Importance: Hospitals use rates from the best quartile or decile as benchmarks for quality improvement aims, but to what extent these aims are achievable is uncertain.

Objective: To determine the proportion of neonatal intensive care units (NICUs) in 2014 that achieved rates for death and major morbidities as low as the shrunken adjusted rates from the best quartile and decile in 2005 and the time it took to achieve those rates.

Design, setting, and participants: A total of 408 164 infants with a birth weight of 501 to 1500 g born from January 1, 2005, to December 31, 2014, and cared for at 756 Vermont Oxford Network member NICUs in the United States were evaluated. Logistic regression models with empirical Bayes factors were used to estimate standardized morbidity ratios for each NICU. Each ratio was multiplied by the overall network rate to calculate the 10th, 25th, 50th, 75th, and 90th percentiles of the shrunken adjusted rates for each year. The proportion in 2014 that achieved the 10th and 25th percentile rates from 2005 and the number of years it took for 75% of NICUs to achieve the 2005 rates from the best quartile were estimated.

Main outcomes and measures: Death prior to hospital discharge, infection more than 3 days after birth, severe retinopathy of prematurity, severe intraventricular hemorrhage, necrotizing enterocolitis, and chronic lung disease among infants less than 33 weeks' gestational age at birth.

Results: Of the 756 hospitals, 695 provided data for 2014. The mean unadjusted infant-level rate of death before hospital discharge decreased from 14.0% in 2005 to 10.9% in 2014. In 2014, 689 of 695 NICUs (99.1%; 95% CI, 97.4%-100.0%) achieved the 2005 shrunken adjusted rates from the best quartile for death prior to discharge, 678 of 695 (97.6%; 95% CI, 95.8%-99.6%) for late-onset infection, 558 of 681 (81.9%; 95% CI, 77.2%-86.6%) for severe retinopathy of prematurity, 611 of 693 (88.2%; 95% CI, 81.7%-97.0%) for severe intraventricular hemorrhage, 529 of 696 (76.0%; 95% CI, 71.8%-81.2%) for necrotizing enterocolitis, and 286 of 693 (41.3%; 95% CI, 36.1%-45.6%) for chronic lung disease. It took 3 years before 445 NICUs (75.0%) achieved the 2005 shrunken adjusted rate from the best quartile for death prior to discharge, 5 years to achieve the rate from the best quartile for late-onset infection, 6 years to achieve the rate from the best quartile for severe retinopathy of prematurity and severe intraventricular hemorrhage, and 8 years to achieve the rate from the best quartile for necrotizing enterocolitis.

Conclusions and relevance: From 2005 to 2014, rates of death prior to discharge and serious morbidities decreased among the NICUs in this study. Within 8 years, 75% of NICUs achieved rates of performance from the best quartile of the 2005 benchmark for all outcomes except chronic lung disease. These findings provide a novel way to quantify the magnitude and pace of improvement in neonatology.