Assumptions used in estimating a population benchmark

The assumptions used in estimating a population benchmark of 0.23% requiring pulmonary rehabilitation per year are based on two sources of information:

• epidemiological data estimating the prevalence of chronic obstructive pulmonary disease (COPD) by severity
• current practice where there is an established pulmonary rehabilitation service.

Epidemiological data

Epidemiology - or prevalence of symptoms in the population - provides an estimate of the numbers that are likely to meet the referral criteria.

Ideally, to estimate the number of patients eligible for pulmonary rehabilitation, the incidence of cases of COPD each year who are MRC (Medical Research Council) grade 3 or above would be used. This assumes that each eligible patient may require an initial course of pulmonary rehabilitation.

However, in the absence of any reliable national data on the incidence of COPD, we have used Quality and Outcomes Framework (QOF) COPD prevalence as it provides the proportion of people with diagnosed COPD in a population on which an estimate of those who are likely to be MRC grade 3 or above can then be made.

2006/2007 QOF data indicates the national prevalence of diagnosed COPD is 1.4%. However, commissioners should be aware that COPD is known to be under diagnosed in the population.

In the absence of appropriate published data on COPD by severity in a general population, clinical opinion suggests that the proportion of people with diagnosed COPD at MRC grade 3 or above is approximately 25%.

It is considered that prevalence is appropriate to use when commissioning a new service as there will be a number of people with COPD who are eligible for, but have not previously received, pulmonary rehabilitation. A local strategy will need to be developed to manage the number of eligible patients who may benefit through the service.

Where services are already established, local incidence and referral rates would be more appropriate on which to base commissioning intentions.

Current practice

Clinical experience of existing pulmonary rehabilitation services suggest that the uptake rate in the population eligible for pulmonary rehabilitation is approximately 67%.

This means that you may need to consider commissioning services for 0.23% of the general population (230 per 100,000). This is based on:

• 1.4% prevalence of diagnosed COPD, of which
• 25% are eligible for pulmonary rehabilitation, of which
• there is an uptake of 67%.

Conclusions

From the information above, we can conclude that:

• the proportion of the population eligible for pulmonary rehabilitation based on population prevalence and COPD MRC grade 3 or above is 0.35%
• the rate based on experience from current practice where pulmonary rehabilitation schemes are operating is 0.23%.

As the information from schemes already operating is likely to be more valid, a benchmarking estimate of 0.23% has been selected.

Use the pulmonary 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.