Length of stay and therapeutic intervention allow estimation of in-hospital resource use independent of site and inflation

OBJECTIVES: To develop and evaluate a model to estimate inpatient resource utilization for seriously ill patients using periodic medical record abstraction and hospital length of stay. DESIGN: A prospective cohort study of prognoses and preferences and outcomes of seriously ill hospitalized adults. The predictive model was based on the Therapeutic Intervention Scoring System (TISS), length of stay (LOS), and hospital site, and was developed on Phase I data and validated on Phase II data. SETTING: Five teaching hospitals in the United States PARTICIPANTS: The derivation sample included 4301 patients enrolled in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment (SUPPORT). The validation sample included 4804 patients. MEASUREMENTS: Hospital charges were correlated with the product of hospital length of stay and average score from the TISS. Model fit assessment used R-2 for total hospital charges. RESULTS: The correlation between hospital charges and the final model, after adjusting for site differences, was 0.86. The correlation was similar when validating the model in an independent data set. CONCLUSIONS: We present a method to estimate hospital resource utilization that is independent of site and inflation and can estimate actual costs in multiyear, multisite research endeavors.