Objective:

L-arginine supplemented immunonutrition (IM) enteral formulas have been designed to optimize outcomes in critically ill patients, and routine use is suggested post-operatively in the surgical intensive care unit (ICU). The objective was to compare health outcomes between different IM formulas.

Methods:

Premier’s PINC™ Healthcare Database was reviewed retrospectively from Oct 2015 – Feb 2019 for patients with an ICU stay and who had at least 3 days exclusive use of either higher L-arginine (18.7 g/L) formula (HAF), or lower L-arginine (11 g/L) formula (LAF). Patient demographics, clinical characteristics, co-morbidities, severity of illness, and outcomes were abstracted. Multivariable generalized linear model regression was used to check associations between formulas and ICU length of stay (LOS).

Results:

3,284 patients (73% surgical) were included from 21 hospitals, with 2,525 receiving HAF and 759 LAF.

Median ICU LOS was shorter for HAF compared to LAF patients (10 vs. 12 days; p<0.001). Inpatient mortality (19.4%) did not differ between groups, but 30-day all-cause readmission rate was lower in HAF compared to LAF patients (11.6% vs. 15.3%, p=0.01). Also, patients receiving HAF had less rectal catheterization (9% vs. 19%; p<0.001).

After adjusting for demographics, visit, severity of illness, and clinical characteristics, associated ICU LOS for patients in the HAF group was 11% lower [exponentiated coefficient = 0.89 (95% CI: 0.84, 0.94; p<0.001)] compared to patients in the LAF group. Adjusted mean ICU LOS was 9.4 days (95% CI: 8.9, 10.0 days) for the HAF group compared to 10.6 days (95% CI: 9.9, 11.3 days) for the LAF group (p < 0.001).

Conclusion:

Despite formulas being isocaloric/isoproteic, HAF use was associated with significantly reduced ICU LOS, compared to LAF. This demonstrates the potential role of higher L-arginine supplemented IM in improving health outcomes and resource utilization in critically ill patients.