Measurements of success in diabetic foot care

Health care targets currently focus on reduction in the incidence of amputation, while the majority of trials into new treatments use healing. Although conceptually simple, both measures require careful definition. Moreover, each contains an implicit assumption: that their achievement is synonymous with good care, with success. This is not always the case, and the endpoints for future prospective research and audit must be chosen with precision. The first principle to be embraced is that of population selection – since the results of research and audit should usually be generalisable, and this is not possible unless the population is carefully characterized in terms of people (race, age, diabetes control, co-morbidities etc), limb (ischaemia, neuropathy, deformity) and ulcer (duration, area, depth, infection etc). The second issue relates to trial design: is the study one to determine efficacy  (“can it work ?”), efficiency (“does it work ?”) or effectiveness (“how well does it work ?). Chosen endpoints are also governed by the type of intervention being studied: reduction of ulcer area might be an appropriate measure of the efficacy of a wound care product, or peripheral limb TcpO₂ for a revascularisation procedure. But studies of efficiency and effectiveness should be more patient-centered and include measures of well-being and satisfaction. Studies of antibiotics pose special problems and yet they are still desperately needed to answer many unanswered questions on choice, route, duration and role vis à vis surgery. The difficulty with antibiotic trials relates to the fact that their role is to eradicate infection (and not necessarily to heal ulcers, or to save limbs) – and yet both infection and its eradication are very difficult to define, either clinically or microbiologically. In evaluating antibiotic regimens, the best approach may be to compare costs, adverse events and patient-centred measures, while assuming therapeutic equivalence.

Abstract for presentation at De diabetische voet, Almelo, The Netherlands, January 2004