SHM Converge Scientific Abstract ePoster Gallery-Deconstructing Carlos: Understanding Drivers of Case-Mix Index-Adjusted Resource Length of Stay (Carlos) Variation in Hospital Medicine Through a Disease-Specific Lens

Deconstructing Carlos: Understanding Drivers of Case-Mix Index-Adjusted Resource Length of Stay (Carlos) Variation in Hospital Medicine Through a Disease-Specific Lens

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This study examined how hidden patient-population substructure affects CARLOS (CMI-adjusted resource length of stay) in Hospital Medicine. CARLOS is intended to measure financial output per inpatient bed day, but the authors argue that standard quality-improvement approaches can miss major drivers of variation because they assume a uniform inpatient population.<br /><br />Using all HM discharges from 7/1/24 to 4/1/25, the team identified “mega-outliers” (MOs) defined as CARLOS ≥25 (about 5 SD above the mean). Only 0.6% of admissions (32 patients) met MO criteria, yet they accounted for 3.9% of total inpatient bed days. This means targeting these 32 patients could have a larger theoretical impact on CARLOS than changing 2,486 routine encounters.<br /><br />The study also showed that Diagnosis Related Groups (DRGs) strongly influence expected CARLOS because the DRG determines the CMI, and Medicare GMLOS varies by DRG. Comparing DRGs using a single CARLOS benchmark can therefore lead to misleading conclusions. Seasonal shifts and year-to-year changes in DRG mix and demographics also alter CARLOS, making some variation outside individual providers’ control.<br /><br />A disposition/CMI subgroup analysis found that low-CMI patients with non-home discharge represented 8.9% of HM discharges, had CARLOS 147% above the mean, and created the highest proportional burden to HM. The authors conclude that “below the surface” population effects have outsized influence on CARLOS and should be accounted for in performance measurement and improvement efforts.

Asset Subtitle

Jacob Franco

Meta Tag

Author List Allison L. Schwall, Jacob Franco, Kelly E. Cunningham, Russell Ledford

Category Innovations

Concept CARLOS

Concept Case Mix Index

Concept Length of Stay

Concept Diagnosis-Related Group

Concept Financial Output

Distinguished Non-Finalist

Presenter Organization Vanderbilt University Medical Center

Presenting Author Jacob Franco

Track Transitions of Care

Keywords

CARLOS

Hospital Medicine

patient substructure

mega-outliers

CMI-adjusted resource length of stay

Diagnosis Related Groups

DRG mix

inpatient bed days

non-home discharge

performance measurement

CARLOS

Case Mix Index

Length of Stay

Diagnosis-Related Group

Financial Output