular, neurological and biomechanical measures from 2,284 (1,310 men, 974 women) patients were included in this study. A two-step cluster analysis technique  was utilised to divide the patients into groups, each with similar characteristics.

RESULTS

Only two distinct groups: group 1 (n = 1,199; 669 men, 530 women) and group 2 (n = 1,072; 636 men, 436 women) were identified. From continuous variables, the most important predictors of grouping were: ankle vibration perception threshold (16.9 ± 4.1 V vs 31.9 ± 7.4 V); hallux vibration perception threshold (16.1 ± 4.7 V vs 33.1 ± 7.9 V); knee vibration perception threshold (18.2 ± 5.1 V vs 30.1 ± 6.5 V); average temperature sensation threshold to cold (29.2 ± 1.1°C vs 26.7 ± 0.7°C) and hot (35.4 ± 1.8°C vs 39.5 ± 1.0°C) stimuli, and average temperature tolerance threshold to hot stimuli at the foot (43.4 ± 0.9°C vs 46.6 ± 1.3°C). From categorical variables, only impaired sensation to touch was found to have importance at the highest levels: 87.4% of those with normal sensation were in group 1; whereas group 2 comprised 95.1%, 99.3% and 90.5% of those with decreased, highly-decreased and absent sensation to touch, respectively. In addition, neuropathy (monofilament) was a moderately important predictor (importance level 0.52) of grouping with 26.2% of participants with neuropathy in group 1 versus 73.5% of participants with neuropathy in group 2. Ulceration during follow up was almost fivefold higher in group 2 versus group 1.

CONCLUSIONS

Impaired sensations to temperature, vibration and touch were shown to be the strongest factors in stratifying patients into two groups with one group having almost 5-fold risk of future foot ulceration compared to the other.

Prediction model for lower limb amputation in hospitalized diabetic foot patients using classification and regression trees

BACKGROUND

The decision to perform amputation of a limb in a patient with diabetic foot ulcer (DFU) is not an easy task. Prediction models aim to help the surgeon in decision making scenarios. Currently there are no prediction model to determine lower limb amputation during the first 30 days of hospitalization for patients with DFU.

METHODS

Classification And Regression Tree analysis was applied on data from a retrospective cohort of patients hospitalized for the management of diabetic foot ulcer, using an existing database from two Orthopaedics and Traumatology departments. The secondary analysis identified independent variables that can predict lower limb amputation (mayor or minor) during the first 30 days of hospitalization.

RESULTS

Of the 573 patients in the database, 290 feet underwent a lower limb amputation during the first 30 days of hospitalization. Six different models were developed using a loss matrix to evaluate the error of not detecting false negatives. The selected tree produced 13 terminal nodes and after the pruning process, only one division remained in the optimal tree (Sensitivity: 69%, Specificity: 75%, Area Under the Curve: 0.76, Complexity Parameter: 0.01, Error: 0.85). Among the studied variables, the Wagner classification with a cut-off grade of 3 exceeded others in its predicting capacity.

CONCLUSIONS

Wagner classification was the variable with the best capacity for predicting amputation within 30 days. Infectious state and vascular occlusion described indirectly by this classification reflects the importance of taking quick decisions in those patients with a higher compromise of these two conditions. Finally, an external validation of the model is still required.

LEVEL OF EVIDENCE

III.

Causes, prevention, and management of diabetes-related foot ulcers

In this Review, we aim to complement the 2023 update of the guidelines of the International Working Group on the Diabetic Foot. We highlight the complexity of the pathological processes that underlie diabetes-related foot ulceration (DFU) and draw attention to the potential implications for clinical management and outcome. Variation observed in the incidence and outcome of DFUs in different communities might result from differences in study populations and the accessibility of care. Comparing differences in incidence, management, and outcome of DFUs in different communities is an essential component of the quality of disease care. Additionally, these comparisons can also highlight the relationship between DFU incidence, management, and outcome and the structure of local clinical services and the availability of staff with the necessary skills. The clinical outcome is, however, also dependent on the availability of multidisciplinary care and the ability of people with DFUs to gain access to that care.

Two-year incidence and risk factors of diabetic foot ulcer: second phase report of Ahvaz diabetic foot cohort (ADFC) study

AIM/INTRODUCTION

This study was designed as the second phase of a prospective cohort study to evaluate the incidence and risk factors of diabetic foot ulcers (DFU).

MATERIALS AND METHODS

The study was conducted in a university hospital in Iran. Each participant was checked and followed up for two years in terms of developing newfound DFU as ultimate outcome. We investigated the variables using univariate analysis and then by backward elimination multiple logistic regression.

RESULTS

We followed up 901 eligible patients with diabetes for two years. The mean age of the participants was 53.24 ± 11.46 years, and 58.53% of them were female. The two-year cumulative incidence of diabetic foot ulcer was 8% (95% CI 0.071, 0.089) [Incidence rate: 49.9 /1000 person-years]. However, the second-year incidence which was coincident with the COVID-19 pandemic was higher than the first-year incidence (4.18% and 1.8%, respectively). Based on our analysis, the following variables were the main risk factors for DFU incidence: former history of DFU or amputation [OR = 76.5, 95% CI(33.45,174.97), P value < 0.001], ill-fitting foot-wear [OR = 10.38, 95% CI(4.47,24.12), P value < 0.001], smoking [OR = 3.87,95%CI(1.28, 11.71),P value = 0.016], lack of preventive foot care [OR = 2.91%CI(1.02,8.29),P value = 0.045], and insufficient physical activity[OR = 2.25,95% CI(0.95,5.35),P value = 0.066].

CONCLUSION

Overall, the two-year cumulative incidence of diabetic foot ulcer was 8% [Incidence rate: 49.9 /1000 person-years]; however, the second-year incidence was higher than the first-year incidence which was coincident with the COVID-19 pandemic (4.18% and 1.8%, respectively). Independent risk factors of DFU occurrence were prior history of DFU or amputation, ill-fitting footwear, smoking, lack of preventive foot care, and insufficient physical activity.

Clinical decision support systems for diabetic foot ulcers: a scoping review

OBJECTIVE

Map the scientific evidence on the use of clinical decision support systems in diabetic foot care.

METHOD

A scoping review based on the JBI Manual for Evidence Synthesis and registered on the Open Science Framework platform. Searches were carried out in primary and secondary sources on prototypes and computerized tools aimed at assisting patients with diabetic foot or at risk of having it, published in any language or period, in eleven databases and grey literature.

RESULTS

A total of 710 studies were identified and, following the eligibility criteria, 23 were selected, which portrayed the use of decision support systems in diabetic foot screening, predicting the risk of ulcers and amputations, classifying the stage of severity, deciding on the treatment plan, and evaluating the effectiveness of interventions, by processing data relating to clinical and sociodemographic information.

CONCLUSION

Expert systems stand out for their satisfactory results, with high precision and sensitivity when it comes to guiding and qualifying the decision-making process in diabetic foot prevention and care.

Risk of bias assessments in individual participant data meta-analyses of test accuracy and prediction models: a review shows improvements are needed

OBJECTIVES

Risk of bias assessments are important in meta-analyses of both aggregate and individual participant data (IPD). There is limited evidence on whether and how risk of bias of included studies or datasets in IPD meta-analyses (IPDMAs) is assessed. We review how risk of bias is currently assessed, reported, and incorporated in IPDMAs of test accuracy and clinical prediction model studies and provide recommendations for improvement.

STUDY DESIGN AND SETTING

We searched PubMed (January 2018-May 2020) to identify IPDMAs of test accuracy and prediction models, then elicited whether each IPDMA assessed risk of bias of included studies and, if so, how assessments were reported and subsequently incorporated into the IPDMAs.

RESULTS

Forty-nine IPDMAs were included. Nineteen of 27 (70%) test accuracy IPDMAs assessed risk of bias, compared to 5 of 22 (23%) prediction model IPDMAs. Seventeen of 19 (89%) test accuracy IPDMAs used Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2), but no tool was used consistently among prediction model IPDMAs. Of IPDMAs assessing risk of bias, 7 (37%) test accuracy IPDMAs and 1 (20%) prediction model IPDMA provided details on the information sources (e.g., the original manuscript, IPD, primary investigators) used to inform judgments, and 4 (21%) test accuracy IPDMAs and 1 (20%) prediction model IPDMA provided information or whether assessments were done before or after obtaining the IPD of the included studies or datasets. Of all included IPDMAs, only seven test accuracy IPDMAs (26%) and one prediction model IPDMA (5%) incorporated risk of bias assessments into their meta-analyses. For future IPDMA projects, we provide guidance on how to adapt tools such as Prediction model Risk Of Bias ASsessment Tool (for prediction models) and QUADAS-2 (for test accuracy) to assess risk of bias of included primary studies and their IPD.

CONCLUSION

Risk of bias assessments and their reporting need to be improved in IPDMAs of test accuracy and, especially, prediction model studies. Using recommended tools, both before and after IPD are obtained, will address this.

Prevalence of plantar ulcer and its risk factors in leprosy: a systematic review and meta-analysis

BACKGROUND

Plantar ulcers are a leading complication of leprosy that requires frequent visits to hospital and is associated with stigma. The extent of burden of ulcers in leprosy and its risk factors are scant impeding the development of targeted interventions to prevent and promote healing of ulcers. The aim of this review is to generate evidence on the prevalence of plantar ulcer and its risk factors in leprosy.

METHODS

Databases (Medline, Embase, Web of Science, CINAHL, BVS), conference abstracts and reference lists were searched for eligible studies. Studies were included that reported a point prevalence of plantar ulcer and/or its "risk factors" associated with development of ulcers (either causatively or predictively), including individual level, disease related and bio-mechanical factors. We followed PRISMA guidelines for this review. Random-effects meta-analysis was undertaken to estimate the pooled point prevalence of ulcers. Reported risk factors in included studies were narratively synthesised. This review is registered in PROSPERO: CRD42022316726.

RESULTS

Overall, 15 studies (8 for prevalence of ulcer and 7 for risk factors) met the inclusion criteria. The pooled point prevalence of ulcer was 34% (95% CIs: 21%, 46%) and 7% (95% CIs: 4%, 11%) among those with foot anaesthesia and among all people affected by leprosy, respectively. Risk factors for developing ulcers included: unable to feel 10 g of monofilament on sensory testing, pronated/hyper-pronated foot, foot with peak plantar pressure, foot with severe deformities, and those with lower education and the unemployed.

CONCLUSIONS

The prevalence of plantar ulceration in leprosy is as high as 34% among those with loss of sensation in the feet. However, the incidence and recurrence rates of ulceration are least reported. The inability to feel 10 g of monofilament appears to be a strong predictor of those at risk of developing ulcers. However, there is a paucity of evidence on identifying those at risk of developing plantar ulcers in leprosy. Prospective studies are needed to estimate the incidence of ulcers. Identifying individuals at risk of ulcers will help design targeted interventions to minimize risk factors, prevent ulcers and promote ulcer healing.

Predicting diabetic foot ulceration using routinely collected data in a foot clinic. What level of prognostic accuracy can be achieved?

This study aimed to investigate the efficacy of using routinely collected clinical data in predicting the risk of diabetic foot ulcer (DFU). The first objective was to develop a prognostic model based on the most important risk factors objectively selected from a set of 39 clinical measures. The second objective was to compare the prediction accuracy of the developed model against that of a model based on only the 3 risk factors that were suggested in the systematic review and meta-analyses study (PODUS). In a cohort study, a set of 12 continuous and 27 categorical data from patients (n = 203 M/F:99/104) who attended a specialised diabetic foot clinic were collected at baseline. These patients were then followed-up for 24 months during which 24 (M/F:17/7) patients had DFU. Multivariate logistic regression was used to develop a prognostic model using the identified risk factors that achieved p < 0.2 based on univariate logistic regression. The final prognostic model included 4 risk factors (Adjusted-OR [95% CI]; p) in total. Impaired sensation (116.082 [12.06-1117.287]; p = 0.000) and presence of callus (6.257 [1.312-29.836]; p = 0.021) were significant (p < 0.05), while having dry skin (5.497 [0.866-34.89]; p = 0.071) and Onychomycosis (6.386 [0.856-47.670]; p = 0.071) that stayed in the model were not significant. The accuracy of the model with these 4 risk factors was 92.3%, where sensitivity and specificity were 78.9%, and 94.0% respectively. The 78.9% sensitivity of our prognostic 4-risk factor model was superior to the 50% sensitivity that was achieved when the three risk factors proposed by PODUS were used. Also our proposed model based on the above 4 risk factors showed to predict the DFU with higher overall prognostic accuracy. These findings have implications for developing prognostic models and clinical prediction rules in specific patient populations to more accurately predict DFU.

Correlation of leg pain responses with ankle-brachial index and peripheral sensory responses in foot of type 2 diabetes mellitus

Introduction: Type 2 Diabetes Mellitus (T2DM) is associated with changes that occur in the peripheral circulation that affect foot functions. Therefore, there is a need for a risk prediction test on foot abnormalities using the leg pain response parameters in T2DM patients with ankle-brachial index (ABI) and peripheral sensory changes as a preventive effort to manage foot care. Design and Methods: This study employed a cross-sectional design in which 63 T2DM patients in a Public Health Center (PHC) in Malang were investigated. The instruments used include visual analog scale (VAS), monofilament, and foot doppler. Results: The Pearson correlation test showed no relationship between the responses to leg pain and the ABI of the right and left feet (p-values = 0.217 and 0.692), but there was a significant relationship between the left foot ABI and sensory status (p-value 0.002; left foot r = 0.383). Meanwhile, the Pearson's correlation and linear regression test also showed a relationship between the right foot ABI and sensory status (p-value = 0.007; r = 0.338). Furthermore, a multiple linear regression test showed a relationship between the leg pain response and sensory perception of the right and left feet (p-value = 0.035; r = 0.325). Conclusions: The relationship between the sensory status of the right and left feet and the response to leg pain in T2DM patients were moderate with a negative direction. It, therefore, implies that a decrease in the sensory responses increased the leg pain. Meanwhile, the moderate relationship and positive direction between the ABI and sensory status of the feet of T2DM patients indicates that a higher ABI score led to an increase in the sensory status of the foot.

Distal Metatarsal Osteotomies for Chronic Plantar Diabetic Foot Ulcers

In more than 30 years of scientific literature (1986-2021), the few published studies on the management of CPDFUs by DMOs showed satisfactory clinical and radiographic outcomes. Although these reports were all case series, their data suggest that DMOs, performed at a different level of the distal metatarsal bones, are an effective surgical treatment option for achieving rapid healing of CPDFUs and preventing their recurrence after balancing the pressures in diabetic forefeet. Hence, DMOs can be a valid alternative treatment method also for CPDFUs with chronic infection, ulcers penetrating deep structures, and even ulcers with osteomyelitis at the metatarsophalangeal level.

Resource use within a multidisciplinary foot team clinic

OBJECTIVE

The establishment of multidisciplinary foot team clinics reduces the risk of amputation, but little is known about its resource requirement. This study evaluates the service's resource use for first visit attendees to an established multidisciplinary foot team clinic.

METHOD

A retrospective evaluation was performed for new referrals to the clinic over six months, including demographics, resource use and clinical outcome. Data were extracted electronically with retrospective review of electronic clinical notes.

RESULTS

A total of 240 first visit attendees were analysed. Mean age was 64±15years, 63% were male, 72% had type 2 diabetes, 16% had type 1 diabetes, 15% had a previous amputation, and 40% had a previous ulceration. Common presentations were ulcers (62%), osteomyelitis (11%), Charcot foot (19%), foot ischaemia (17%), post-surgical wounds (13%), and osteomyelitis (11%). At first attendance, 79% of patients required specialist services including diabetologist (45%), joint vascular review (23%), joint orthopaedics services (8%), dermatologist (2%), and orthotics services (1%). A total of 4% of patients had complex debridement, 0.4% total nail excision, 0.8% pus drainage, 3% cast-related procedures, and 1% vacuum-assisted dressing. Of the patients, 4% were admitted to hospital, 38% had vascular duplex investigations, 7% had a deep vein thrombosis scan, 16% had magnetic resonance imagine (MRI), and 5% had a bone scan.

CONCLUSION

A functional multidisciplinary foot team clinic requires significant resources-both clinical and administrative-for prompt investigations and revascularisation to sustain low amputation rates. Regular appraisal of resource use helps with clinic and pathway planning.

Predictors and outcomes of diabetic foot ulcer infection with ESBL-producing bacteria in a large tertiary center

OBJECTIVES

The aim of this study was to describe the predictors and outcomes of infection with extended-spectrum beta-lactamase (ESBL)-producing bacteria in patients with an acute diabetic foot infection (DFI).

METHODS

The records of patients admitted with acute DFI to a large tertiary hospital during the years 2014-2018 were reviewed. Demographic, clinical, and laboratory data were collected, as well as outcomes regarding amputations and mortality. Only cultures obtained during the first 2 weeks following admission were considered.

RESULTS

Cultures were available for 493 patients; 121 (24.5%) included bacteria suspected of being ESBL producers. Patients infected with ESBL-producing bacteria were older, more likely to have peripheral vascular disease (PVD), and had higher SINBAD and Wagner scores upon admission. They were also more likely to have been hospitalized in the recent 6 months. Major amputations were more prevalent in patients with versus without an ESBL-producing bacterial infection (30.6% vs 19.4%; P = 0.010), yet overall amputations and mortality rates were similar.

CONCLUSIONS

ESBL-producing bacteria are common pathogens in DFI, more prevalent in older patients with PVD, advanced ulcers, and recent hospitalization. They are associated with higher rates of major amputation. These considerations may support the choice of empirical antibiotic therapy in patients admitted with an acute DFI.

Prognostic models for predicting the risk of foot ulcer or amputation in people with type 2 diabetes: a systematic review and external validation study

AIMS/HYPOTHESIS

Approximately 25% of people with type 2 diabetes experience a foot ulcer and their risk of amputation is 10-20 times higher than that of people without type 2 diabetes. Prognostic models can aid in targeted monitoring but an overview of their performance is lacking. This study aimed to systematically review prognostic models for the risk of foot ulcer or amputation and quantify their predictive performance in an independent cohort.

METHODS

A systematic review identified studies developing prognostic models for foot ulcer or amputation over minimal 1 year follow-up applicable to people with type 2 diabetes. After data extraction and risk of bias assessment (both in duplicate), selected models were externally validated in a prospective cohort with a 5 year follow-up in terms of discrimination (C statistics) and calibration (calibration plots).

RESULTS

We identified 21 studies with 34 models predicting polyneuropathy, foot ulcer or amputation. Eleven models were validated in 7624 participants, of whom 485 developed an ulcer and 70 underwent amputation. The models for foot ulcer showed C statistics (95% CI) ranging from 0.54 (0.54, 0.54) to 0.81 (0.75, 0.86) and models for amputation showed C statistics (95% CI) ranging from 0.63 (0.55, 0.71) to 0.86 (0.78, 0.94). Most models underestimated the ulcer or amputation risk in the highest risk quintiles. Three models performed well to predict a combined endpoint of amputation and foot ulcer (C statistics >0.75).

CONCLUSIONS/INTERPRETATION

Thirty-four prognostic models for the risk of foot ulcer or amputation were identified. Although the performance of the models varied considerably, three models performed well to predict foot ulcer or amputation and may be applicable to clinical practice.

Development of a prediction model for foot ulcer recurrence in people with diabetes using easy-to-obtain clinical variables

INTRODUCTION

We aimed to develop a prediction model for foot ulcer recurrence in people with diabetes using easy-to-obtain clinical variables and to validate its predictive performance in order to help risk assessment in this high-risk group.

RESEARCH DESIGN AND METHODS

We used data from a prospective analysis of 304 people with foot ulcer history who had 18-month follow-up for ulcer outcome. Demographic, disease-related and organization-of-care variables were included as potential predictors. Two logistic regression prediction models were created: model 1 for all recurrent foot ulcers (n=126 events) and model 2 for recurrent plantar foot ulcers (n=70 events). We used 10-fold cross-validation, each including five multiple imputation sets for internal validation. Performance was assessed in terms of discrimination using area under the receiver operating characteristic curve (AUC) (0-1, 1=perfect discrimination), and calibration with the Brier Score (0-1, 0=complete concordance predicted vs observed values) and calibration graphs.

RESULTS

Predictors in model 1 were: a younger age, more severe peripheral sensory neuropathy, fewer months since healing of previous ulcer, presence of a minor lesion, use of a walking aid and not monitoring foot temperatures at home. Mean AUC for model 1 was 0.69 (2SD 0.040) and mean Brier Score was 0.22 (2SD 0.011). Predictors in model 2 were: a younger age, plantar location of previous ulcer, fewer months since healing of previous ulcer, presence of a minor lesion, consumption of alcohol, use of a walking aid, and foot care received in a university medical center. Mean AUC for model 2 was 0.66 (2SD 0.023) and mean Brier Score was 0.16 (2SD 0.0048).

CONCLUSIONS

These internally validated prediction models predict with reasonable to good calibration and fair discrimination who is at highest risk of ulcer recurrence. The people at highest risk should be monitored more carefully and treated more intensively than others.

TRIAL REGISTRATION NUMBER

NTR5403.

Development and validation of a clinical prediction rule for development of diabetic foot ulceration: an analysis of data from five cohort studies

INTRODUCTION

The aim of the study was to develop and validate a clinical prediction rule (CPR) for foot ulceration in people with diabetes.

RESEARCH DESIGN AND METHODS

Development of a CPR using individual participant data from four international cohort studies identified by systematic review, with validation in a fifth study. Development cohorts were from primary and secondary care foot clinics in Europe and the USA (n=8255, adults over 18 years old, with diabetes, ulcer free at recruitment). Using data from monofilament testing, presence/absence of pulses, and participant history of previous ulcer and/or amputation, we developed a simple CPR to predict who will develop a foot ulcer within 2 years of initial assessment and validated it in a fifth study (n=3324). The CPR's performance was assessed with C-statistics, calibration slopes, calibration-in-the-large, and a net benefit analysis.

RESULTS

CPR scores of 0, 1, 2, 3, and 4 had a risk of ulcer within 2 years of 2.4% (95% CI 1.5% to 3.9%), 6.0% (95% CI 3.5% to 9.5%), 14.0% (95% CI 8.5% to 21.3%), 29.2% (95% CI 19.2% to 41.0%), and 51.1% (95% CI 37.9% to 64.1%), respectively. In the validation dataset, calibration-in-the-large was -0.374 (95% CI -0.561 to -0.187) and calibration slope 1.139 (95% CI 0.994 to 1.283). The C-statistic was 0.829 (95% CI 0.790 to 0.868). The net benefit analysis suggested that people with a CPR score of 1 or more (risk of ulceration 6.0% or more) should be referred for treatment.

CONCLUSION

The clinical prediction rule is simple, using routinely obtained data, and could help prevent foot ulcers by redirecting care to patients with scores of 1 or above. It has been validated in a community setting, and requires further validation in secondary care settings.

Complication rate among people with diabetes at low risk of foot ulceration in Fife, UK: an analysis of routinely collected data

AIMS

To estimate the rate at which people with diabetes and a low risk of foot ulceration change diabetic foot ulceration risk status over time, and to estimate the rate of ulceration, amputation and death among this population.

METHODS

We conducted an observational study of 10 421 people with diabetes attending foot screening in an outpatient setting in NHS Fife, UK, using routinely collected data from a national diabetes register, NHS SCI Diabetes. We estimated the proportion of people who changed risk status and the cumulative incidence of ulceration, amputation and death, respectively, among people with diabetes at low risk of diabetic foot ulceration at 2-year follow-up.

RESULTS

At 2-year follow-up, 5.1% (95% CI 4.7, 5.6) of people with diabetes classified as low risk at their first visit had progressed to moderate risk. The cumulative incidence of ulceration, amputation and death was 0.4% (95% CI 0.3, 0.6), 0.1% (95% CI 0.1, 0.2) and 3.4% (95% CI 3.1, 3.8), respectively.

CONCLUSIONS

At 2-year follow-up, 5% of people at low risk of diabetic foot ulceration changed clinical risk status and <1% of people experienced foot ulceration or amputation. These findings provide information which will help to inform the current debate regarding optimal foot screening intervals.

Competitive neural layer-based method to identify people with high risk for diabetic foot

BACKGROUND AND OBJECTIVE

To automatically identify patients with diabetes mellitus (DM) who have high risk of developing diabetic foot, via an unsupervised machine learning technique.

METHODS

We collected a new database containing 54 known risk factors from 250 patients diagnosed with diabetes mellitus. The database also contained a separate validation cohort composed of 73 subjects, where the perceived risk was annotated by expert nurses. A competitive neuron layer-based method was used to automatically split training data into two risk groups.

RESULTS

We found that one of the groups was composed of patients with higher risk of developing diabetic foot. The dominant variables that described group membership via our method agreed with the findings from other studies, and indicated a greater risk for developing such a condition. Our method was validated on the available test data, reaching 71% sensitivity, 100% specificity, and 90% accuracy.

CONCLUSIONS

Unsupervised learning may be deployed to screen patients with diabetes mellitus, pointing out high-risk individuals who require priority follow-up in the prevention of diabetic foot with very high accuracy. The proposed method is automatic and does not require clinical examinations to perform risk assessment, being solely based on the information of a questionnaire answered by patients. Our study found that discriminant variables for predicting risk group membership are highly correlated with expert opinion.

Predicting the risk of future diabetic foot ulcer occurrence: a prospective cohort study of patients with diabetes in Tanzania

OBJECTIVES

The aim of this study was to identify the parameters that predict the risk of future foot ulcer occurrence in patients with diabetes.

RESEARCH DESIGN AND METHODS

1810 (male (M)/female (F): 1012/798) patients, with no foot ulcer at baseline, participated in this study. Data from a set of 28 parameters were collected at baseline. During follow-up, 123 (M/F: 68/55) patients ulcerated. Survival analyses together with logistic regression were used to identify the parameters that could predict the risk of future diabetic foot ulcer occurrence.

RESULTS

A number of parameters (HR (95% CI)) including neuropathy (2.525 (1.680 to 3.795)); history of ulceration (2.796 (1.029 to 7.598)); smoking history (1.686 (1.097 to 2.592)); presence of callus (1.474 (0.999 to 2.174)); nail ingrowth (5.653 (2.078 to 15.379)); foot swelling (3.345 (1.799 to 6.218)); dry skin (1.926 (1.273 to 2.914)); limited ankle (1.662 (1.365 to 2.022)) and metatarsophalangeal (MTP) joint (2.745 (1.853 to 4.067)) ranges of motion; and decreased (3.141 (2.102 to 4.693)), highly decreased (5.263 (1.266 to 21.878)), and absent (9.671 (5.179 to 18.059)) sensation to touch; age (1.026 (1.010 to 1.042)); vibration perception threshold (1.079 (1.060 to 1.099)); duration of diabetes (1.000 (1.000 to 1.000)); and plantar pressure at the first metatarsal head (1.003 (1.001 to 1.005)), temperature sensation (1.019 (1.004 to 1.035)) and temperature tolerance (1.523 (1.337 to 1.734)) thresholds to hot stimuli and blood sugar level (1.027 (1.006 to 1.048)) were all significantly associated with increased risk of ulceration. However, plantar pressure underneath the fifth toe (0.990 (0.983 to 0.998)) and temperature sensation (0.755 (0.688 to 0.829)) and temperature tolerance (0.668 (0.592 to 0.0754)) thresholds to cold stimuli showed to significantly decrease the risk of future ulcer occurrence. Multivariate survival model indicated that nail ingrowth (4.42 (1.38 to 14.07)); vibration perception threshold (1.07 (1.04 to 1.09)); dry skin status (4.48 (1.80 to 11.14)); and temperature tolerance threshold to warm stimuli (1.001 (1.000 to 1.002)) were significant predictors of foot ulceration risk in the final model. The mean time to ulceration was significantly (p<0.05) shorter for patients with: dry skin (χ²=11.015), nail ingrowth (χ²=14.688), neuropathy (χ²=21.284), or foot swelling (χ²=16.428).

CONCLUSION

Nail ingrowth and dry skin were found to be strong indicators of vulnerability of patients to diabetic foot ulceration. Results highlight that assessments of neuropathy in relation to both small and larger fiber impairment need to be considered for predicting the risk of diabetic foot ulceration.

Preventing foot ulceration in diabetes: systematic review and meta-analyses of RCT data

AIMS/HYPOTHESIS

Foot ulceration is a serious complication for people with diabetes that results in high levels of morbidity for individuals and significant costs for health and social care systems. Nineteen systematic reviews of preventative interventions have been published, but none provides a reliable numerical summary of treatment effects. The aim of this study was to systematically review the evidence from RCTs and, where possible, conduct meta-analyses to make the best possible use of the currently available data.

METHODS

We conducted a systematic review and meta-analysis of RCTs of preventative interventions for foot ulceration. OVID MEDLINE and EMBASE were searched to February 2019 and the Cochrane Central Register of Controlled Trials to October 2018. RCTs of interventions to prevent foot ulcers in people with diabetes who were free from foot ulceration at trial entry were included. Two independent reviewers read the full-text articles and extracted data. The quality of trial reporting was assessed using the Cochrane Risk of Bias tool. The primary outcome of foot ulceration was summarised using pooled relative risks in meta-analyses.

RESULTS

Twenty-two RCTs of eight interventions were eligible for analysis. One trial of digital silicone devices (RR 0.07 [95% CI 0.01, 0.55]) and meta-analyses of dermal infrared thermometry (RR 0.41 [95% CI 0.19, 0.86]), complex interventions (RR 0.59 [95% CI 0.38, 0.90], and custom-made footwear and offloading insoles (RR 0.53 [95% CI 0.33, 0.85]) showed beneficial effects for these interventions.

CONCLUSIONS/INTERPRETATION

Four interventions were identified as being effective in preventing foot ulcers in people with diabetes, but uncertainty remains about what works and who is most likely to benefit.

Diabetic foot ulcer incidence and survival with improved diabetic foot services: an 18-year study

AIMS

To ascertain the effects of improvements in diabetic foot services over 18 years on incidence of diabetic foot ulceration. We also compared survival time from first ulcer development with presence of neuropathy, peripheral vascular disease, age and healing.

METHODS

Persons with new ulceration and those at high risk of ulcer development were referred to community podiatry from 1998. Their details were recorded, with verbal consent, on a central database. The effects of neuropathy, peripheral vascular disease, healing and age on survival were analysed by Cox proportional hazards ratios.

RESULTS

The incidence of first ulcer presentation decreased from 11.1 to 6.1 per 1000 persons between 2003 to 2017 (P <0.0001). Recurrent ulceration incidence remained stable. Prevalence of chronic and new foot ulceration combined increased from 20.7 to 33.1 per 1000 persons (P <0.0001). Ten-year survival was 85% for persons presenting with first ulcer and aged < 65 years, 50% for those aged 65-74 years and 25% for those aged 75-81 years (P < 0.0001). In those with peripheral vascular disease 5-year survival was 35% (P <0.001).

CONCLUSIONS

Integrated care for the diabetic foot in one National Health Service (NHS) health service area over 18 years was associated with a reduction in first presentations of diabetic foot ulceration, but failed to reduce recurrent ulceration. Cumulative prevalence of all ulcers continues to increase. Monitoring ulceration incidence can inform audit and planning of diabetic foot care services. Survival is better than reported previously in persons < 65 years and in the absence of peripheral vascular disease.

Incidence and predictors of recurrent and other new diabetic foot ulcers: a retrospective cohort study

AIMS

To estimate progression rates, evaluate risk factors for progression, and study rate ratios for progression among people with a healed diabetic foot ulcer according to whether the healed ulcer was neuropathic, neuro-ischaemic or critically ischaemic.

METHODS

We conducted a retrospective cohort study in all individuals with a healed diabetic foot ulcer treated at the Steno Diabetes Centre Copenhagen foot clinic in the period 2010 to 2016. The outcome of interest was recurrent/other new diabetic foot ulcers.

RESULTS

A total of 780 people had a healed diabetic foot ulcer in the study period (2010-2016). The participants were followed for 1249 person-years [median (Q1-Q3) 1.04 (0.38-2.46) person-years] in total. One-third (33.1%) developed a recurrent/other new diabetic foot ulcer per year. Male gender, people with Type 2 diabetes and smokers had a statistically significantly higher risk of progression to a recurrent/other new diabetic foot ulcer compared to participants without these risk factors. Participants with neuro-ischaemic or critically ischaemic diabetic foot ulcers had statistically significantly higher progression rates than participants with neuropathic diabetic foot ulcers.

CONCLUSIONS

Focus should be on preventing future recurrent/other new diabetic foot ulcers especially in people with ischaemia.

Innovative intelligent insole system reduces diabetic foot ulcer recurrence at plantar sites: a prospective, randomised, proof-of-concept study

BACKGROUND

Prevention of diabetic foot ulcer recurrence in high risk patients, using current standard of care methods, remains a challenge. We hypothesised that an innovative intelligent insole system would be effective in reducing diabetic foot ulcer recurrence in such patients.

METHODS

In this prospective, randomised, proof-of-concept study, patients with diabetes, and with peripheral neuropathy and a recent history of plantar foot ulceration were recruited from two multidisciplinary outpatient diabetic foot clinics in the UK, and were randomly assigned to either intervention or control. All patients received an insole system, which measured plantar pressure continuously during daily life. The intervention group received audiovisual alerts via a smartwatch linked to the insole system and offloading instructions when aberrant pressures were detected; the control group did not receive any alerts. The primary outcome was plantar foot ulcer occurrence within 18 months. This trial is registered with ISRCTN, ISRCTN05585501, and is closed to accrual and complete.

FINDINGS

Between March 18, 2014, and Dec 20, 2016, 90 patients were recruited and consented to the study, and 58 completed the study. At follow-up, ten ulcers from 8638 person-days were recorded in the control group and four ulcers from 11 835 person-days in the intervention group: a 71% reduction in ulcer incidence in the intervention group compared with the control group (incidence rate ratio 0·29, 95% CI, 0·09-0·93; p=0·037). The number of patients who ulcerated was similar between groups (six of 26 [control group] vs four of 32 [intervention group]; p=0·29); however, individual plantar sites ulcerated more often in the control group (ten of 416) than in the intervention group (four of 512; p=0·047). In an exploratory analysis of good compliers (n=40), ulcer incidence was reduced by 86% in the intervention group versus control group (incidence rate ratio 0·14, 95% CI 0·03-0·63; p=0·011). In the exploratory analysis, plantar callus severity (change from baseline to 6 months) was greater in re-ulcerating patients (6·5, IQR 4·0-8·3) than non-re-ulcerating patients (2·0, 0·0-4·8; p=0·040).

INTERPRETATION

To our knowledge, this study is the first to show that continuous plantar pressure monitoring and dynamic offloading guidance, provided by an innovative intelligent insole system, can lead to a reduction in diabetic foot ulcer site recurrence.

FUNDING

Diabetes UK and Orpyx Medical Technologies.

Standard complication screening information can be used for risk assessment for first time foot ulcer among patients with type 1 and type 2 diabetes

AIM

Diabetic foot ulcer (DFU) is a major complication of both Type 1 Diabetes (T1D) and Type 2 Diabetes (T2D); however research into risk factors for DFU does not separate between these two types. The purpose of the present investigation was to identify risk factors for development of first time DFU (FTDFU) over a period of 15 years in patients with T1D and T2D separately.

METHODS

This retrospective cohort study included 25,220 feet from 5588 patients with T1D and 7113 patients with T2D treated in the period 2001-2015. Data on baseline characteristics and comorbidities were collected from electronic patient records. Influences of various risk factors for the development of FTDFU were assessed by hazard ratios (HR) from Cox proportional hazard regression models on time from enrolment to FTDFU diagnosis or end-of-follow-up.

RESULTS

In T1D independent risk factors were male sex, age >60 years, high HbA1c, long diabetes duration, history of cardiovascular disease, macro-albuminuria, decreased visual acuity, advanced diabetic retinopathy, decreased/absent vibration sense, presence of patient reported symptoms of neuropathy, and absence of foot pulses. In T2D the independent risk factors were the same except age >60 years, a history of cardiovascular disease, and long diabetes duration.

CONCLUSIONS

This study documents that much of the standard clinical information obtained as part of the routine follow-up are also independent risk factors for development of FTDFU. This may be used to create a basis for in which patient and when prevention should be started.