Introduction
Diabetic foot disease is a common complication of both type 1 and type 2 diabetes. The impact of diabetic foot disease is substantial; patients with diabetes developing foot ulcers have a low quality of life and treatment is often long and intensive [
1]. In view of the increasing number of diabetic patients and limited healthcare resources, data on the cost of treatment are necessary to prioritise healthcare expenditures and to attempt to determine which patients and aspects of treatment are the most important determinants of costs. Although only a minority of foot ulcers will result in a lower extremity amputation (LEA) [
2], these amputations are associated with the highest costs. Studies from Sweden have demonstrated that the cost of treatment for a patient who healed after an amputation were about €29,000–43,000 in the 1990s, depending on the amputation level and whether or not the foot ulcer was infected [
3‐
5]. A recent paper on a prospective Australian study reported that, on average, inpatient costs for LEA totalled AU$17,089 [
6].
Several retrospective single-centre studies, using different methodologies, have found that costs for foot ulcer treatment in general are also high [
7‐
10]. The pathophysiology of diabetic foot disease is complex, and because several factors may play a role in the development of foot ulcers, the population of individuals presenting with diabetic foot ulcers is relatively heterogeneous. For instance, in a recently published paper by the European Study Group on Diabetes and the Lower Extremity (Eurodiale), in which patients were grouped according to the presence or absence of peripheral arterial disease (PAD) and/or infection, individuals with both PAD and infection were older, more often had severe comorbidity and frequently had larger ulcers at presentation, most of which were non-plantar [
11]. Many of these factors also predicted non-healing [
2], and poor healing is likely to be associated with high resource utilisation. Because the characteristics of patients who are treated in different diabetic foot units may vary, it is important to obtain prospective data on resource utilisation and associated costs in relation to specific patient characteristics. To put the cost of treatment into perspective, outcome data should also be taken into account.
The Eurodiale Study was a prospective, multicentre, observational study on patients with a diabetic foot ulcer. The design, baseline patient characteristics and clinical outcomes have been published elsewhere [
2,
11,
12]. This project was also designed as a cost of treatment study, and its aim was to analyse resource utilisation and associated costs in a large cohort of well-characterised patients with diabetic foot ulcers and to determine the differences in resource utilisation between individuals with or without PAD and/or infection.
Methods
Study design and population
The Eurodiale consortium is a collaborative network of 14 European diabetic foot centres, created to stimulate research in the field of diabetic foot disease. The design and rationale of this study have been described in detail elsewhere [
12]. Briefly, between 1 September 2003 and 1 October 2004, patients presenting with a new foot ulcer at 14 diabetic foot centres in ten European countries enrolled in the study. A total of 1,232 patients with a new foot ulcer were enrolled into the study and 1,088 were followed until endpoint.
Subjects attended follow-up visits on a monthly basis until an endpoint or study end was reached. The endpoints were healing of the complete foot, major amputation and death. Definitions of the baseline characteristics have been published previously and are based on the Perfusion, Extent/size, Depth/tissue loss, Infection and Sensation (PEDIS) classification system [
12,
13]. For the costing analysis, patients were grouped according to disease severity, as indicated by the presence or absence of PAD and/or infection (stages of the University of Texas wound classification system [
14]). The main characteristics of all patients available for evaluation are presented in Table
1.
Table 1
Patient characteristics at inclusion
Age (years)a
| 65 (24–95) |
Sex |
Male | 704 (65) |
Female | 384 (35) |
Ulcer duration at inclusion |
<1 week | 184 (17) |
<3 months | 625 (57) |
>3 months | 269 (25) |
Ulcer size at inclusion | |
<1.0 cm2
| 403 (37) |
1.0–5.0 cm2
| 561 (52) |
>5.0 cm2
| 117 (11) |
Depth of ulcer at inclusion |
Superficial ulcer | 612 (56) |
Deep ulcer | 476 (44) |
Comorbidity |
Heart failure NYHA III–IV | 117 (11) |
Inability to stand or walk without help | 107 (10) |
Neurological disorder | 70 (6) |
Visual impairment | 164 (15) |
End-stage renal disease | 63 (6) |
The study was approved by local ethics committees in all countries and all participants gave written informed consent.
Unit cost data
Costing consists of two elements: measurement of the resources used and the assignment of unit costs. In the present study the analysis of resource utilisation for the management of patients with diabetic foot ulcers is based on the study data for all patients followed up to endpoint who were available for analysis (n = 1,088).
Given the high variability in underlying pathology and disease severity, only countries with at least 80 patients available for analysis were included in the cost analysis, to ensure that the data were reliable and representative. In addition, countries for which complete information about unit costs for every type of resource used could not be provided were excluded from the cost analysis.
For each country, unit cost data were collected from official pricelists or other national sources. The unit costs should, as far as possible, reflect the ‘true’ resource utilisation in each country. Therefore, the unit cost of a procedure, a drug or a visit to the clinic included the total cost, irrespective of who was responsible for paying all or part of the costs. The payer could be the patient, the hospital, an authority, an insurance company, or a combination.
The unit costs of all types of resources used in the management of diabetic foot ulcers were provided by participating centres from seven (Czech Republic, Denmark, Italy, the Netherlands, Slovenia, Sweden and the UK) of the ten participating countries, using a specific unit cost form. In total, 75% of the patients available for analysis (n = 821) were included in the economic analysis.
The unit cost form was based on the items listed in the entry and follow-up forms of the Eurodiale Study [
12]. It contained questions about local currency, year of cost data, unit costs for inpatient and outpatient care, investigations, interventions, antibiotics, different types of staff, topical dressings, transport and the income of the general population. For each type of resource it was possible to include additional comments, e.g. if any unit cost referred to a year different from the majority of the other unit costs. In addition, the sources of the unit costs were given.
Cost calculation
Costs were calculated individually for each patient according to the resource utilisation indicated in the entry and follow-up forms. For each country, the utilisation of each type of resource was multiplied by the corresponding unit cost for the resource in that particular country. Costs were calculated from the entry date up to the date of the final visit. Any unrealistic values of resource utilisation have been checked and if necessary recoded to avoid overestimation of resource use and costs.
Discussion
In this study we have collected prospective data on resource use and costs associated with the treatment of diabetic foot ulcers. Costs are high, the average total for direct and indirect cost being approximately €10,000, based on the costing data of 821 patients from the participating countries. Importantly, resource utilisation and costs varied between the different outcome groups and between individuals with and without PAD and/or infection at baseline.
The average costs reported in this study cannot easily be compared with data published in the current literature in view of the differences with respect to included patients, duration of follow-up and methods for analyses. The data may be compared with the single-centre data from Sweden, reported in the early 1990s, in which costs for primary healing of the ulcer were approximately US$8,950 [
15], which is about €7,412 according to 2005 prices. The results reported by an American group, based on medical and pharmaceutical claims data from 2000 and 2001, included both in- and outpatients with and without PAD. The average direct cost per ulcer episode was US$13,179 (approximately €10,914), ranging from US$5,218 (€4,321) in patients with adequate vascular status to US$23,372 (€19,357) in individuals with inadequate vascular status [
16]. In the present European study, costing data are derived from several countries, including both low- and high-cost countries, although costs were weighted by purchasing power standards to compensate for this. These data very clearly demonstrate that treatment of diabetic foot disease is a major determinant of diabetes-related resource utilisation and costs throughout Europe. Based on the data for Europe for 2003, which showed a prevalence of diabetes of 48 million people and an ulcer incidence among diabetic patients of 2% per year [
1], the costs associated with the treatment of diabetic foot ulcers may be as high as ten billion Euros per year.
It is clear from the present study that the costs for the treatment of individuals with PAD, especially in combination with infection, are substantially higher than those for the treatment of patients without PAD. Only a small proportion of this difference is attributable to higher costs for diagnostic procedures. Most of the excess costs in individuals with PAD and infection are related to a higher rate of hospitalisation and higher costs of antibiotics, amputations, revascularisation and other surgery. We have previously demonstrated that characteristics and predictors of outcome are very different in patients with and without PAD, which suggests that these conditions should be regarded as separate disease states [
2]. The resource and cost data reported here support this concept. Habacher et al. [
7] recently published retrospective data on a group of 89 patients from an Austrian tertiary referral hospital in which similar differences between patients with and without PAD and/or infection were observed. They reported costs for the patients with foot ulcers but without PAD and infection of €1,071 vs €7,844 for the patients with both PAD and infection. However, the costs for the latter group were less than 50% of those for the corresponding group in our cohort. This difference may be related to differences in costing between the studies, for example, it is unclear whether staff costs for dressing changes in outpatient care were included in the Austrian study.
In the current study, the majority of costs for the treatment of diabetic foot disease were related to hospital admissions
. In the Eurodiale Study, 27% of the patients were admitted at baseline [
11] and a number of patients were admitted during follow-up. In view of the magnitude of these costs, reducing the number and duration of hospital admissions seems an attractive option for decreasing the costs associated with the treatment of diabetic foot disease. The hospital admissions are usually related to progressive tissue loss in the context of PAD and/or infection. We think that strategies aimed at early referral, timely institution of antibiotic therapy and early vascular intervention may help to prevent progressive tissue loss, thereby reducing admission rates. The development of such strategies should be one of the main priorities in diabetic foot care over the next years.
The costs for lower leg amputations in this study are not completely comparable with those reported by previous studies. One possible explanation for this is that patients who underwent a lower leg amputation in the present study were only followed until this amputation was performed, whereas in previous Swedish studies, patients were followed and costs calculated until the amputated leg was completely healed [
15,
17]. Similarly, the cost of a lower leg amputation reported by the recent Australian study is considerably lower than that reported by the present study, mainly because only inpatient costs were included in their analyses [
6]. Patients included in the present study who underwent minor amputations below the ankle, which subsequently healed, were classified as healed patients, whereas the costs of minor amputations were presented separately in the previous Swedish studies [
15,
17]. The total average costs for patients classified as healed are therefore probably higher than if patients who had undergone a minor amputation had not been included in this group.
In the present study the average costs of antibiotics constituted between 11% and 14% of the total direct costs for patients with infection, despite the fact that some antibiotic use was probably not reported. The number of patients with infection reported to be treated with antibiotics was significantly less than 100%. These costs are much higher than those reported by a Swedish study in which the share of costs for antibiotics was 4.5% [
17]. One reason for this discrepancy in costs could be the use of more expensive antibiotics, more parenteral drugs and longer treatment periods across 2003–2004 compared with the early 1990s. Moreover, policies for the prescription of antibiotics can differ substantially between countries, stressing the importance of performing multinational studies.
One limitation of the study is that unit cost data could not be calculated for all participating countries because of the lower number of patients enrolled and difficulties in obtaining data on certain resources in some countries. Cost calculations were possible for seven of the ten countries or 75% of the patients included. Difficulties in collecting reliable unit costs have previously been described and should not be neglected when planning health-economic studies [
18]. These difficulties also indicate the importance of reporting resource utilisation in terms of physical quantities (e.g. two dressings, two bypasses). Another limitation is that the analyses of resource utilisation and costs do not include the total resources used for the management of diabetic foot disease because patients could have been treated for their present foot ulcer at a different centre before being included in the study. Thus, the actual values for resource use and costs are probably higher than reported in this article, but, in general, it is too difficult to accurately obtain information on treatment retrospectively. The study is also limited by the fact that recurrent ulcers were excluded, and that a proportion of the cohort (although less than a third) were tertiary referrals to specialised centres, which may treat more complex patients
. Finally, any cost of treatment study is limited by the incomplete generalisability of economic data or transferability of results from one country to another [
19]. Treatment costs are, amongst other things, influenced by differences in the availability of healthcare resources and variations in clinical practice, together with differences in incentives given to healthcare professionals. As described elsewhere, we found significant variations in clinical practice between centres. In particular, there were marked differences in the use of resources such as total contact casting and vascular imaging [
20]. In addition, the relative prices and costs may vary between countries. This problem has at least partly been circumvented in the present study by the conversion of local costs into purchasing power standards.
Although the current study is subject to several weaknesses, as described above, a strength was the relatively large cohort monitored prospectively in daily clinical practice until a predefined treatment outcome or study end date was reached, with no predetermined intervention options. Ten European countries participated in the resource use analysis and data from seven countries and ten centres were available for the cost analysis. The perspective of the study was societal, including both direct and indirect costs, irrespective of payers and reimbursement systems in the participating countries. The present information illustrates the magnitude of the problem in economic terms for decision makers both within and outside the healthcare system. Moreover, it can help us to define target groups for whom an improvement in care could result in major savings in healthcare expenditure. Up to now many publications in the field of diabetic foot disease have focused on wound healing in patients with a neuropathic foot ulcer, the group with the lowest costs in our analyses. Although several studies on the treatment of infection have been published, patients with PAD were usually excluded or not specifically analysed in these studies. Our data suggest that to reduce the high costs of diabetic foot disease, major efforts should be undertaken to improve the treatment in this subgroup of patients, who have the highest costs and the poorest outcome.
This health-economic study is mainly descriptive, but the database constructed could be a valuable resource for future health-economic model simulations, allowing the cost-effectiveness of different management strategies to be evaluated. Such studies may be helpful to achieve a more cost-effective use of the resources in healthcare and society in general.
Acknowledgements
This study was supported by the fifth framework programme of the European Commission. We would like to thank all Eurodiale coworkers: M. Annersten, R. Bem, A. Boykowskov, H. Brill, S. Bus, A. De Leiva, J. De Neve, S. Di Cario, V. Fejfarova, J. Gaitan, D. Geenen, T. Geens, L. Giurato, B. Hempe, M. Hutten, J. Kersken, F. Palumbo, L. Rizzo, R Roel, D. Simon, M. Slak.