Mapping utilities from cancer-specific health-related quality of life instruments: a review of the literature

Abstract

Cancer-specific health-related quality of life instruments are often used to evaluate the patients’ quality of life in clinical trials. However, these instruments cannot be used in economic evaluation to guide resource allocation decisions. Mapping is an approach that enables utilities to be predicted for use in cost-utility analysis. The purpose of this study was to review the literature on the mapping methods used to determine utilities from two cancer-specific instruments. Thirteen studies were identified and a total of 53 models were reported. Most of the studies employed an ordinary least squares method and did not conduct an out-of-sample validation. There is a need for more rigorous and robust mapping studies to be conducted to ensure appropriate funding recommendations are being made.

Keywords::

• cancer-specific instruments
• cross-walking
• mapping
• review
• utilities

Acknowledgements

The authors would like to thank B Morrison for conducting the literature searches and R Pataky for reading an earlier version of this manuscript.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire and the Functional Assessment of Cancer Therapy – General are cancer-specific health-related quality of life instruments used to evaluate patients’ quality of life.

• • Responses on cancer-specific health-related quality of life instruments cannot be used in used in a general health policy model to compare the efficiency of different programs or treatments.

• • Mapping is an approach that enables utility values to be predicted for economic evaluation when no preference-based information has been elicited by generating a statistical relationship between cancer-specific and preference-based instruments.

• • There are number of mapping studies that have been conducted in cancer; this raises the question regarding the quality of the mapping techniques being utilized.

• • The majority of the studies identified in this review used an additive model with ordinary least squared regression to determine the mapping algorithms.

• • The reliability of mapping results depend on the distribution of the scores and whether appropriate statistical modeling is adopted.

• • Most of the studies validated their mapping functions; however, only two used an out-of-sample approach. Mapping studies in the future needs to include an external validation.

• • While responses on generic preference-based instruments are preferred within an economic evaluation framework, mapping is a second best approach.

Notes

Data taken from [18].