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

Objective: To evaluate whether survival of older patients with severe injuries is positively associated with initial presentation to high-volume trauma hospitals. Design: Historical cohort study. Setting. 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: Patients aged 2:65 with principal injury diagnoses (ICD-9 800-959, excluding 905, 930-939, 958) admitted to hospitals or who died in emergency departments during 1999. Interventions. None. Measurements and Main Results: 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. Conclusions: Existing systems of trauma care result in similar survival for older patents With serious injuries seen first at low-volume or high-volume hospitals.