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Refined comorbidity index based on dimensionality of comorbidity for use in studies of health-related quality of life

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Abstract

Purpose

To refine two subscales of the health-related quality of life comorbidity index (HRQoL-CI) into a single index measure.

Methods

The 2010 and 2012 Medical Expenditure Panel Surveys were utilized as development and validation datasets, respectively. The least absolute shrinkage and selection operator was applied to select important comorbidity candidates associated with HRQoL. Exploratory factor analysis and confirmatory factor analysis (CFA) were used to assess dimensionality in comorbidity. Statistical weights were derived based on standardized factor loadings from CFA and regression coefficients from the model predicting HRQoL. Prediction errors and model R2 values were compared between HRQoL-CI and Charlson CI (CCI).

Results

Eighteen comorbid conditions were identified. CFA models indicated that the second-order multidimensional comorbidity structure had a better fit to the data than did the first-order unidimensional structure. The predictive performance of the refined scale under a multidimensional structure utilizing statistical weights outperformed the original scale and CCI in terms of average prediction error and R2 in the prediction models (R2 values from refined scale model are 0.25, 0.30, and 0.28 versus those from CCI of 0.10, 0.09, and 0.06 for general health, SF-6D, and EQ-5D, respectively).

Conclusion

The dimensionality of comorbidity and the weight scheme significantly improved the performance of the refined HRQoL-CI. The refined single HRQoL-CI measure appears to be an appropriate and valid instrument specific for risk adjustment in studies of HRQoL. Future research that validates the refined scales for different cultures, age groups, and healthcare settings is warranted.

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Acknowledgments

We gratefully acknowledge the support from National Cheng Kung University (Tainan, Taiwan) and the University of Michigan (Ann Arbor, Michigan, United States).

Funding

The research was supported by a grant to Huang-tz Ou from the Ministry of Science and Technology, Taiwan (NSC 102-2320-B-006-044-MY2). The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Author information

Authors and Affiliations

  1. Institute of Clinical Pharmacy and Pharmaceutical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan

    Huang-Tz Ou

  2. Department of Rehabilitation Sciences, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong

    Chung-Ying Lin

  3. Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA

    Steven R. Erickson

  4. Department of Public Health Sciences, School of Medicine, University of Virginia, Charlottesville, VA, USA

    Rajesh Balkrishnan

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  1. Huang-Tz Ou
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  2. Chung-Ying Lin
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  4. Rajesh Balkrishnan
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Corresponding author

Correspondence to Huang-Tz Ou.

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Conflict of interest

None of the authors has any conflict of interest to declare.

Ethical approval

This study utilized the Medical Expenditure Panel Survey (MEPS), which is a series of household surveys of U.S. citizens and provides de-identified data for public use. MEPS is available at http://www.meps.ahrq.gov/mepsweb/. Because of de-identified data, informed consent was not possible to obtain from individuals involved in the survey. However, the MEPS data were reported and analyzed anonymously, and permission for the study from the Institutional Review Board of National Cheng Kung University Hospital was obtained before study commencement.

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Ou, HT., Lin, CY., Erickson, S.R. et al. Refined comorbidity index based on dimensionality of comorbidity for use in studies of health-related quality of life. Qual Life Res 25, 2543–2557 (2016). https://doi.org/10.1007/s11136-016-1306-6

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  • DOI: https://doi.org/10.1007/s11136-016-1306-6

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