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Abstract

Introduction: Patient characteristics are an important contributor to intensive care unit (ICU) cost. Few studies, however, have focused on the influence of patient factors on cost. Hypothesis: After adjusting for ICU length of stay (LOS) and specific hospital, patient characteristics such as severity of illness, age, and diagnosis will be major contributors to overall ICU cost. Methods: Retrospectively, ICU cost data were obtained for all admissions to 13 ICUs at four U.S. hospitals during 2006 - 2010. Cost data for each admission were matched with that patient’s respective clinical and demographic data in the APACHE® database. We excluded readmissions, lengths of stay (LOS) < 1 day, and CABG patients. ICU cost was adjusted for the annual in-patient inflation rate through information provided by the Bureau of Labor Statistics, and the natural log of inflation-adjusted cost was calculated. We then developed a multivariable linear model to determine the largest contributors to variation in costs across patients. Predictor variables included ICU LOS, each hospital (n=4) as a fixed effect, the acute physiology score component of the APACHE III score, diagnosis (n=57), day 1 mechanical ventilation (MV), other day 1 life supporting therapy, patient location as well as length of stay before ICU admission, age, gender,? 1 APACHE chronic health item, and mortality before unit discharge. Results: Among 15,002 admissions meeting inclusion criteria, 12,554 (84%) had financial data that could be matched with their respective APACHE data. The mean cost of an ICU stay was $19,272 (median = $9,476, IQR = $4,812 - $20,075). There was substantial variation in costs among hospitals. After adjusting for ICU LOS and specific hospital, the following variables contributed the most to variation in costs (in descending order): day 1 MV, acute physiology score, day 1 life support other than/in addition to MV, and length of hospital stay before ICU admission. All were significant at p <.001. Conclusions: Life supporting therapy and physiologic derangement greatly impact total ICU cost. Benchmarks based on age and diagnosis may prove insufficient for comparing ICU costs.