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

Aims Diabetes guidelines recommend screening for the risk of foot ulceration but vary substantially in the underlying evidence base. Our purpose was to derive and validate a prognostic model of independent risk factors for foot ulceration in diabetes using all available individual patient data from cohort studies conducted worldwide. MethodsResultsWe conducted a systematic review and meta-analysis of individual patient data from 10 cohort studies of risk factors in the prediction of foot ulceration in diabetes. Predictors were selected for plausibility, availability and low heterogeneity. Logistic regression produced adjusted odds ratios (ORs) for foot ulceration by ulceration history, monofilament insensitivity, any absent pedal pulse, age, sex and diabetes duration. The 10 studies contained data from 16385 participants. A history of foot ulceration produced the largest OR [6.59 (95% CI 2.49 to 17.45)], insensitivity to a 10g monofilament [3.18 (95% CI 2.65 to 3.82)] and any absent pedal pulse [1.97 (95% CI 1.62 to 2.39)] were consistently, independently predictive. Combining three predictors produced sensitivities between 90.0% (95% CI 69.9% to 97.2%) and 95.3% (95% CI 84.5% to 98.7%); the corresponding specificities were between 12.1% (95% CI 8.2% to 17.3%) and 63.9% (95% CI 61.1% to 66.6%). ConclusionsWhat's new?This prognostic model of only three risk factors, a history of foot ulceration, an inability to feel a 10g monofilament and the absence of any pedal pulse, compares favourably with more complex approaches to foot risk assessment recommended in clinical diabetes guidelines. Cohort studies to identify risk factors for foot ulceration in people with diabetes have been published in the biomedical literature since the early 1990s. We assembled an international data set of risk factors collected from 16385 individuals with diabetes who took part in cohort studies to derive and validate a prognostic model of three risk factors: a history of foot ulceration, an inability to feel a 10g monofilament and at least one absent pedal pulse. The use of only these three risk factors in foot risk assessments during annual diabetes foot checks could reduce the amount of time spent assessing risk and thereby increase the number of people with diabetes who have checks performed. The frequency of risk assessment should be considered in future research.