Case-mix methodology for the NHS outcomes framework GP Patient Survey Questionnaire Data

The objective of the research described in the current report was to explore alternative methodologies which could be used to determine whether the health status of people living with long- term conditions in England is changing over time, all other factors being equal. Data from the Health Survey for England (HSE) were used in the analyses and EQ-5D was used to represent health related quality of life (HRQoL). The proposed case mix ratio approach which utilised ordinary least square regressions (with the EQ-5D preference - based score as the dependent variable) was replicated and alternatives using logistic regressions and two part models (both using the responses to the EQ-5D health dimensions as the dependent variables) were explored. An alternative method using the HSE year as a performance indicator (PI) was explored and results presented for the four most prevalent health conditions. Results were compared in terms of errors in predicted scores and the ability to capture changes in the distributions of the preference-based scores. Both expected and simulated values were compared.