Neonatal intensive care unit antibiotic use.

BACKGROUND AND OBJECTIVES Treatment of suspected infection is a mainstay of the daily work in the NICU. We hypothesized that NICU antibiotic prescribing practice variation correlates with rates of proven infection, necrotizing enterocolitis (NEC), mortality, inborn admission, and with NICU surgical volume and average length of stay. METHODS In a retrospective cohort study of 52,061 infants in 127 NICUs across California during 2013, we compared sample means and explored linear and nonparametric correlations, stratified by NICU level of care and lowest/highest antibiotic use rate quartiles. RESULTS Overall antibiotic use varied 40-fold, from 2.4% to 97.1% of patient-days; median = 24.5%. At all levels of care, it was independent of proven infection, NEC, surgical volume, or mortality. Fifty percent of intermediate level NICUs were in the highest antibiotic use quartile, yet most of these units reported infection rates of zero. Regional NICUs in the highest antibiotic quartile reported inborn admission rate 218% higher (0.24 vs 0.11, P = .03), and length of stay 35% longer (90.2 days vs 66.9 days, P = .03) than regional NICUs in the lowest quartile. CONCLUSIONS Forty-fold variation in NICU antibiotic prescribing practice across 127 NICUs with similar burdens of proven infection, NEC, surgical volume, and mortality indicates that a considerable portion of antibiotic use lacks clear warrant; in some NICUs, antibiotics are overused. Additional study is needed to establish appropriate use ranges and elucidate the determinants and directionality of relationships between antibiotic and other resource use.