Azithromycin in early infancy and pyloric stenosis.

Pedi­atrics.  2015; 135(3):483–8 Eber­ly MD; Eide MB; Thomp­son JL; Nylund CM

BACKGROUND AND OBJECTIVE: Use of oral ery­thromycin in infants is asso­ci­at­ed with infan­tile hyper­trophic pyloric steno­sis (IHPS). The risk with azithromycin remains unknown. We eval­u­at­ed the asso­ci­a­tion between expo­sure to oral azithromycin and ery­thromycin and sub­se­quent devel­op­ment of IHPS.

METHODS: A ret­ro­spec­tive cohort study of chil­dren born between 2001 and 2012 was per­formed uti­liz­ing the mil­i­tary health sys­tem data­base. Infants pre­scribed either oral ery­thromycin or azithromycin as out­pa­tients in the first 90 days of life were eval­u­at­ed for devel­op­ment of IHPS. Spe­cif­ic diag­nos­tic and pro­ce­dur­al codes were used to iden­ti­fy cas­es of IHPS.

RESULTS: A total of 2466 of 1 074 236 chil­dren in the study peri­od devel­oped IHPS. Azithromycin expo­sure in the first 14 days of life demon­strat­ed an increased risk of IHPS (adjust­ed odds ratio [aOR], 8.26; 95% con­fi­dence inter­val [CI], 2.62–26.0); expo­sure between 15 and 42 days had an aOR of 2.98 (95% CI, 1.24–7.20). An asso­ci­a­tion between ery­thromycin and IHPS was also con­firmed. Expo­sure to ery­thromycin in the first 14 days of life had an aOR of 13.3 (95% CI, 6.80–25.9), and 15 to 42 days of life, aOR 4.10 (95% CI, 1.69–9.91). There was no asso­ci­a­tion with either macrolide between 43 and 90 days of life.

CONCLUSIONS: Inges­tion of oral azithromycin and ery­thromycin places young infants at increased risk of devel­op­ing IHPS. This asso­ci­a­tion is strongest if the expo­sure occurred in the first 2 weeks of life, but per­sists although to a less­er degree in chil­dren between 2 and 6 weeks of age.