Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark of the number of people with diagnosed diabetes requiring foot care are based on the following sources of information:

• epidemiological data on the prevalence of diagnosed diabetes within the population, and the prevalence of risk factors for foot ulceration among people with diabetes
• expert clinical opinionof the topic-specific advisory group, based on experience in clinical practice and literature review.

Epidemiological data

The 2010/2011 Quality and Outcomes Framework (QOF) results indicate that 5.5% of the population has diagnosed diabetes. This is likely to be an underestimate of the actual prevalence of diabetes within the population, due to QOF exception reporting, and under-diagnosis[1].

The APHO diabetes model provides estimates of total (diagnosed and undiagnosed) diabetes prevalence for people aged 16 years and older for 2009, 2010, 2015, 2020, 2025 and 2030 and thus allows for planning of future service provision.

The proportion of people with diabetes who are at an elevated (increased or higher) risk of developing foot ulcers may be estimated from the prevalence of diabetic neuropathy and peripheral vascular disease (PVD), both of which are complications of longstanding diabetes.

Published research indicates that 20-40% of people with diabetes are estimated to have neuropathy and around 2-5% are likely to have foot ulcers[2],[3],[4],[5] . Published research also indicates that around 19-29%[6],[7] have PVD. These values depend on how PVD and neuropathy are defined and measured. Research also indicates that there is a considerable overlap in the proportion of people with diabetes who have PVD and those with neuropathy[8], and has been estimated to be around 13%[9].

Based on the midpoints of the estimates on the prevalence of PVD (24%) and neuropathy (30%), and taking into account a 13% overlap, an estimated 41% of people with diabetes are at an elevated risk of foot ulceration. The remaining 59% of people with diabetes will be at low current risk.

Using published research it has not been possible to determine the proportion of people with diabetes at elevated risk who fall into the different risk categories for foot ulceration. See the NICE clinical guideline CG10 on type 2 diabetes: prevention and management of foot problems and the NICE clinical guideline CG15 on type 1 diabetes: diagnosis and management of type 1 diabetes in children, young people and adults.

Expert clinical opinion

The consensus opinion of the topic-specific advisory group was:

• approximately 60% of people with diabetes are likely to be at low risk of foot ulceration, but will require a management plan including foot care education as indicated in the NICE clinical guidelines CG10 on type 2 diabetes - foot care and CG15 on type 1 diabetes
• approximately 40% are likely to be at some degree of elevated risk of foot ulceration of which:25-28% are likely to be at increased risk
  • 10% are likely to be at high risk
  • 2-5% are likely to require emergency foot care.

Conclusions

Based on the epidemiological data and the estimates from the consensus opinion of the topic-specific advisory group above, the population benchmark for a diabetic foot care service is 2.2%.

This is based on the population prevalence of diagnosed diabetes of 5.5%, of which:

• 26.5% of people with diabetes - or 1.46% of the population age 17yrs and older - are likely to be at increased risk of foot ulceration. This is based on the midpoint of the estimate provided by the topic-specific advisory group (25-28%).
• 10% of people with diabetes - or 0.55% of the population age 17yrs and older - are likely to be at high risk of foot ulceration. This is based on the estimate provided by the topic-specific advisory group.
• 3.5% of people with diabetes - or 0.19% of the population age 17yrs and older - are likely to require emergency foot care. This is based on the midpoint of the estimates provided by the topic-specific advisory group (2-5%).

This means that 40% of people with diagnosed diabetes aged 17 or over (5.5% of the population) will require review and treatment at a level and frequency above the standard which is recommended for all people with diagnosed diabetes. This translates into a population benchmark of 2.2%.

However, 60% of people with diabetes aged 17 or over - or 3.3% of the population as a whole - are likely to be at low current risk. Commissioners should consider that these people require an annual review, which should include an examination of their feet to detect risk factors for ulceration.

Use the foot care service commissioning and benchmarking tool to determine the level of service that might be needed locally and to calculate the cost of commissioning the service using the indicative benchmark and/or your own local data.

Commissioners should use their local needs assessment to determine optimum levels for local service provision. Commissioners should note that the benchmark rates do not represent NICE's view of desirable, or maximum or minimum, service levels.

Commissioners should use this benchmark and local data to facilitate local discussion on optimum service levels. There is considerable variation in the number of people with diabetes. This is influenced by the social, economic and demographic profile of the local population, therefore commissioners are encouraged to consider local assumptions.