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Sample size determination for EQ-5D-5L value set studies

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Abstract

Purpose

The EuroQol 5-Dimension (EQ-5D) is a widely used health status instrument for cost-utility analysis of healthcare interventions. Recently, its 5-Level version (EQ-5D-5L) and a protocol for conducting valuation of its health states were developed. We propose four approaches for estimating the sample size for EQ-5D-5L valuation according to the standardized procedures of the protocol.

Methods

The first approach is for estimating mean health state utility values with a desired precision level using a regression model. The second approach, empirical in nature, determines a sample size based on mean absolute error in predicting health state values using a large-scale reference study. The last two approaches are for assessing the significance of regression coefficients of health state descriptors and to estimate the regression coefficients with a desired precision for predicting health state utility values.

Results

Using data from a Singaporean study, we estimated parameters that are useful for sample size determination, including the design effect. Each of the approaches was illustrated with examples and pragmatic recommendations were provided.

Conclusions

Capitalizing on the EQ-5D-5L valuation protocol, we proposed four sample size estimation approaches which can help to decide an appropriate sample size for a value set study.

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Acknowledgements

We thank Juan Manuel Ramos Goñi (Senior Scientist, The EuroQol Office) and Lu Qingshu (Senior Biostatistician, Singapore Clinical Research Institute) for helpful comments on the earlier versions of this article. The authors appreciate the support of Duke-NUS/SingHealth Academic Research Institute and the medical editing assistance of Serene Ong (Medical writer, Duke-NUS Medical School).

Funding

Financial support for this study was provided entirely by a Health Services Research Competitive Research Grant (HSRG/0038/2013) from the National Medical Research Council, Singapore. The last author (YBC) was supported by the National Research Foundation, Singapore, under its Clinician Scientist Award (NMRC/CSA/0039/2012) administered by the Singapore Ministry of Health’s National Medical Research Council. The funding agreement ensured the authors’ independence in designing the study, interpreting the data, writing, and publishing the report.

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Authors and Affiliations

  1. Department of Biostatistics, Singapore Clinical Research Institute, #02-01, Nanos, 31 Biopolis Way, Singapore, Singapore

    Mihir Gandhi

  2. Centre for Quantitative Medicine, Duke-NUS Medical School Level 6, Academia, 20 College Road, Singapore, Singapore

    Mihir Gandhi, Ying Xu & Yin Bun Cheung

  3. Tampere Center for Child Health Research, University of Tampere and Tampere University Hospital, Arvo Building, Lääkärinkatu 1, Tampere, Finland

    Mihir Gandhi & Yin Bun Cheung

  4. Saw Swee Hock School of Public Health, National University of Singapore, Tahir Foundation Building (MD1), 12 Science Drive 2, Singapore, Singapore

    Nan Luo

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  1. Mihir Gandhi
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Correspondence to Mihir Gandhi.

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The authors declare that they have no conflict of interest.

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Informed consent was obtained from all individual participants included in the study.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.

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Gandhi, M., Xu, Y., Luo, N. et al. Sample size determination for EQ-5D-5L value set studies. Qual Life Res 26, 3365–3376 (2017). https://doi.org/10.1007/s11136-017-1685-3

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