The relationship between hospital per diem billing and DRG reimbursement for urban trauma patients

Abstract

Study objective: To study the relationship between a trauma center per diem charges and medicare DRG reimbursement.

Design: Retrospective comparison of charges ($630/day, $1500/ICU day) and hypothetical DRG reimbursement using medical records ICD-9 N and P codes and version 5.0 of grouper.

Setting: An urban level I trauma center that participates in a trauma system that serves a population of three million people.

Patient population: Trauma patients > or = 16 years old (mean age of 32 years) admitted and discharged between 1/1/88 and 9/30/88. The group was 86% male, 75% black, with a blunt mechanism of injury in 64%. The mean ICU stay was 0.9 days, and the mean total length of stay was 5.0 days.

Results: Total per diem charges were $8,652,159, and DRG reimbursement was $8,636,505, causing a net loss of $15,654, or 0.2% of charges. Mean charges and reimbursement did not differ for the entire group. The mean loss per patient was $8. Mean charges and reimbursement differed in penetrating trauma patients (mean loss = $138), as well as those with different lengths of stay. The correlation between charges and reimbursement was 0.42; for penetrating trauma patients, the correlation was 0.58. (p < .001)

Conclusion: If DRG reimbursement were provided for all admitted trauma patients, the amount would equal per diem rates. Trauma centers with similar patients and lengths of stay can use these per diem rates to estimate DRG reimbursement.