Initial presentation of older injured patients to high-volume hospitals is not associated with lower 30-day mortality in Medicare data*

Abstract

To evaluate whether survival of older patients with severe injuries is positively associated with initial presentation to high-volume trauma hospitals. Historical cohort study. We analyzed Medicare fee-for-service records. Cases were classified by maximum Abbreviated Injury Score (AISmax); those with isolated hip fractures or AISmax <3 were excluded. The initial hospital (emergency department or inpatient) for each case was classified by its number of included inpatient cases. Patients aged >or=65 with principal injury diagnoses (ICD-9 800-959, excluding 905, 930-939, 958) admitted to hospitals or who died in emergency departments during 1999. None. Thirty-day mortality was determined using Medicare denominator data and modeled as a function of hospital volume, AISmax, age, gender, and comorbidity. We found that 95,867 patients (74,894 AISmax = 3; 17,932 AISmax = 4; 3,041 AISmax = 5) were managed in 4,391 hospitals. More than 90% of the interhospital transfers were from emergency departments, mostly from low-volume to high-volume hospitals, and were more frequent with greater severity. Regression models showed no difference in 30-day survival between patients taken first to low-volume hospitals (and possibly transferred) vs. patients taken directly to high-volume hospitals. Prior studies showing a positive or negative effect of hospital volume on survival of older patients could be replicated but their findings could not be generalized. Existing systems of trauma care result in similar survival for older patients with serious injuries seen first at low-volume or high-volume hospitals.