Early versus delayed IV-to-oral antibiotic transition: clinical deterioration after oral switch and variation across regimen pathways.

OBJECTIVE

To assess associations of delayed (>72 hours) versus early (≤72 hours) IV-to-oral antibiotic switching with 7-day switch failure and adjusted post-switch clinical outcomes in hospitalized adults.

METHODS

Adult admissions receiving IV antibiotics followed by oral therapy during the same hospitalization were included. Early switch occurred within 72 hours of admission and delayed switch after 72 hours. Switch failure was defined as IV restart or antibiotic escalation within 7 days. Adjusted models assessed post-switch length of stay (LOS), in-hospital mortality, ICU transfer, and vasopressor initiation within 7 days.

RESULTS

Among 3898 admissions, 2002 had delayed and 1896 early switches. Switch failure within 7 days occurred in 14.7% versus 6.4%, respectively. Delayed switching was associated with longer post-switch LOS (adjusted ratio 1.94, 95% CI 1.70-2.22), higher in-hospital mortality (aOR 2.29, 1.21-4.34), vasopressor initiation (aOR 9.68, 2.28-41.04), and IV restart within 7 days (aOR 2.24, 1.79-2.81). ICU transfer showed no clear adjusted difference.

CONCLUSION

Delayed switching after 72 hours was associated with more 7-day events and worse adjusted outcomes. However, switch timing is a surrogate for underlying clinical status and should not be interpreted as a direct measure of disease severity or cause of deterioration. Interpretation should consider physiologic stability, infection severity, source control, microbiology, and the feasibility of oral treatment. .