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Using the Functional Comorbidity Index with administrative workers' compensation data: Utility, validity, and
Jeanne M Sears1,2,3, Sean D Rundell1,4,5, Deborah Fulton-Kehoe2
1Department of Health Systems and Population Health, University of Washington, Seattle, Washington, USA.
The Functional Comorbidity Index (FCI) derived from workers' compensation (WC) data shows low sensitivity for identifying chronic conditions and predicting work outcomes. Cross-state use of WC-based FCI may introduce confounding, necessitating caution and state-specific validation.
Area of Science:
- Occupational Health
- Health Services Research
- Biostatistics
Background:
- Chronic health conditions significantly affect worker outcomes but are difficult to quantify using administrative workers' compensation (WC) data.
- The Functional Comorbidity Index (FCI) is established for predicting functional outcomes in community settings but requires validation within WC populations.
- Assessing a WC-derived FCI for identifying chronic conditions and predicting work-related outcomes is crucial for improving worker health management.
Purpose of the Study:
- To validate a workers' compensation (WC)-based Functional Comorbidity Index (FCI) for identifying chronic conditions in injured workers.
- To evaluate the predictive validity of the WC-based FCI for key work-related outcomes.
- To assess the utility of the WC-based FCI for controlling confounding in multi-state studies.
Main Methods:
- Linked administrative WC data with prospective survey data from injured workers in Ohio and Washington.
- Collected survey data at 6 weeks and 6 months post-injury, using survey-derived FCI as the reference standard.
- Assessed predictive validity and confounding control using 6-month work-related outcomes.
Main Results:
- The WC-based FCI demonstrated high specificity but low sensitivity for identifying chronic conditions, with weak associations with work outcomes.
- Survey-based FCI indicated higher comorbidity in Ohio (mean=1.38) vs. Washington (mean=1.14); WC-based FCI showed the reverse (Ohio mean=0.10 vs. Washington mean=0.33).
- Substituting WC-based FCI in multi-state models shifted state effect estimates away from null (8.95% change), unlike survey-based FCI (<1% change).
Conclusions:
- The WC-based FCI may identify specific worker subsets with chronic conditions but is less effective for estimating overall prevalence.
- Cross-state application of the WC-based FCI can introduce significant confounding, potentially distorting study findings.
- Recommend state-specific validation using reliable reference standards before employing WC-based FCI in multi-state research.
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