Monday, July 9, 2018

Minimizing adverse effects from antibiotics: short duration + narrow spectrum

- Jennifer Middleton, MD, MPH

Adverse effects are not uncommon with antibiotics, and two recent POEMs (Patient Oriented Evidence that Matters) in AFP review strategies to minimize them. The first POEM found that shorter courses of antibiotics are equivalent to longer courses for several common outpatient infections. The 2nd POEM found that, for outpatient respiratory tract infections in children, narrow-spectrum antibiotics have a lower risk of adverse effects compared to broad-spectrum antibiotics with equivalent treatment efficacy.

The first POEM is a systematic overview of 9 systematic reviews comparing antibiotic treatment durations for urinary tract infection (UTI), acute pyelonephritis, sinusitis, and community-acquired pneumonia (CAP) in adults, and strep pharyngitis, CAP, UTI, and acute otitis media (AOM) in children. They found that:

AOM (children): 7 or less days =  more than 7 days
CAP (children): 3 days = 5 days
CAP (adults): 7 or less days = more than 7 days
Strep pharyngitis (children): 5-7 days = 10 days
Sinusitis (adults): 3-7 days = 6-10 days
UTI (children): 2-4 days =  7-14 days
UTI (non-pregnant, premenopausal women): 3 days = 5 or more days
UTI (older women): 3-6 days = 7-14 days
The authors found a reduced risk of adverse events for patients treated with shorter durations for AOM, sinusitis, and younger women with UTI; they found no difference among patients with pharyngitis, pyelonephritis, or older women with UTI. Adverse event data was not available for patients treated for CAP or children with UTI.

The 2nd POEM included both a large retrospective cohort arm (over 30,000 children) that reviewed outcomes of children with sinusitis, AOM, or strep pharyngitis diagnoses and a prospective cohort arm (almost 2500 children) examining the same conditions. The findings of the retrospective arm and the prospective arm concurred: broad-spectrum antibiotics (amoxicillin/clavulantate, cephalosporins, macrolides) offered no treatment benefit over narrow-spectrum antibiotics (penicillin, amoxicillin) but did increase the rate of reported adverse effects. The retrospective cohort only reported adverse event rates as documented in the medical record, but the prospective cohort included data gathering of adverse events from parents. The prospective cohort had a much higher rate (10.3 times higher) of adverse effects reported by parents, suggesting that many patients and/or their parents are not reporting these events to physicians.

It's possible that some of the patients who received antibiotics in these studies did not need them at all, thus explaining the lack of benefit in longer antibiotic treatment durations; for example, most cases of acute bacterial sinusitis will resolve without antibiotics (consider offering an intranasal corticosteroid instead), and deferring antibiotics for AOM in children over the age of 2 years with non-severe symptoms is a Choosing Wisely recommendation. Determining which patient needs an antibiotic is not always clear, either; Centor scoring can assist with pharyngitis, but, as Dr. Lin reviewed last week on the blog, procalcitonin levels may not distinguish CAP from lower respiratory tract infections that don't improve with antibiotics (such as bronchitis).

Limiting antibiotic overuse benefits patients and communitiesAFP's Choosing Wisely tool facilitates quick review of these recommendations, and there are also AFP By Topics on Pneumonia, Respiratory Tract Infections, and Urinary Tract Infections/Dysuria that include resources on diagnosis and treatment. 

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