Should a standard be defined for the Positive Predictive Value (PPV) of recall in the UK NHS Breast Screening Programme?

Abstract

The UK NHSBSP defines standards for both cancer detection rate and recall rate for assessment but has not explicitly set a defined standard for positive predictive value (PPV) of recall. However, as PPV is defined as the percentage of women who are recalled and have a final diagnosis of cancer, a standard for PPV is an implicit consequence of the standards for cancer detection rate and recall rate. The standards are defined in terms of a lower level of acceptability known as the 'minimum standard' and a higher level of acceptability referred to as the 'target'. The target can be shown to be a PPV of more than 5.1% for prevalent screens and more than 8.4% for incident screens. This paper will explore the role of PPV as a performance measure and show how making moderate increases in PPV for programmes with the lowest PPVs could lead to major improvements in the overall efficiency of the programme.