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Inter-provider comparison of patient-reported outcomes: developing an adjustment to account for differences in patient case mix

Research output: Contribution to journalArticle

David Nuttall, David Parkin, Nancy Devlin

Original languageEnglish
Pages (from-to)41-54
Number of pages14
JournalHealth Economics
Issue number1
Publication statusPublished - Jan 2015

King's Authors


This paper describes the development of a methodology for the case-mix adjustment of patient-reported outcome measures (PROMs) data permitting the comparison of outcomes between providers on a like-for-like basis. Statistical models that take account of provider-specific effects form the basis of the proposed case-mix adjustment methodology. Indirect standardisation provides a transparent means of case mix adjusting the PROMs data, which are updated on a monthly basis. Recently published PROMs data for patients undergoing unilateral knee replacement are used to estimate empirical models and to demonstrate the application of the proposed case-mix adjustment methodology in practice. The results are illustrative and are used to highlight a number of theoretical and empirical issues that warrant further exploration. For example, because of differences between PROMs instruments, case-mix adjustment methodologies may require instrument-specific approaches. A number of key assumptions are made in estimating the empirical models, which could be open to challenge. The covariates of post-operative health status could be expanded, and alternative econometric methods could be employed.

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