We identified six distinct groups of pathways, which represented typical care pathways at different stages of the development of foot complications into more severe conditions such as ulcers that could ultimately lead to amputation [1, 23]. We also separately examined the group of patients who had died during the two-year follow-up. Each of the group of pathways mainly comprised care episodes under a single diagnostic category, with the Deceased group as an exception. This reflects the fact that the treatment of foot complications is managed by multiple specialties, each of them responsible for a certain aspect of care or a specific complication . Within the four largest groups (Infection, low frequency Dermal, Orthopedic and Neuropathy), the majority of the complications could be treated at a single treatment episode, after which only a minority of patients required further treatment. In the Deceased group, notably higher level of heterogeneity was observed in the types of care episodes. Nonetheless, dermal care episodes were most prevalent which is consistent with the observation that the risk of mortality within five years increases substantially after initial ulceration .
Low and high frequency Dermal groups comprised purely dermal care episodes. These groups represented typical treatment pathways for active ulcers with different levels of need, i.e. high frequency Dermal comprising more severe cases with a need for continuous care. The three other groups (Infection, Orthopedic and Neuropathy) represented care pathways for infections, conditions requiring orthopedic care and neuropathy, which is a major precursor to foot ulcers .
Old age and longer duration of diabetes have been associated with elevated risk of foot complications . Our study population had an average age of 66 years and had lived with diabetes for over a decade before the start of their initial care pathway. Overall, the proportions of men and women were approximately equal, however, the sex distributions between groups of pathways differed to some extent. The share of men was higher in the Neuropathy and high frequency Dermal groups which is in line with the observed role of male sex as a risk factor . In addition, other risk factors were more prevalent in the high frequency Dermal group than the other groups: the patients were older and had a longer duration of diabetes, as well as higher prevalence of comorbid late-stage complications.
The total costs of the studied pathways were approximately EUR 70 million (USD 84 million). Assuming an equal number of pathways per year, this represents an annual cost of EUR 13 million (USD 16 million), which constitutes approximately 1.6% of diabetes-related healthcare costs in Finland (estimates from 2011) . In the UK, the costs of health care for ulceration and amputation were estimated to be around 0.8–0.9% of total NHS budget of which 60% occurred in care episodes in community, outpatient and primary settings . We arrived at a notably lower estimate for the share of total healthcare budget (0.06%), and slightly lower estimate (40%) for the share of primary and outpatient care. However, the estimates are not easily comparable to estimates of annual total costs in the existing literature, due to differences in study design and cost items included.
We observed that the total costs of low and high frequency Dermal groups totaled up to one-third of the total costs for the study population. This differs markedly from the estimate of NHS’s, which states that 90% of foot complication costs were attributable to ulceration . The annual costs of high frequency Dermal group (EUR 5 958) were over eight-fold compared to the overall mean costs and very close to the reported annual cost of ulcer treatment in the UK in 2010–2011 (EUR 5 104) .
Even though most of the conditions in the Infection, Orthopedic and Neuropathy groups could be managed with a single treatment episode, their total costs comprised a substantial proportion (40%) of all costs. As treatment options for neuropathy are mainly limited to medication aimed at symptomatic relief  and neuropathy suffers from underdiagnosis the total costs remained moderate compared to other groups. The Deceased group had higher total costs compared to other groups of pathways, mainly resulting from large volume of specialized inpatient care. This is not surprising, since healthcare costs have been shown to increase notably in close proximity to death .
Costs were to a large extent care-specific: the differences between groups of pathways mainly remained after adjusting for the background variables. The diminished difference between the Neuropathy and Infection groups could be explained by differing patient characteristics: a patient in the Neuropathy group was more likely male and more probably suffered from late-stage complications which both associate with higher costs. Despite differences in the clinical presentation of type 1 and type 2 diabetes , we did not observe association between diabetes type and the mean costs. This could reflect the fact that care guidelines do not specify care according to diabetes type .
The variability in the number of care episodes and pathway-specific costs is most probably attributable to two main factors: the diversity in the individual need for care and regional differences in the resource availability and organization of care. Multimorbidity is typical for people with diabetic foot, also affecting treatment practice . Accounting for multimorbidity requires tailoring of services to meet the individual needs of patients, possibly increasing the number of care episodes as well as the costs of each care episode . As regular surveys among Finnish diabetes professionals have pointed out, some areas are unable to reach the standards set in the national current care guidelines [12, 29]. However, specific regional estimates are not available.
We limited our perspective to health care and only included the costs of diabetes foot complications. However, individuals and households living with diabetes may also encounter substantial non-healthcare costs, for example, through lost working ability and social care. This generates an additional economic burden on society through lost productivity and subsequent social security costs. A recent study in Finland associated diabetes foot complications with increased risk of early exit from the workforce and productivity loss .
Based on reliable and extensive register-based data, we characterized the typical care pathways of patients with diabetic foot using an analysis method that grouped similar care pathways. While we believe that this method is a powerful tool for extracting information from extensive data, it requires subjective decisions regarding its parameters (e.g. time origin and unit, definition of states, measures of similarity). We conducted several alternative analyses with different choices and the results were not particularly sensitive to the chosen parameter values. We aimed at providing an overall picture of the typical care pathways for foot complications and therefore defined the states in our analysis to represent groups of complication diagnoses and excluded examination of procedures. In a study design with focus on a particular endpoint (such as amputation), a more detailed approach would be justified.
Presently, many health care systems throughout the world face the challenge of an aging population and an increasing diabetes prevalence. This places considerable stress on the individual well-being and sustainability of healthcare systems. Finland is not immune to these challenges: the proportion of people aged 65 or over is predicted to increase from 20% to nearly 30% in the next 30 years and the healthcare costs of diabetes are expected to follow a similar trend . The resources available for foot complication treatment are likely to remain scarce in the near future. Thus, better prevention and timely diagnosis to prevent the development of diabetic foot can only be achieved using cost-effective technologies and the more efficient organization of care. Ensuring adequate secondary prevention services and enhancing the patient-centered collaborative care of diabetes should be given a high priority. In the near future, a national register of diabetes care will be launched in Finland . This will enable better monitoring of the quality, effectiveness and costs of diabetes care on a national level.
The main strength of our study is that the analyses are based on population-wide individual-level data. This enables the reliable estimation of service use and costs for people with diabetes foot complications. However, the majority of diagnosing in primary outpatient care is conducted using International Classification of Primary Care 2 (ICPC-2) codes . Due to the inaccuracy of the codes, we could not identify all primary outpatient care episodes related to foot complications. This could result in the underestimation of primary care episodes in the pathways, e.g., the treatment for active ulcers is typically provided by public health nurses after an initial visit to a primary care or specialized care unit and is provided at a patient’s residence, sometimes even on a daily basis. Since these visits are registered as primary care visits using ICPC-2 coding, it is possible that some of the care episodes were excluded from the pathways. We believe this limitation has the largest effect on the pathways of the groups with a high frequency of dermal care episodes.
Information about certain relevant costs such as outpatient medication and diabetic footwear was not included in the data. Thus, our estimates are conservative, which could explain the rather large deviance from the ADA’s and NHS’s estimates of diabetic foot care costs. In Finland, the costs of outpatient medication is shared by the patient and national health insurance and therefore the healthcare system does not directly bear these costs. However, diabetic footwear is provided for patients by the health services and the costs can constitute a notable proportion of the pathway’s overall costs in the shorter pathways.
The reasons underlying the heterogeneity of pathways requires further research. Treatments recommended in the national guidelines are also considered from the perspective of their cost-effectiveness with the aim of improving the provision of health care. Thus, it would be useful to investigate how the national guidelines related to diabetic foot are followed among different specialties and regions and which factors complicate the provision of adequate care. The mapping of regional care practices for diabetes foot complications, together with assessments of their effectiveness, would help identify the best management strategies and enable the co-creation of more effective diabetic foot care.