Report on using the GPPS to assess trends in EQ-5D scores for people with long-term conditions

Background: Estimating the extent to which NHS services are contributing to improving the health-related quality of life (HRQoL) of people with long-term conditions is an important (if challenging) objective. Its importance is reflected in domain 2 of the NHS Outcomes Framework. Understanding whether this goal is being achieved requires methods which help the interpretation of the role of services on observed trends in HRQoL. Controlling for the influence of external factors, such as the severity of the underlying condition – or ‘need’ – on quality of life, is particularly crucial because NHS and care activity levels increase with need-related factors (NRFs), but otherwise NRFs are strongly associated with worse HRQoL. Failing to control for NRFs makes it therefore very difficult to interpret observed changes in quality of life, and in particular to appraise the role that NHS and care services might play in improving the well-being of people with long-term conditions. This report aims to develop a methodology which is easy to implement and which standardises for changes in NRFs when investigating changes through time in the HRQoL of people with long-term conditions.