Association Between Neonatal Intensive Care Unit Admission Rates and Illness Acuity

Abstract

IMPORTANCE Most neonates admitted to a neonatal intensive care unit (NICU) are born at gestational age (GA) of 34 weeks or more. The degree of uniformity of admission criteria for these infants is unclear, particularly at the low-acuity end of the range of conditions warranting admission.OBJECTIVES To describe variation in NICU admission rates for neonates born at GA of 34 weeks or more and examine whether such variation is associated with high illness acuity or designated facility level of care. DESIGN, SETTING, AND PARTICIPANTSCross-sectional study of 35 921 NICU inborn admissions of GA at 34 weeks or more during calendar year 2015, using a population database of inborn NICU admissions at 130 of the 149 hospitals in California with a NICU. The aggregate service population comprised 358 453 live births. The individual NICU was the unit of observation and analysis. The analysis was stratified by designated facility level of care and correlations with the percentage admissions with high illness acuity were explored. The hypothesis at the outset of the study was that inborn admission rates would correlate positively with the percentage of admissions with high illness acuity.EXPOSURES Live birth at GA of 34 weeks or more. MAIN OUTCOMES AND MEASURES Inborn NICU admission rate.RESULTS Of the total of 358 453 live births at GA of 34 weeks or more, 35 921 infants were admitted to a NICU and accounted for 79.2% of all inborn NICU admissions; 4260 (11.9%) of these admissions met high illness acuity criteria. Inborn admission rates varied 34-fold, from 1.1% to 37.7% of births (median, 9.7%; mean [SD], 10.6% [5.8%]). Percentage with high illness acuity varied 40-fold, from 2.4% to 95% (median, 11.3%; mean, 13.2% [9.9%]). Inborn admission rate correlated inversely with percentage of admissions with high illness acuity (Spearman ρ = −0.3034, P < .001). Among regional NICUs capable of caring for patients with the highest degree of illness and support needs, inborn admission rate did not significantly correlate with percentage of admissions with high illness acuity (Spearman ρ = −0.21, P = .41). CONCLUSIONS AND RELEVANCEPercentage of admissions with high illness acuity does not explain 34-fold variation in NICU inborn admission rates for neonates born at GA of 34 weeks or more. The findings are consistent with a supply-sensitive care component and invite future investigation to clarify the lower-acuity end of the range of conditions considered to warrant neonatal intensive care.

Variations in Neonatal Antibiotic Use

“…However, the numbers of intermediate NICU admissions, patient-days, and antibiotic-days did not significantly differ across years, nor were EOS rates higher than at other levels of NICUs (Table 2). Therefore, antibiotic overuse is clearest at intermediate NICUs with both a relatively high AUR and inborn admission rate, and this may support other observations 23 , 24 that reveal a component of supply-sensitive care 25 , 26 . Supply-sensitive care has little evidence base, reflecting instead available service capacity and payment systems that are used to incentivize resource use.…”

Variation in Use by NICU Types in the United States

“…In our cohort, 74% of the infants admitted were ≥34 weeks' gestational age, similar to the 80% reported in California. 10 Fifteen percent of infants ≥34 weeks' gestational age were high acuity, similar to 12% in California. 10 Ten percent of infants in our cohort stayed no more than 3 days and were discharged from the hospital.…”

“…22 Fifteen percent of infants ≥34 weeks' gestational age were high acuity. Our definition of high acuity, which was modeled after Schulman et al, 10 does not include all types of acute issues that may require NICU admission. Ziegler et al 11 identified 16 reasons, ranging from infection to brain injury to respiratory issues.…”

“…9 In California, infants ≥34 weeks' gestational age accounted for nearly 80% of all inborn neonatal intensive care admissions, with wide variation based on center type. 10 However, only 12% of those infants met highacuity illness criteria, such as assisted ventilation for at least 4 hours, bacterial infection in the first 3 days from birth, suspected encephalopathy or perinatal asphyxia, or active therapeutic hypothermia; and the proportion of high-acuity infants varied at the center level from 2.4% to 95%. 10 At a group of 19 hospitals, the percentage of infants 35 to 42 weeks' gestation admitted to a NICU without a prespecified, identifiable high-acuity cause ranged from 0% to 59%; such infants accounted for 9.1% of total NICU days with lower lengths of stay than other infants.…”

“…10 However, only 12% of those infants met highacuity illness criteria, such as assisted ventilation for at least 4 hours, bacterial infection in the first 3 days from birth, suspected encephalopathy or perinatal asphyxia, or active therapeutic hypothermia; and the proportion of high-acuity infants varied at the center level from 2.4% to 95%. 10 At a group of 19 hospitals, the percentage of infants 35 to 42 weeks' gestation admitted to a NICU without a prespecified, identifiable high-acuity cause ranged from 0% to 59%; such infants accounted for 9.1% of total NICU days with lower lengths of stay than other infants. 11 As hospitals and insurers work to control costs and improve the value of care, 12 use of health care resources is under increased scrutiny.…”