Risk adjustment for injured patients using administrative data
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Updated: Aug 23, 2026
Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index
Published on: January 8, 2020
David E Clark1, Robert J Winchell
1Department of Surgery, Maine Medical Center, Portland, Maine, USA. clarkd@mmc.org
Background:
Risk adjustment methods are needed for population-based studies of injured patients.
Methods:
Data were obtained from National Hospital Discharge Surveys, 1996 to 2000. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnoses were used to categorize Abbreviated Injury Scale score, Injury Severity Score, ICD-9-CM Injury Severity Score, injury mechanisms, and comorbidities. Regression models for weighted survey data were constructed from combinations of these classifications, plus age and sex, to predict mortality, length of stay (LOS), or discharge to long-term care (LTC).
Results:
Increased Abbreviated Injury Scale score, increased Injury Severity Score, or decreased ICD-9-CM Injury Severity Score were similarly associated with mortality, prolonged LOS, or more frequent LTC, as was increased age. Penetrating or burn mechanisms were associated with mortality and longer LOS; penetrating or vehicle mechanisms were associated with less frequent LTC. Different comorbidities affected LOS and LTC. Men had shorter LOS and less frequent LTC than women.
Conclusion:
Hospital outcomes after injury are predictable from age, sex, and standard diagnosis groupings. Anatomic scales gave similar results when adjusted for other factors.