Oral erythromycin prophylaxis vs watchful waiting in caring for newborns exposed to Chlamydia trachomatis.

Background: Chlamydia trachomatis exposure at birth may cause conjunctivitis or pneumonia. Until recently, a course of oral erythromycin prophylaxis was recommended for C trachomatis-exposed neonates. However, recognition of an association between erythromycin and pyloric stenosis prompted a change to a watchful waiting recommendation under which only infants who develop symptomatic C trachomatis infection are treated with oral erythromycin.

Objective: To compare erythromycin prophylaxis with watchful waiting for a hypothetical cohort of 100 000 neonates exposed to C trachomatis.

Methods: In a decision tree, potential outcomes were C trachomatis conjunctivitis, C trachomatis pneumonia (which could require inpatient or outpatient therapy), no clinical disease, and pyloric stenosis. Published data were reviewed to derive probability point estimates and ranges. Estimated charges served as outcome measures.

Results: Watchful waiting is less expensive than erythromycin prophylaxis ($15.1 million vs $28.3 million); prophylaxis prevents 5986 cases of C trachomatis pneumonia, including 1197 hospital admissions, but causes 3284 pyloric stenosis cases. (For every 30 infants given oral erythromycin prophylaxis, one additional case of pyloric stenosis would be expected to occur, and approximately 1.8 cases of C trachomatis pneumonia would be prevented.) In sensitivity analyses, if more than 3.4% of exposed neonates are hospitalized for C trachomatis pneumonia, prophylaxis becomes favored.

Conclusions: This study supports the watchful waiting recommendation for asymptomatic C trachomatis-exposed neonates. However, there are wide plausible ranges for pyloric stenosis risk after erythromycin administration and for the incidence of C trachomatis pneumonia severe enough to require hospitalization; under some combinations of these rates, prophylaxis could be favored.