Baltimore, MD—Adverse effects occurred in one-fifth of patients prescribed antibiotics at a major teaching hospital, a new study reveals.

Even worse, according to the article published in JAMA Internal Medicine, about 20% of those patients didn’t need to be taking antibiotics at all.

“Too often, clinicians prescribe antibiotics even if they have a low suspicion for a bacterial infection, thinking that even if antibiotics may not be necessary, they are probably not harmful,” explained lead author Pranita Tamma, MD, MHS, assistant professor of pediatrics and director of the Pediatric Antimicrobial Stewardship Program at The Johns Hopkins Hospital. “But that is not always the case. Antibiotics have the potential to cause real harm to patients. Each time we think to prescribe an antibiotic, we need to pause and ask ourselves, ‘Does this patient really need an antibiotic?’”

With that, Tamma adds, “If the patient develops an antibiotic-associated adverse reaction, even though that is, of course, unfortunate, we should be able to take some comfort in knowing that at least the antibiotic was truly necessary.”

For the study, researchers evaluated the electronic medical records of 1,488 adults admitted to the general medicine services at The Johns Hopkins Hospital between September 2013 and June 2014. All of the patients, who were admitted for a variety of reasons ranging from trauma to chronic disease, received at least 24 hours of antibiotic treatment.

Over 30 days of follow-up, the patients were monitored to determine how many had an adverse reaction to antibiotics and to identify ways to avoid the undesired effects by eliminating unnecessary antibiotic use.

Results indicate that 298 of the patients, 20%, experienced at least one antibiotic-associated adverse drug event (ADE). The researchers also determined that 56 (20%) nonclinically indicated antibiotic regimens were associated with an ADE, including in seven patients who developed dangerous Clostridium difficile (C diff) infection.

Study authors calculate that every additional 10 days of antibiotic therapy was linked to a 3% increased risk of an ADE, and that the type of antibiotic mattered. Overall, the most common ADEs were gastrointestinal, renal, and hematologic abnormalities, accounting for 78 (42%), 45 (24%), and 28 (15%) 30-day ADEs, respectively.

Patients were observed for up to 90 days to track the development of C diff, which occurred in 4%, and multidrug-resistant infections, which occurred in 6%.

No increased mortality was associated with the use of antibiotics in this study, but the authors point out that, as a result of adverse effects:
• 24% of patients had prolonged hospital stays
• 3% of patients experienced additional hospital admissions
• 9% of patients required additional emergency department or clinic visits
• 61% of patients needed additional diagnostic tests

And those statistics might be even higher at other facilities, the study adds, because The Johns Hopkins Hospital has an active antibiotic stewardship program to reduce antibiotic overuse.

“In general, we would expect our hospital to have lower numbers of antibiotic-associated side effects than at hospitals without antibiotic stewardship programs because our stewardship team assists healthcare providers with optimizing the administration of antibiotics, and we tend to recommend targeted therapies for shorter periods of time,” noted coauthor Sara Cosgrove, MD, MS, professor of medicine and director of the antimicrobial stewardship program at The Johns Hopkins Hospital.

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