BACKGROUND:

The success of neonatal intensive care in improving outcomes for critically ill neonates led to rapid growth of NICU use in the United States, despite a relatively stable birth cohort. Less is known about NICU use among late-preterm and term infants, although recent studies have observed wide variation in their care patterns. In this study, we measure special care days (SCDs) (intermediate or intensive), length of stay, and readmission rates among low-risk neonates across regions within 2 states.

METHODS:

In this retrospective cohort study, we analyzed data from Massachusetts (all payer claims) and Texas (BlueCross BlueShield) from 2009 to 2012. A low-risk cohort was defined by identifying newborns with diagnostic codes indicating a gestational age ≥35 weeks and birth weight ≥1500 g and excluding infants with diagnoses and procedures generally necessitating nonroutine care. Outcomes were measured across neonatal intensive care regions by diagnosis and payer type.

RESULTS:

We identified 255 311 low-risk newborns. SCD use varied nearly sixfold across neonatal intensive care regions. Use was highest among commercially insured Texas infants (8.42 per 100), followed by Medicaid-insured Massachusetts infants (6.67 per 100) and commercially insured Massachusetts infants (5.15 per 100). Coefficients of variation indicated high variation within each payer-specific cohort and moderate to high variation across each condition. No consistent relationship between regional SCD use and 30-day readmissions was identified.

CONCLUSIONS:

Use of NICU services varied widely across regions in this cohort of low-risk infants. Further investigation is needed to delineate outcomes associated with patterns of care received by this population.

Since the inception of neonatal intensive care, newborn morbidity and mortality in the perinatal period has decreased more than fourfold.1  In a large body of research, researchers have described the success of neonatal intensive care in improving outcomes, particularly for the premature and those with severe medical or surgical problems.1,2  The neonatology community’s commitment to data-driven initiatives continues to improve health outcomes for severely ill infants.3,4 

These successes led to rapid growth in NICU capacity across the United States, despite a relatively stable birth cohort. Between 1995 and 2013, the number of NICU beds per very low birth weight infant increased by 66%, whereas the number of very low birth weight newborns per neonatologist declined from 23 in 1996 to 14 in 2013.5  Mirroring these capacity trends, results of ecent studies support continued increases in NICU use across all birth weights (BWs) and gestational ages (GAs) but, particularly, for larger infants; in 2012, infants born at <1500 g composed only 14% of NICU admissions.6  Studies from California and the Vermont Oxford Network have revealed similar findings.7,8 

Higher NICU use in near-term and normal BW infants has raised questions regarding the possibility of NICU overuse for some newborns.6,810  Research among this population is increasing; however, there are still relatively few studies in which researchers examine variation in care and outcomes among newborns with lower illness risk,7,8,1014  and fewer are population-based and examine NICU use.1012,14  Although some late-preterm and term infants require intensive care, existing evidence suggests illness acuity does not fully explain variation in care among these infants.8,11,12  Unnecessary NICU use has the potential to increase health care costs,1517  subject families to stress,1820  and put infants at risk for iatrogenic conditions.21,22  It is, therefore, important to understand patterns of NICU care among lower risk populations.

In this study, we extend previous research by examining regional variation of NICU care in a low-risk newborn population from 2 diverse states. Within payer-specific cohorts, we also measured variation in NICU use for 6 diagnoses thought to be associated with varying care practices.2328  In secondary analyses, we modeled the association of observed regional newborn care patterns with 30-day all-hospital readmission rates to test the hypothesis that lower intensity and/or duration of care is associated with a higher regional readmission risk.

In this population-based retrospective cohort study, we analyzed data from Massachusetts (all payer claims) and Texas (BlueCross BlueShield claims) from 2009 to 2012. These populations were selected on the basis of data availability to our research team. A low-risk neonatal cohort was defined by using codes from facility and professional claims. A multidisciplinary research group including newborn providers (pediatric hospitalists and newborn nursery attending physicians and neonatologists) and health services researchers reviewed all International Classification of Diseases, Ninth Revision (ICD-9) codes from 2010 to identify those applicable to newborns. Codes indicating vaginal or cesarean deliveries without mention of GA and those specific to births with a GA ≥35 weeks were included, whereas newborns with a GA <35 weeks or BW <1500 g were excluded. We excluded infants with conditions deemed to generally require care outside a well-newborn nursery (eg, those suggestive of critical illnesses or diagnoses typically requiring surgical intervention). Disagreements regarding inclusion and exclusion codes were resolved through consensus, with a goal of identifying as specific a low-risk cohort as possible (Supplemental Table 5). The newborn inpatient episode was defined as beginning at birth, continuing through all inpatient care sites, and ending with discharge.

Diagnostic subcohorts focused on conditions for which there is lack of consensus surrounding the level of care, including jaundice and hyperbilirubinemia, transient tachypnea of the newborn, observation for suspected sepsis and sepsis, hypoglycemia, hypothermia, and neonatal abstinence syndrome (NAS). Inclusion in a subcohort was based on presence of a diagnostic code corresponding to one of these diagnoses in any diagnostic field within facility or professional claims (Supplemental Table 6). Cohorts were independently defined, and infants could be included in multiple subcohorts.

Neonatal intensive care regions (NICRs) were defined for the 2 states by using similar methods. For Massachusetts, hospital service areas (n = 66) developed for the Dartmouth Atlas of Children’s Health Care in Northern New England were assigned to regions on the basis of maternal travel of all newborns to hospitals providing neonatal intensive care.29  In Texas, counties (n = 254) were similarly assigned, initially for Medicaid newborns, as previously described.11  All NICRs included at least 1 level 3 (NICU) or 4 (regional NICU) unit.30  The localization indices (ie, percent of newborn special care days [SCDs] delivered within NICR of maternal residence) of study Massachusetts newborns ranged from 48% to 80% (overall: 64%); the range for Texas newborns was 53% to 97% (overall: 89%). There were 7 NICRs in Massachusetts and 21 NICRs in Texas (Table 1).

TABLE 1

Low-risk Study Population Characteristics

n%
Total live births 255 311 100 
Sex, male 112 697 44.1 
State and payer type   
 Massachusetts Medicaid 55 839 21.9 
 Massachusetts commercial 132 673 52.0 
 Texas commercial 66 799 26.2 
NICRs   
 Massachusetts   
  Beverly 3876 1.5 
  Boston 124 569 48.8 
  Fall River 3684 1.4 
  New Bedford 4356 1.7 
  South Weymouth 9167 3.6 
  Springfield 21 862 8.6 
  Worcester 20 998 8.2 
 Texas   
  Abilene 686 0.3 
  Amarillo 1094 0.4 
  Austin 5720 2.2 
  Beaumont 1163 0.5 
  Brownsville 535 0.2 
  College Station 1322 0.5 
  Corpus Christi 1156 0.5 
  Dallas 12 996 5.1 
  Denton 2705 1.1 
  El Paso 774 0.3 
  Fort Worth 8915 3.5 
  Houston 15 188 5.9 
  Laredo 683 0.3 
  Longview 1575 0.6 
  Lubbock 1253 0.5 
  McAllen 1326 0.5 
  Odessa 2383 0.9 
  San Antonio 4531 1.8 
  Temple 1215 0.5 
  Tyler 1038 0.4 
  Victoria 541 0.2 
Inclusion codea   
 Single liveborn in hospital without mention of cesarean delivery 179 080 70.1 
 Single liveborn in hospital delivered by cesarean delivery 82 954 32.5 
 35–36 weeks’ gestation completed 10 284 4.0 
 ≥37 weeks' gestation completed 18 359 7.2 
 Exceptionally large infant, BW >4500 g 1315 0.5 
 Other heavy-for-dates infants 15 151 5.9 
 Late infant, not heavy-for-dates 5921 2.3 
 Postterm infant, 40–42 wk 5832 2.3 
 Prolonged gestation of infant, >42 wk; NOS 96 0.04 
Diagnosisb   
 Hyperbilirubinemia 61 788 24.2 
 Rule out sepsis 15 832 6.2 
 Tachypnea 7705 3.0 
 Hypothermia 3661 1.4 
 Hypoglycemia 3696 1.4 
 NAS 1537 0.6 
Inpatient mortality 37 0.01 
n%
Total live births 255 311 100 
Sex, male 112 697 44.1 
State and payer type   
 Massachusetts Medicaid 55 839 21.9 
 Massachusetts commercial 132 673 52.0 
 Texas commercial 66 799 26.2 
NICRs   
 Massachusetts   
  Beverly 3876 1.5 
  Boston 124 569 48.8 
  Fall River 3684 1.4 
  New Bedford 4356 1.7 
  South Weymouth 9167 3.6 
  Springfield 21 862 8.6 
  Worcester 20 998 8.2 
 Texas   
  Abilene 686 0.3 
  Amarillo 1094 0.4 
  Austin 5720 2.2 
  Beaumont 1163 0.5 
  Brownsville 535 0.2 
  College Station 1322 0.5 
  Corpus Christi 1156 0.5 
  Dallas 12 996 5.1 
  Denton 2705 1.1 
  El Paso 774 0.3 
  Fort Worth 8915 3.5 
  Houston 15 188 5.9 
  Laredo 683 0.3 
  Longview 1575 0.6 
  Lubbock 1253 0.5 
  McAllen 1326 0.5 
  Odessa 2383 0.9 
  San Antonio 4531 1.8 
  Temple 1215 0.5 
  Tyler 1038 0.4 
  Victoria 541 0.2 
Inclusion codea   
 Single liveborn in hospital without mention of cesarean delivery 179 080 70.1 
 Single liveborn in hospital delivered by cesarean delivery 82 954 32.5 
 35–36 weeks’ gestation completed 10 284 4.0 
 ≥37 weeks' gestation completed 18 359 7.2 
 Exceptionally large infant, BW >4500 g 1315 0.5 
 Other heavy-for-dates infants 15 151 5.9 
 Late infant, not heavy-for-dates 5921 2.3 
 Postterm infant, 40–42 wk 5832 2.3 
 Prolonged gestation of infant, >42 wk; NOS 96 0.04 
Diagnosisb   
 Hyperbilirubinemia 61 788 24.2 
 Rule out sepsis 15 832 6.2 
 Tachypnea 7705 3.0 
 Hypothermia 3661 1.4 
 Hypoglycemia 3696 1.4 
 NAS 1537 0.6 
Inpatient mortality 37 0.01 

NOS, not otherwise specified.

a

Infants may have >1 associated inclusion code.

b

Not all infants in the cohort received one of these diagnostic codes. Infants could be included in >1 diagnostic cohort.

The primary outcome measure was the rate of SCDs per 100 infants by NICR. SCDs were defined as days with a claim for intermediate or intensive facility (revenue) code or professional (Current Procedural Technology) code. These codes are derived from provider billing and are not dictated by physical bed location (eg, an infant located in a normal newborn nursery could receive an intermediate care day, as could an infant located in a NICU, depending on provider billing). Revenue codes 172 to 175 and Current Procedural Technology codes 99477 to 99480 indicated an SCD. When multiple codes occurred for a single day, the day was classified by the highest level code.

SCDs were analyzed in aggregate and by level (intermediate or intensive). Secondary outcome measures included mean length of stay (LOS) during the inpatient episode, number of SCDs for patients with any SCDs, and percent 30-day all-hospital readmission by NICR. Variation was measured across NICRs within each state. Massachusetts data were indirectly adjusted by payer mix (Medicaid or commercial) for primary analyses; variation within each payer-specific cohort was also analyzed for the full population and diagnostic subcohorts.

Variation across NICRs was measured with the coefficient of variation (CV), defined as the SD divided by the mean times 100. Generally, a CV <10 is considered indicative of low variation, 10 to 19 as moderate, and ≥20 as high.31,32  The association between use measures was tested with weighted Pearson’s correlation. The relationship between regional payer-adjusted 30-day readmission rates and overall adjusted SCD use and LOS measures was assessed with weighted (analytic weights by using the number of cohort members) linear models, with state of residence as a covariate.

This study was approved by the Committee for the Protection of Human Subjects at Dartmouth College.

255 311 newborns met the criteria for this low-risk cohort (73.8% from MA and 26.2% from TX). 33% had diagnostic codes indicating cesarean delivery, and 4% had codes indicating late-preterm gestation. Hyperbilirubinemia was the most common of studied conditions (24.2% of infants; Table 1).

In Massachusetts, the mean payer-adjusted rate of SCDs across NICRs was 5.56 days per 100 infants, with a range across NICRs of 3.82 to 8.91 (varying nearly 2.5-fold; Table 2). Payer-adjusted intermediate SCD rates were higher than intensive SCD rates in all Massachusetts NICRs; the percentage of payer-adjusted SCD use billed as intensive ranged from 8% to 32% across Massachusetts NICRs (fourfold variation; Fig 1). In payer-specific analyses, CVs for all SCD measures were high. The CV for overall SCDs was 33 in the Medicaid cohort and 27 in the commercial cohort; CVs were higher for intensive and intermediate days in both cohorts (Table 3). Across NICRs, there was a high correlation between commercial and Medicaid SCD use (Pearson’s r: 0.8; P = .03). The mean payer-adjusted LOS across NICRs for all infants was 2.65 days (range: 2.43–3.01); the mean payer-adjusted LOS for infants with at least one SCD was 5.36 (range: 5.03–7.32). Thirty-day readmission rates ranged across NICRs from 1.47% to 1.87% (mean: 1.74%; Table 2).

TABLE 2

SCD Use, LOS in Days, and Readmission Rates by NICR, Adjusted by Payer Mix

NICRAny SCD, Rate of SCDs per 100 Infants (95% CI)LOS (95% CI)30-d Readmission Rate, % (95% CI)
Average LOS for All InfantsAverage LOS for Infants With an SCDAverage LOS for Infants Without an SCD
Massachusetts 5.56 (5.46–5.66) 2.65 (2.55–2.57) 5.36 (5.32–5.41) 2.49 (2.48–2.50) 1.74 (1.68–1.80) 
 Beverly 8.91 (7.96–11.15) 2.77 (2.25–3.61) 5.12 (4.40–6.80) 2.55 (2.05–3.33) 1.77 (1.33–2.35) 
 Boston 5.49 (5.36–5.80) 2.65 (2.56–2.80) 5.07 (4.94–5.36) 2.51 (2.42–2.65) 1.72 (1.65–1.82) 
 Fall River 6.58 (5.77–8.49) 3.01 (2.44–3.94) 7.32 (6.46–9.32) 2.66 (2.12–3.51) 1.47 (1.11–1.94) 
 New Bedford 6.35 (5.62–8.08) 2.92 (2.40–6.68) 6.68 (5.92–8.43) 2.63 (2.14–3.41) 2.02 (1.63–2.52) 
 South Weymouth 5.14 (5.67–6.25) 2.76 (2.43–6.06) 6.06 (5.55–7.25) 2.58 (2.26–3.10) 2.02 (1.71–2.43) 
 Springfield 6.86 (6.51–7.66) 2.71 (2.49–3.07) 6.04 (5.71–6.78) 2.46 (2.24–2.79) 1.58 (1.43–1.78) 
 Worcester 3.82 (3.56–4.44) 2.43 (2.22–2.77) 5.03 (4.72–5.73) 2.33 (2.12–2.65) 1.87 (1.69–2.12) 
Texas 8.42 (8.21 8.63) 2.33 (2.32–2.35) 4.75 (4.65–4.86) 2.11 (2.11–2.12) 2.33 (2.21–2.44) 
 Abilene 11.22 (8.86–13.59) 2.15 (2.03–2.27) 5.12 (4.48–5.76) 1.77 (1.72–1.83) 1.31 (0.46–2.17) 
 Amarillo 6.22 (4.78–7.65) 2.22 (2.11–2.33) 6.88 (5.63–8.13) 1.91 (1.87–1.95) 2.19 (1.32–3.06) 
 Austin 5.38 (4.80–5.97) 2.45 (2.41–2.49) 5.38 (4.78–5.99) 2.29 (2.27–2.31) 2.55 (2.14–2.96) 
 Beaumont 15.13 (13.07–17.20) 2.76 (2.66–2.86) 5.17 (4.67–5.67) 2.33 (2.29–2.37) 2.24 (1.38–3.09) 
 Brownsville 6.73 (4.60–8.86) 1.83 (1.73–1.93) 4.67 (3.78–5.56) 1.62 (1.57–1.68) 2.62 (1.26–3.97) 
 College Station 10.36 (8.72–12.01) 2.25 (2.19–2.32) 3.98 (3.60–4.35) 2.05 (2.01–2.10) 4.39 (3.28–5.49) 
 Corpus Christi 8.56 (6.95–10.18) 2.06 (1.97–2.15) 5.08 (4.38–5.79) 1.78 (1.73–1.83) 2.16 (1.32–3.00) 
 Dallas 8.19 (7.72–8.67) 2.51 (2.48–2.54) 4.83 (4.57–5.09) 2.30 (2.28–2.32) 1.86 (1.63–2.09) 
 Denton 6.58 (5.65–7.52) 2.38 (2.33–2.42) 4.20 (3.77–4.64) 2.25 (2.22–2.28) 1.89 (1.37–2.40) 
 El Paso 8.27 (6.32–10.21) 2.19 (2.01–2.37) 7.95 (6.42–9.49) 1.67 (1.63–1.71) 2.71 (1.57–3.86) 
 Fort Worth 6.01 (5.52–6.51) 2.20 (2.18–2.23) 4.90 (4.60–5.19) 2.03 (2.02–2.05) 2.12 (1.82–2.42) 
 Houston 8.89 (8.44–9.34) 2.43 (2.41–2.46) 4.75 (4.53–4.97) 2.21 (2.20–2.22) 2.52 (2.27–2.76) 
 Laredo 6.00 (4.22–7.79) 1.99 (1.88–2.10) 6.00 (4.99–7.01) 1.73 (1.69–1.78) 2.93 (1.66–4.20) 
 Longview 8.83 (7.42–10.23) 2.04 (1.99–2.09) 3.36 (2.95–3.77) 1.92 (1.88–1.95) 3.81 (2.86–4.76) 
 Lubbock 6.54 (5.17–7.92) 2.28 (2.19–2.37) 4.83 (3.71–5.95) 2.11 (2.06–2.15) 1.92 (1.16–2.68) 
 McAllen 7.47 (6.05–8.88) 1.91 (1.83–1.98) 5.18 (4.55–5.81) 1.64 (1.61–1.68) 1.36 (0.73–1.98) 
 Odessa 22.58 (20.90–24.26) 2.04 (1.99–2.10) 3.01 (2.80–3.22) 1.76 (1.73–1.79) 2.22 (1.63–2.82) 
 San Antonio 9.36 (8.51–10.21) 2.31 (2.25–2.36) 5.44 (4.98–5.90) 1.98 (1.96–2.01) 2.30 (1.86–2.73) 
 Temple 6.67 (5.26–8.07) 2.13 (2.04–2.23) 6.23 (5.36–7.11) 1.84 (1.80–1.88) 3.05 (2.08–4.01) 
 Tyler 8.19 (6.52–9.86) 2.05 (1.93–2.16) 5.34 (4.31–6.37) 1.75 (1.70–1.80) 3.37 (2.27–4.47) 
 Victoria 7.76 (5.50–10.03) 2.00 (1.90–2.11) 3.74 (3.16–4.32) 1.86 (1.76–1.95) 3.14 (1.67–4.62) 
NICRAny SCD, Rate of SCDs per 100 Infants (95% CI)LOS (95% CI)30-d Readmission Rate, % (95% CI)
Average LOS for All InfantsAverage LOS for Infants With an SCDAverage LOS for Infants Without an SCD
Massachusetts 5.56 (5.46–5.66) 2.65 (2.55–2.57) 5.36 (5.32–5.41) 2.49 (2.48–2.50) 1.74 (1.68–1.80) 
 Beverly 8.91 (7.96–11.15) 2.77 (2.25–3.61) 5.12 (4.40–6.80) 2.55 (2.05–3.33) 1.77 (1.33–2.35) 
 Boston 5.49 (5.36–5.80) 2.65 (2.56–2.80) 5.07 (4.94–5.36) 2.51 (2.42–2.65) 1.72 (1.65–1.82) 
 Fall River 6.58 (5.77–8.49) 3.01 (2.44–3.94) 7.32 (6.46–9.32) 2.66 (2.12–3.51) 1.47 (1.11–1.94) 
 New Bedford 6.35 (5.62–8.08) 2.92 (2.40–6.68) 6.68 (5.92–8.43) 2.63 (2.14–3.41) 2.02 (1.63–2.52) 
 South Weymouth 5.14 (5.67–6.25) 2.76 (2.43–6.06) 6.06 (5.55–7.25) 2.58 (2.26–3.10) 2.02 (1.71–2.43) 
 Springfield 6.86 (6.51–7.66) 2.71 (2.49–3.07) 6.04 (5.71–6.78) 2.46 (2.24–2.79) 1.58 (1.43–1.78) 
 Worcester 3.82 (3.56–4.44) 2.43 (2.22–2.77) 5.03 (4.72–5.73) 2.33 (2.12–2.65) 1.87 (1.69–2.12) 
Texas 8.42 (8.21 8.63) 2.33 (2.32–2.35) 4.75 (4.65–4.86) 2.11 (2.11–2.12) 2.33 (2.21–2.44) 
 Abilene 11.22 (8.86–13.59) 2.15 (2.03–2.27) 5.12 (4.48–5.76) 1.77 (1.72–1.83) 1.31 (0.46–2.17) 
 Amarillo 6.22 (4.78–7.65) 2.22 (2.11–2.33) 6.88 (5.63–8.13) 1.91 (1.87–1.95) 2.19 (1.32–3.06) 
 Austin 5.38 (4.80–5.97) 2.45 (2.41–2.49) 5.38 (4.78–5.99) 2.29 (2.27–2.31) 2.55 (2.14–2.96) 
 Beaumont 15.13 (13.07–17.20) 2.76 (2.66–2.86) 5.17 (4.67–5.67) 2.33 (2.29–2.37) 2.24 (1.38–3.09) 
 Brownsville 6.73 (4.60–8.86) 1.83 (1.73–1.93) 4.67 (3.78–5.56) 1.62 (1.57–1.68) 2.62 (1.26–3.97) 
 College Station 10.36 (8.72–12.01) 2.25 (2.19–2.32) 3.98 (3.60–4.35) 2.05 (2.01–2.10) 4.39 (3.28–5.49) 
 Corpus Christi 8.56 (6.95–10.18) 2.06 (1.97–2.15) 5.08 (4.38–5.79) 1.78 (1.73–1.83) 2.16 (1.32–3.00) 
 Dallas 8.19 (7.72–8.67) 2.51 (2.48–2.54) 4.83 (4.57–5.09) 2.30 (2.28–2.32) 1.86 (1.63–2.09) 
 Denton 6.58 (5.65–7.52) 2.38 (2.33–2.42) 4.20 (3.77–4.64) 2.25 (2.22–2.28) 1.89 (1.37–2.40) 
 El Paso 8.27 (6.32–10.21) 2.19 (2.01–2.37) 7.95 (6.42–9.49) 1.67 (1.63–1.71) 2.71 (1.57–3.86) 
 Fort Worth 6.01 (5.52–6.51) 2.20 (2.18–2.23) 4.90 (4.60–5.19) 2.03 (2.02–2.05) 2.12 (1.82–2.42) 
 Houston 8.89 (8.44–9.34) 2.43 (2.41–2.46) 4.75 (4.53–4.97) 2.21 (2.20–2.22) 2.52 (2.27–2.76) 
 Laredo 6.00 (4.22–7.79) 1.99 (1.88–2.10) 6.00 (4.99–7.01) 1.73 (1.69–1.78) 2.93 (1.66–4.20) 
 Longview 8.83 (7.42–10.23) 2.04 (1.99–2.09) 3.36 (2.95–3.77) 1.92 (1.88–1.95) 3.81 (2.86–4.76) 
 Lubbock 6.54 (5.17–7.92) 2.28 (2.19–2.37) 4.83 (3.71–5.95) 2.11 (2.06–2.15) 1.92 (1.16–2.68) 
 McAllen 7.47 (6.05–8.88) 1.91 (1.83–1.98) 5.18 (4.55–5.81) 1.64 (1.61–1.68) 1.36 (0.73–1.98) 
 Odessa 22.58 (20.90–24.26) 2.04 (1.99–2.10) 3.01 (2.80–3.22) 1.76 (1.73–1.79) 2.22 (1.63–2.82) 
 San Antonio 9.36 (8.51–10.21) 2.31 (2.25–2.36) 5.44 (4.98–5.90) 1.98 (1.96–2.01) 2.30 (1.86–2.73) 
 Temple 6.67 (5.26–8.07) 2.13 (2.04–2.23) 6.23 (5.36–7.11) 1.84 (1.80–1.88) 3.05 (2.08–4.01) 
 Tyler 8.19 (6.52–9.86) 2.05 (1.93–2.16) 5.34 (4.31–6.37) 1.75 (1.70–1.80) 3.37 (2.27–4.47) 
 Victoria 7.76 (5.50–10.03) 2.00 (1.90–2.11) 3.74 (3.16–4.32) 1.86 (1.76–1.95) 3.14 (1.67–4.62) 

Massachusetts data only were adjusted for payer mix.

FIGURE 1

Rate of SCDs by Type Across NICRs. Massachusetts rates are payer-adjusted.

FIGURE 1

Rate of SCDs by Type Across NICRs. Massachusetts rates are payer-adjusted.

Close modal
TABLE 3

Variation in SCD Use, LOS, and 30-Day Readmission Rate Across NICRs by State and by Payer Type

MassachusettsTexas
MedicaidCVCommercialCVCommercialCV
SCD       
 Rate of SCDs per 100 6.67 33 5.15 27 8.42 44 
 Rate of intensive SCDs per 100 2.18 45 1.35 49 1.88 81 
 Rate of intermediate SCDs per 100 4.49 43 3.80 37 6.54 66 
LOS, d       
 Average LOS 2.35 12 2.69 2.34 10 
 Average LOS for infants with SCDs 6.15 21 5.06 11 4.75 22 
 Average LOS for infants without SCDs 2.09 2.56 2.11 12 
Readmission rate, 30 d 2.39 1.20 2.33 30 
MassachusettsTexas
MedicaidCVCommercialCVCommercialCV
SCD       
 Rate of SCDs per 100 6.67 33 5.15 27 8.42 44 
 Rate of intensive SCDs per 100 2.18 45 1.35 49 1.88 81 
 Rate of intermediate SCDs per 100 4.49 43 3.80 37 6.54 66 
LOS, d       
 Average LOS 2.35 12 2.69 2.34 10 
 Average LOS for infants with SCDs 6.15 21 5.06 11 4.75 22 
 Average LOS for infants without SCDs 2.09 2.56 2.11 12 
Readmission rate, 30 d 2.39 1.20 2.33 30 

The CV is the SD divided by the mean multiplied by 100.

In Texas, the mean rate of SCDs across NICRs was 8.42 days per 100 (range: 5.38–22.58, varying more than fourfold; Table 2). Intermediate SCD use was greater than intensive in 16 of 21 Texas NICRs; the percentage of SCD use billed as intensive ranged from 4% to 50% across Texas NICRs (varying 12.5-fold; Fig 1). The CV for rate of overall SCDs per 100 infants was 44; CVs were higher for intensive and intermediate days (Table 3). The mean LOS across NICRs was 2.33 days (range: 1.83–2.76); the mean LOS for children with a SCD was 4.75 days (range: 3.01–7.95). Texas 30-day readmission rates ranged across NICRs from 1.31% to 4.39% in Texas (mean: 2.33%; Table 2).

Across both states, there was no association between the number of intensive and intermediate SCDs, suggesting an absence of substitution of one level of care for another (Pearson’s r: −0.09; P = .64). We did not identify a regional association between the LOS or number of SCDs among infants with a SCD and 30-day all-hospital readmission risk for the general cohort in either state (Supplemental Table 7).

For all conditions, moderate to high variation was noted across measures of SCDs (total, intermediate, and intensive) and payers (Table 4). Overall SCD use was highest for infants with tachypnea (TX) and hypoglycemia (MA); variation in SCD use was greatest for NAS (TX) and sepsis (MA).

TABLE 4

Rates of Diagnosis, SCD Use, 30-Day Readmission, and LOS for Infants by Diagnosis Across States and NICRs

Diagnosis and Region and/or PayerDiagnostic Rate, Rate per 100 Infants (CV)SCD Use (CV)LOS, Average, d (CV)30-d Readmission, % (CV)
Rate of SCDs per 100 InfantsRate of Intermediate SCDs per 100 InfantsRate of Intensive SCDs per 100 InfantsAverage No. SCDs Among Infants With SCDs
NAS        
 Massachusetts 0.80 (68) 57.13 (27) 48.02 (39) 9.11 (60) 13.28 (25) 10.59 (22) 14.27 (41) 
  Medicaid 2.14 (44) 58.10 (24) 48.66 (36) 9.43 (61) 13.18 (28) 10.80 (22) 15.94 (48) 
  Commercial 0.23(35) 53.50 (34) 45.57 (45) 7.91 (99) 13.71 (24) 9.82 (24) 7.91 (86) 
 Texas 0.03 (141) 69.57 (57)a 34.78 (109)a 34.78 (137)a 20.44 (55) 16.22 (72) 0.00 
Hyperbilirubinemia        
 Massachusetts 26.37 (19) 8.62 (18) 6.64 (27) 1.98 (47) 5.71 (17) 2.96 (7) 2.46 (21) 
  Medicaid 22.07 (26) 10.30 (27) 7.97 (37) 2.33 (40) 5.93 (20) 2.71 (13) 4.12 (38) 
  Commercial 28.18 (22) 8.06 (26) 6.20 (31) 1.86 (53) 5.62 (13) 3.05 (6) 1.91 (29) 
 Texas 18.08 (49) 18.51 (57) 14.08 (57) 4.42 (112) 4.75 (29) 3.04 (26) 3.15 (59) 
Tachypnea        
 Massachusetts 2.83 (28) 50.01 (19) 36.61 (38) 13.4 (66) 4.89 (14) 4.00 (13) 3.74 (33) 
  Medicaid 2.64 (28) 51.65 (26) 36.24 (45) 15.41 (77) 4.92 (20) 3.94 (22) 7.71 (56) 
  Commercial 2.91 (31) 49.38 (15) 36.75 (37) 12.63 (68) 4.87 (12) 4.02 (9) 2.22 (108) 
 Texas 3.54 (63) 71.17 (18) 47.54 (52) 23.62 (78) 4.73 (19) 4.51 (22) 2.67 (98) 
Hypoglycemia        
 Massachusetts 1.45 (40) 57.84 (22) 44.76 (31) 13.08 (48) 5.58 (29) 4.55 (24) 4.14 (38) 
  Medicaid 1.31 (34) 56.40 (31) 43.01 (42) 13.34 (54) 5.65 (45) 4.45 (38) 8.31 (93) 
  Commercial 1.50 (51) 58.36 (39) 45.39 (39) 12.98 (70) 5.55 (13) 4.59 (14) 2.61 (64) 
 Texas 1.45 (59) 57.56 (42) 41.93 (80) 15.63 (106) 5.21 (38) 4.29 (35) 2.80 (137) 
Hypothermia        
 Massachusetts 1.63 (37) 36.72 (31) 30.63 (37) 6.08 (83) 5.6 (16) 4.09 (10) 13.63 (41) 
  Medicaid 1.65 (53) 39.78 (33) 34.05 (39) 5.73 (104) 5.00 (50) 3.63 (27) 20.75 (41) 
  Commercial 1.62 (37) 35.40 (35) 29.16 (40) 6.23 (86) 5.89 (20) 4.29 (8) 10.56 (44) 
 Texas 0.88 (89) 38.57 (71) 35.15 (72) 3.41 (197) 5.00 (29) 3.7 (34) 2.56 (188) 
Evaluation for sepsis        
 Massachusetts 6.37 (42) 33.47 (37) 25.85 (46) 7.62 (68) 5.16 (19) 3.62 (17) 3.66 (45) 
  Medicaid 4.61 (45) 37.78 (41) 27.96 (52) 9.82 (62) 4.90 (33) 3.36 (26) 7.26 (57) 
  Commercial 6.71 (41) 30.89 (37) 24.29 (45) 6.59 (70) 5.22 (12) 3.65 (16) 2.55 (71) 
 Texas 7.93 (36) 44.10 (42) 31.80 (60) 12.30 (91) 4.74 (21) 3.56 (27) 2.66 (60) 
Diagnosis and Region and/or PayerDiagnostic Rate, Rate per 100 Infants (CV)SCD Use (CV)LOS, Average, d (CV)30-d Readmission, % (CV)
Rate of SCDs per 100 InfantsRate of Intermediate SCDs per 100 InfantsRate of Intensive SCDs per 100 InfantsAverage No. SCDs Among Infants With SCDs
NAS        
 Massachusetts 0.80 (68) 57.13 (27) 48.02 (39) 9.11 (60) 13.28 (25) 10.59 (22) 14.27 (41) 
  Medicaid 2.14 (44) 58.10 (24) 48.66 (36) 9.43 (61) 13.18 (28) 10.80 (22) 15.94 (48) 
  Commercial 0.23(35) 53.50 (34) 45.57 (45) 7.91 (99) 13.71 (24) 9.82 (24) 7.91 (86) 
 Texas 0.03 (141) 69.57 (57)a 34.78 (109)a 34.78 (137)a 20.44 (55) 16.22 (72) 0.00 
Hyperbilirubinemia        
 Massachusetts 26.37 (19) 8.62 (18) 6.64 (27) 1.98 (47) 5.71 (17) 2.96 (7) 2.46 (21) 
  Medicaid 22.07 (26) 10.30 (27) 7.97 (37) 2.33 (40) 5.93 (20) 2.71 (13) 4.12 (38) 
  Commercial 28.18 (22) 8.06 (26) 6.20 (31) 1.86 (53) 5.62 (13) 3.05 (6) 1.91 (29) 
 Texas 18.08 (49) 18.51 (57) 14.08 (57) 4.42 (112) 4.75 (29) 3.04 (26) 3.15 (59) 
Tachypnea        
 Massachusetts 2.83 (28) 50.01 (19) 36.61 (38) 13.4 (66) 4.89 (14) 4.00 (13) 3.74 (33) 
  Medicaid 2.64 (28) 51.65 (26) 36.24 (45) 15.41 (77) 4.92 (20) 3.94 (22) 7.71 (56) 
  Commercial 2.91 (31) 49.38 (15) 36.75 (37) 12.63 (68) 4.87 (12) 4.02 (9) 2.22 (108) 
 Texas 3.54 (63) 71.17 (18) 47.54 (52) 23.62 (78) 4.73 (19) 4.51 (22) 2.67 (98) 
Hypoglycemia        
 Massachusetts 1.45 (40) 57.84 (22) 44.76 (31) 13.08 (48) 5.58 (29) 4.55 (24) 4.14 (38) 
  Medicaid 1.31 (34) 56.40 (31) 43.01 (42) 13.34 (54) 5.65 (45) 4.45 (38) 8.31 (93) 
  Commercial 1.50 (51) 58.36 (39) 45.39 (39) 12.98 (70) 5.55 (13) 4.59 (14) 2.61 (64) 
 Texas 1.45 (59) 57.56 (42) 41.93 (80) 15.63 (106) 5.21 (38) 4.29 (35) 2.80 (137) 
Hypothermia        
 Massachusetts 1.63 (37) 36.72 (31) 30.63 (37) 6.08 (83) 5.6 (16) 4.09 (10) 13.63 (41) 
  Medicaid 1.65 (53) 39.78 (33) 34.05 (39) 5.73 (104) 5.00 (50) 3.63 (27) 20.75 (41) 
  Commercial 1.62 (37) 35.40 (35) 29.16 (40) 6.23 (86) 5.89 (20) 4.29 (8) 10.56 (44) 
 Texas 0.88 (89) 38.57 (71) 35.15 (72) 3.41 (197) 5.00 (29) 3.7 (34) 2.56 (188) 
Evaluation for sepsis        
 Massachusetts 6.37 (42) 33.47 (37) 25.85 (46) 7.62 (68) 5.16 (19) 3.62 (17) 3.66 (45) 
  Medicaid 4.61 (45) 37.78 (41) 27.96 (52) 9.82 (62) 4.90 (33) 3.36 (26) 7.26 (57) 
  Commercial 6.71 (41) 30.89 (37) 24.29 (45) 6.59 (70) 5.22 (12) 3.65 (16) 2.55 (71) 
 Texas 7.93 (36) 44.10 (42) 31.80 (60) 12.30 (91) 4.74 (21) 3.56 (27) 2.66 (60) 

The CV is the SD divided by the mean multiplied by 100.

a

Analysis includes only NICRs where infants had a diagnosis of NAS.

b

Includes only NICRs where infants had SCDs.

Compared with the Massachusetts commercially insured cohort, the rate and magnitude of SCD variation was greater in Texas across all conditions except hypoglycemia. Between-state differences in SCD use by condition were most notable for jaundice, with rates in Texas more than twice those observed among the Massachusetts commercially insured. Among infants with any SCDs, the average number of SCDs was lower in Texas than in the Massachusetts commercial cohort for all diagnoses but NAS. SCD use was greater among the Massachusetts Medicaid cohort than the Massachusetts commercially insured cohort for all conditions except hypoglycemia.

Excluding NAS because of its low incidence in Texas infants during the study period, a moderate association was observed between the number of NICR SCDs in all pairwise combinations of diagnostic subcohorts, with the exception of hypothermia (Supplemental Table 8). Weaker associations were noted for LOS. There was generally no observed association between inpatient NICR-level use and 30-day readmission rates (Supplemental Table 7). Neither lower duration of care (LOS) nor lower rate of SCDs were associated with a higher readmission risk for any subgroup.

In this population-based cohort study of low-risk infants born at ≥35 weeks GA, we identified marked regional variation in use of NICU care in Massachusetts and Texas. These findings are added to a growing body of literature suggesting a lack of standardization in care intensity for near-term infants.8,10,11  We did not find a correlation between regional SCD use and 30-day readmission risk, suggesting there may not be a short-term benefit to higher intensity of care for some infants. In our study, we also report novel descriptions of variation in care for individual diagnoses and association of readmissions with care patterns.

Across all NICRs, SCD use ranged from 3.82 to 22.58 days per 100 low-risk infants. In a cross-sectional study, using the National Center for Health Statistics Natality File, Harrison et al10  also identified nearly sixfold variation in NICU admission rates for normal and above-normal BW newborns. For overall SCD use, we found CVs to range from 27 to 44 across payer- and state-specific cohorts. In a 2019 study, Goodman et al,11  assessing Medicaid-insured, late-preterm infants in Texas found a CV of 19 for SCD use across NICRs, also indicating moderate to high variation. Interhospital variation has been found to exceed regional variation. In the same study of Medicaid-insured Texas infants, investigators found a crude CV of 27 for late-preterm SCDs across 100 of the state’s largest hospitals. Schulman et al8  found NICU admission rates ranging from 1.1% to 37.7% among inborn infants ≥34 weeks’ GA across 130 California hospitals. Notably, both Goodman et al11  and Schulman8  concluded that variation was not explained by measured differences in health risk at birth. Edwards and Horbar7  found that only 15% of infants ≥34 weeks’ GA admitted to Vermont Oxford Network NICUs could be classified as high acuity, but this ranged from 0% to 100% across sites. Ziegler et al12  found that, across 19 US hospitals, NICU admissions without absolute or relative identified cause among infants 35 to 42 weeks’ GA ranged from 0% to 59.4%. Hospital site of care was found to be the most important variable associated with this variation.

This consistent identification of marked variation in care patterns for near-term infants, not apparently driven by acuity of illness, warrants further investigation. Although levels of neonatal care ranging from level 1 (well-newborn nursery) to level 4 (regional NICU) have been defined by the American Academy of Pediatrics,30  there are differences in the criteria physicians and hospitals use to admit newborns to NICUs.8,12,33  These differences appear to increase with decreasing acuity, as evidenced by greater variation in care among near-term infants than premature infants.10,11  Drivers of this variation are not well studied. Patient-level factors outside of illness acuity are one possible source of variation. In our study, we assessed variation by newborn-level payer type and found high variation across all payer groups. Although the intensity of SCD use was greater among Massachusetts Medicaid patients than Massachusetts commercially insured, the highest use was observed in the Texas commercial cohort. The high regional association of SCDs between payers in Massachusetts is further indication of drivers outside of payer type. In our study, we were unable to assess use by race and ethnicity or other demographics; further investigation into the relationship between these variables and newborn care patterns is warranted.

In previous studies, researchers have also proposed system-level drivers of newborn care variation. In the absence of specific guidance surrounding care levels for near-term infants, hospitals often develop their own standards on the basis of GA, weight, or other characteristics.8,12  Although these guidelines may be used to streamline care, they are not typically grounded in strong evidence, and little is known about outcomes related to these practices. NICU bed availability may impact center-specific care guidelines. Several studies have revealed that more NICU bed availability is associated with higher NICU use,10,34,35  and this is also a well-known driver of inpatient use in adults.31  Deregionalization efforts intended to improve NICU access for preterm infants have led to rapid NICU growth; financial incentives to support continued success of centers may drive care patterns in some circumstances.9  Conversely, lack of local availability of NICU beds or neonatologists and a subsequent need to transfer for higher level care may increase NICU admission thresholds.

Our finding of variation in NICU use across a subset of conditions in near-term infants is novel. Diagnostic rates were relatively similar between Texas and Massachusetts, with the exception of NAS; in both the overall Massachusetts cohort and the commercially insured Massachusetts cohort, NAS was diagnosed much more frequently than in Texas. These findings are consistent with known incidence of NAS, which is relatively low in Texas in comparison with other states and is also more prevalent among Medicaid-insured infants.36  Although acuity levels vary among infants with the same diagnosis, high variation observed across use measures for all conditions suggests a need for further efforts to identify effective and efficient care patterns to support evidence-based, condition-specific guidelines. The 3 existing national guidelines for the 6 conditions assessed in this study do not address site, level, or length of routine care.27,37,38 

Comparisons between the Texas and Massachusetts commercial cohorts revealed higher SCD use in Texas for all conditions but hypoglycemia. This discrepancy was most notable for jaundice, which was diagnosed in 18% of Texas infants and 26% of Massachusetts infants, suggesting that care standardization for this population could have a substantial impact. Texas children with at least 1 SCD had fewer SCDs than the Massachusetts commercially insured across all conditions but NAS; this may suggest a lower threshold for higher level of care delivery in Texas. The moderate correlation found between pairwise conditions across NICRs suggests a general regional approach to care that may impact newborns across conditions.

Further investigation into newborn care patterns requires measurement of postdischarge outcomes to identify practices that appear to be more efficient without adverse consequences. In secondary analyses, we did not observe that a lower average regional number of SCDs or LOS was associated with more 30-day readmissions. Similarly, in a 2020 study evaluating outcomes related to level of care among a high GA and BW cohort, Braun et al14  found no changes in readmissions or mortality as NICU use decreased. Expanding measurement of postdischarge outcomes to include those such as emergency department visits, weight, feeding patterns, and outpatient care use is an important direction for further studies.

This study has some limitations. First, the accuracy of claims data relies on coding practices used by individual providers and facilities, which may vary. Claims data do not provide detailed clinical information. We were limited to the use of ICD-9 codes to identify our low-risk cohort; this strategy may have included some higher acuity newborns and, conversely, excluded some low-risk newborns. The selection of exclusion codes, although performed in a rigorous way with multidisciplinary input, is somewhat subjective because diagnoses that truly require NICU admission remain controversial. In our study, we evaluated 2 states with different demographic characteristics, and we were limited to commercial data in Texas, which represents a minority of patients born in Texas over the study period. Comparisons across states should be made cautiously, particularly in light of our inability to account for demographics outside of payer type and other state-specific policies and characteristics. Finally, trends observed during our study period may not reflect the most up to date care patterns. However, to our knowledge, care standards for this newborn population have remained relatively stable over the elapsed time period, with the exception of NAS, in which stronger evidence has developed to support care outside the NICU setting.24,39,40 

Wide variation exists in SCD use across NICRs in Texas and Massachusetts among this low-risk neonatal cohort, both in aggregate and within specific conditions and payer cohorts. In this population, higher intensity of care at a regional level did not correlate with 30-day readmission rates. Primary drivers of this variation remain inadequately studied. Given the increase in NICU use among this population over time and potential costs and harms associated with NICU care, more research is needed to support care evidence-based condition-specific guidelines.

Drs House and Goodman conceptualized and designed the study, designed the data collection strategy, analyzed data, and drafted the initial manuscript; Dr Singh conceptualized and designed the study and reviewed data analysis; Mr Wasserman conceptualized and designed the study and conducted data collection and analysis; Dr Ganduglia-Cazaban and Ms Kim designed data collection tools and conducted data collection and analysis; and all authors reviewed and revised the manuscript and approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

FUNDING: Supported by the Charles H. Hood Foundation and The Kettering Family Foundation. The funder did not participate in the work.

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Competing Interests

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.

FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.

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