How to use data to support improving diagnosis

Predicted prevalance

Prevalence is a measure of the total number of cases in a population. Understanding the variation in prevalence is particularly useful for sites working on the diagnosis stage of the pathway. In order to understand the likely demand for COPD services in your area, the Eastern Region Public Health Observatory estimates predicted prevalence at both PCT and practice level. Predicted prevalence models use information on local heath need such as age, gender, deprivation and smoking status to predict the level of COPD compared to the national average. The data from the prevalence models is used in the comparisons shown below, however if you require the raw information the models and data can be downloaded from the Erpho website

Reported prevalance

Prevalence data is available from QOF on an individual practice level, but also to download for all practices in the country in the data download section.

However, for ease of use, NHS Comparators can provide charts by PCT and Practice, showing the difference in reported prevalence, so each PCT or Practice can be compared to others in the region, or the national average. An example of this data is below:

A graph to show recorded prevalence. The national average prevalence is 1.54% in this example (using 2008/09 data), and all PCTs within this SHA are showing that they have a prevalence below the national average. There is a wide range of difference between the PCTs in this SHA.

NHS Comparators can also provide the same information on a map. This map colours geographical areas depending on their relative level of prevalence. These maps can also be produced at a practice level.

Example of NHS Comparators mapping functionality - Variation in COPD prevalence 2008/09 for London PCTs:

Comparing expected and reported prevalance

Comparison of reported prevalence to predicted prevalence may be helpful in identifying the undiagnosed population. The chart below shows the difference between reported and predicted COPD prevalence across England for 2008/09:

NHS Comparators provides the same information at Practice level, and the ratio between predicted and observed prevalence may be a useful indicator:

Example of the ratio between predicted prevalence and QOF reported prevalence for an example PCT, data from NHS Comparators.