Many patients on intravenous antibiotics often must wait 24 hours after their medications have been discontinued or until they are switched to oral antibiotics before being discharged from the hospital. This is done to protect patients from deteriorating after medications are discontinued, and to identify adverse events from oral antibiotics. However, the utility of this practice is in question, as modern antibiotics remain at therapeutic blood levels for several hours after the drug is discontinued. In addition, patients are often switched to the oral version of the same antibiotic. As a result, this practice increases costs for little or no clinical benefit. Dunn and colleagues conducted a retrospective study to evaluate whether an observation period after intravenous antibiotics are discontinued serves a clinically useful purpose.

Medical records of patients from an urban medical center who had diagnoses of cellulitis, pneumonia or urinary tract infection were reviewed over a six-month period. Patients had to be at least 18 years old and had to be admitted to one of the hospital's medical services or intensive care units. Exclusion criteria included a history of human immunodeficiency virus infection, abscess or empyema, nosocomial infection, drug-induced neutropenia and dialysis. Those included in the study had either been switched to oral antibiotics or had stopped taking antibiotics altogether.

Demographic information, admission data and comorbidities were recorded for all patients. Patients were divided into two groups: an observation group and a no-observation group. Those in the observation group were not discharged on the day their intravenous antibiotics were discontinued, while those in the no-observation group were discharged at that time. All available notes were reviewed to assess the rate of recurrence of infection or adverse reactions to oral antibiotics during the 24 hours after the intravenous antibiotics were discontinued. The two-week period after hospital discharge was also reviewed, when possible, to calculate the rate of hospital readmission for recurrent infection.

Of the 468 records reviewed, 371 were included in the analysis. A total of 308 (63 percent) were in the observation group and 63 (17 percent) were in the no-observation group. Patients in the latter group tended to be younger and less ill than those in the observation group. Three patients in the observation group experienced a recurrence, and three other patients in this group experienced adverse reactions to oral antibiotics. One patient in the no-observation group and 10 patients in the observation group were readmitted for recurrent infection.

The authors conclude that the often-used observation period after discontinuation of intravenous antibiotics is not warranted in patients with cellulitis, pneumonia or urinary tract infection. Eliminating this observation period decreases the length of hospital stay, the risk of iatrogenic illness and the risk of medication error.