Early exposure to azithromycin may increase pyloric stenosis risk

Last Updated: 2015-02-16

By Reuters Staff

NEW YORK (Reuters Health) - Exposure to azithromycin, especially during the first two weeks of life, is associated with an increased risk of infantile hypertrophic pyloric stenosis (IHPS), according to a retrospective study.

Erythromycin use in the first few weeks of life has previously been linked to the development of pyloric stenosis, but little had been known about whether azithromycin increases the risk.

Dr. Matthew D. Eberly and colleagues from F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, used data from the TRICARE Management Activity military health system database to evaluate the association between exposure to oral azithromycin in the neonatal period and the subsequent development of IHPS.

The overall incidence of IHPS was 2.29 per 1000 infants in the database. The rates were much higher among those exposed to erythromycin (8.94 per 1000), but there did not appear to be an increased incidence among those exposed to azithromycin (1.64 per 1000 overall).

Among 148 infants exposed to azithromycin in the first 14 days of life, however, the risk of IHPS was 8.26 times higher than that of other infants, according to the February 16 Pediatrics online report.

The risk was somewhat less elevated (2.98-fold) among infants exposed to azithromycin when they were 15 to 42 days old.

All eight infants exposed to azithromycin who developed IHPS were boys, as were 14 of the 17 infants who developed IHPS after exposure to erythromycin.

The numbers needed to harm in the 0- to 14-day exposure groups were 56 for azithromycin and 35 for erythromycin, and in the 15- to 42-day exposure groups were 219 for azithromycin and 142 for erythromycin.

By comparison, cephalexin exposure was not associated with the development of IHPS across all time periods.

"In an era when an increasing number of young infants are being considered for pertussis prophylaxis, practitioners must carefully weigh the risks and benefits when prescribing azithromycin, particularly to male infants in the first few weeks of life," the researchers conclude. "These infants should be monitored for signs and symptoms of pyloric stenosis for six weeks after treatment with azithromycin."

Dr. Eberly did not respond to a request for comments.

The authors report no external funding or disclosures.

SOURCE: http://bit.ly/1CAPp10

Pediatrics 2015.