Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark rate for new referrals into a cardiac rehabilitation service are based on the following sources of information:

• ‘Hospital episode statistics' and general practice data to establish the proportion of the population discharged alive per year following an acute admission for a myocardial infarction (MI) or heart failure; and after admission for revascularisation, heart transplant or implantable cardiac defibrillators (ICD); and the proportion of the population identified in the community with angina per year
• published research on cardiac rehabilitation
• expert clinical opinion of the topic-specific advisory group, based on experience in clinical practice and literature review.

Hospital episode statistics data and general practice 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.

The analysis of the data from HES suggests that in 2006/07 0.12%, or 120 per 100,000 population, were discharged alive following an acute admission for an MI and could therefore be given advice about and offered a cardiac rehabilitation programme with an exercise component.

HES analysis in 2006/07 for other patient groups that may be suitable for referral for cardiac rehabilitation following admission to hospital suggests that:

• 0.02%, or 20 per 100,000 population, were discharged alive following percutaneous coronary intervention (PCI)
• 0.04%, or 40 per 100,000 population, were discharged following a coronary artery bypass graft (CABG)
• 0.004%, or 4 per 100,000 population, were discharged following implant of a cardiac defibrillator (ICD)
• 0.07%, or 70 per 100,000 population, were discharged alive following an acute admission for heart failure.

People who had multiple admissions in the year, and people who had more than one of the procedures and/or diagnoses were counted just once.

Other groups that may benefit from cardiac rehabilitation include people who have received heart transplants. The rate of heart transplants in the population per year is small, around 3.3 per million.

People with stable angina may also be suitable for cardiac rehabilitation. On the basis of data from IMS disease analyzer, a database that holds data on a sample of GP practice databases, the annual incidence of diagnosed angina - that is, the average detection rate of new cases - is 0.05% per year. This is likely to be an underestimate of the need among this group, as many people with diagnosed angina will have not been offered cardiac rehabilitation.

Published research

The NICE clinical guideline CG48 on MI: secondary prevention states that all patients after an MI (regardless of their age) should be given advice about and offered a cardiac rehabilitation programme with an exercise component.

Poor referral, take-up and attendance have been identified as problems facing cardiac rehabilitation services in the UK^[1],^[2]. There are several reasons for the lower than expected levels of participation. These include a lack of engagement (people not invited to attend cardiac rehabilitation), low levels of referral, scarcity of service provision, and poor take-up due to practical reasons (for example, location and time of the session).

A 2004 health technology assessment ‘Provision, uptake and cost of cardiac rehabilitation programmes: improving services to under-represented groups' suggested that take-up of cardiac rehabilitation could be improved by addressing the barriers to take-up (see Specifying a cardiac rehabilitation service).

It is assumed that optimal service design would lead to an increase in take-up and attendance in cardiac rehabilitation, and that those services with current high levels of take-up and attendance may be operating closer to optimal service design.

Currently around 55% of people who are invited or referred to cardiac rehabilitation attend; however, estimates vary between 35% and 80% across services. Therefore the optimal take-up of cardiac rehabilitation could be around 80% or more.

Expert clinical opinion

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

• on average, around 80-90% of people post MI should be suitable for referral to a cardiac rehabilitation service, of which around 80% could optimally take up the offer, providing that current barriers are addressed
• the majority of people post revascularisation (CABG and PCI) and ICD implant would be suitable for referral for cardiac rehabilitation, and the take-up of those referred would be around 85%
• on average, around 70-80% of people with heart failure would be suitable for cardiac rehabilitation, and the take-up of those referred would be around 60-80%
• the numbers of people presented within the commissioning and benchmarking tool and used to estimate the population benchmark may be an underestimate of the need, because some people may require more than one course of cardiac rehabilitation in the year.

The estimates on the take-up and referral of cardiac rehabilitation provided by the topic-specific advisory group are based on best practice and are the proportions that could be achieved given optimal service design.

Conclusions

Based on the epidemiological data and other information outlined above, it is concluded that 0.20% of the population would be suitable for referral to a cardiac rehabilitation service. This is based on the following assumptions (see also table 1):

• the percentages of the population discharged alive for the indicated conditions or following a revascularisation procedure or ICD implant
• the mid-points of the ranges for suitability for cardiac referral and expected optimal take-up of services under ideal circumstances suggested by the topic-specific advisory group
• the suitability for cardiac rehabilitation among people discharged alive after an MI, revascularisation, heart failure, angina and ICD implantation based on the mid-points suggested by the topic-specific advisory group
• the diagnosed incidence of angina in the population of around 0.05% per year.

Table 1 Assumptions used in the population benchmark for cardiac rehabilitation based on 2006/7 hospital activity data and expert clinical opinion

Diagnosis/procedure	Percentage of population discharged alive in 2006/07	Percentage of discharged population suitable for cardiac rehabilitation referral	Percentage (optimal) of population suitable for referral who take up cardiac rehabilitation	Combination of referral and optimal take-up (percent) - that is, attendance	Percentage (optimal) of discharged population who take up cardiac rehabilitation based on 2006/7 data
Myocardial infarction	0.12	85	80	68	0.082
Percutaneous coronary intervention	0.02	100	85	85	0.017
Coronary artery bypass graft	0.04	100	85	85	0.034
Heart failure	0.07	75	70	53	0.037
Implant of a cardiac defibrillator	0.004	100	85	85	0.0034

Therefore the population benchmark for a cardiac rehabilitation service is estimated to be 0.20%.

Use the cardiac rehabilitation 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. Bethell H, Evans J, Malone S et al. (2005) Problems of cardiac rehabilitation coordinators in the UK: are perceptions justified by facts? British Journal of Cardiology 12: 372­-8.

2. Beswick AD, Rees K, Griebsch I et al. (2004) Provision, uptake and cost of cardiac rehabilitation programmes: improving services to under-represented groups. Health Technology Assessment 8: 1-166.