Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark rate for new referrals into a heart failure service of 0.5%, or 500 per 100,000 population, aged 45 years or older are based on the following sources of information:

• epidemiological data on the prevalence/incidence of heart failure
• ‘Hospital episode statistics' data to establish the rate of emergency admissions for heart failure
• current practice on detection rates of heart failure
• published research on heart failure
• expert clinical opinion of the topic-specific advisory group, based on experience in clinical practice and literature review.

Epidemiological data

In 2007, the Healthcare Commission's service review ‘Pushing the boundaries: improving services for people with heart failure' suggested that the prevalence of confirmed heart failure in the population aged 45 years or older is 1.81%, with large variation across the country.

It also suggested that the expected prevalence of heart failure is around 2.30% of the population aged 45 years or older and that some people may not be getting access to appropriate diagnostic tests and subsequent treatment.

Figure 1 illustrates the percentage of the population aged 45 years or older with a confirmed diagnosis of heart failure or LVSD compared with the estimated population prevalence of heart failure or LVSD.

Activity data - ‘Hospital episode statistics' data

The ‘Hospital episode statistics' (HES) database contains details of all admissions to NHS hospitals in England. It includes private patients treated in NHS hospitals, patients who were resident outside England and care delivered by treatment centres (including those in the independent sector) funded by the NHS.

Analysis of 2006/07 HES data suggests that the mean directly standardised rate of emergency admission into secondary care for heart failure was around 110 per 100,000 population, with wide variation across the country (see figure 2).

All people discharged from hospital with a diagnosis of heart failure may require support from heart failure services as described in NICE clinical guideline CG5 on chronic heart failure. However, currently only around one quarter of people discharged alive following an admission for heart failure are referred to a heart failure service^[1].

It has been estimated that the effective management of heart failure after an acute admission can reduce re-admission into secondary care by 30-50% in the short and medium term^[2].

Current practice

Analysis of data extracted from IMS Disease Analyser, a database that holds data from a sample of GP practice systems, indicates that the annual incidence of diagnosed heart failure (that is, the average detection rate of new cases in a year) is around 0.07% of the population or 0.16% of those aged 45 years or older.

Heart failure is known to be under-diagnosed in primary care. The Healthcare Commission's heart failure benchmarking toolkit provides information by primary care trust on the prevalence of confirmed heart failure against the expected prevalence of heart failure in the population. This toolkit may be used to assess levels of unmet need in the population and possible misdiagnoses of heart failure.

Published research

Not all people with suspected heart failure who are referred for specialist assessment are subsequently diagnosed with heart failure. The proportion of people referred who are subsequently diagnosed with heart failure varies between studies and services. The mid point of these estimates suggest that around 40% of patients with suspected heart failure have the diagnosis confirmed^[3],^[4],^[5],^[6].

Expert clinical opinion

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

• It may be possible to increase the detection and diagnosis rates of people with heart failure by raising awareness among clinicians of the public health importance of heart failure, and by improving referral pathways, access to diagnostic services and access to coordinated care.
• Commissioners should examine local prevalence rates against expected rates to determine potential levels of unmet need in their populations and possible levels of misdiagnoses.
• Commissioners may find it helpful to examine their local emergency admissions rates for heart failure link to ‘The commissioning tool' and other data such as Quality and Outcomes Framework (QOF) and prescribing data to assess current service provision.
• Examining length of hospital stay may also prove helpful as some people with heart failure may be discharged before being stabilised. The auditing of heart failure services to assess if there is age and gender bias may also prove useful.

Conclusions

Based on the epidemiological data and other information outlined above, it is concluded that the benchmark for new referrals in to a heart failure service is 0.5% of the population aged 45 years or older per year. This is based on the following assumptions:

• The estimated expected prevalence of heart failure in the population aged 45 years or older is around 2.30%. Some of these people will have been diagnosed with heart failure, whereas others will be currently undiagnosed.
• The estimated prevalence of confirmed heart failure in the population aged 45 years or more is around 1.8%.
• An increase of around 30% in the estimated current levels of people aged 45 years and older diagnosed with heart failure would be required to reach the expected prevalence of heart failure in this population.
• The current annual detection rate of new cases (that is, the incidence of diagnosed heart failure) is 0.16% of people aged 45 years or older per year.
• Increasing the current annual detection rate of new cases by around 30% (the difference between current estimated and expected prevalence levels) comes to around 0.21% per year.
• The estimates from published research suggests that around 40% of people aged 45 years or older with suspected heart failure referred for specialist assessment have the diagnosis of heart failure confirmed.
• Increasing the estimate of new referrals (0.21%) to take into account the estimated 60% of people who are referred but not subsequently diagnosed with heart failure results in a benchmark of 0.53%.

Therefore the population benchmark for new referrals into a heart failure service is estimated to be 0.5% of the population aged 45 years or older per year, of which around 40% (around 0.2%) are likely to have the diagnosis of heart failure confirmed.

Use the heart failure 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.

References

1. Healthcare Commission (2007) Pushing the boundaries: improving services for people with heart failure. London: Commission for Healthcare Audit and Inspection.

2. Stewart S, Horowitz JD (2003) Specialist nurse management programmes: Economic benefits in the management of heart failure. Pharmacoeconomics 21: 225-40.

3. Wheeldon NM, MacDonald TM, Flucker CJ, et al. (1993) Echocardiography in chronic heart failure in the community. Quarterly Journal of Medicine 86: 17-23.

4. Clarke K, Gray D, Hampton JR (1994) Evidence of inadequate investigation and treatment of patients with heart failure. British Heart Journal 71: 584-7.

5. Francis CM, Caruana L, Kearney P et al. (1995) Open access echocardiography in management of heart failure in the community. British Medical Journal 310: 634-6.

6. Murphy JJ, Frain JP, Ramesh P et al. (1996) Open-access echocardiography to general practitioners for suspected heart failure. British Journal of General Practice 46: 475-6.