Transfer Patterns of Very Low Birth Weight Infants for Convalescent Care

We used data submitted by VON members in the United States from January 1, 2006, to December 31, 2020, for infants with a birth weight of 401 to 1500 g or 22 to 29 weeks’ gestation who were born in the member hospital or admitted within 28 days of birth without first having gone home. Member NICUs contribute data from medical records using uniform definitions.⁷  All data undergo automated checks for quality and completeness at the time of submission. The University of Vermont’s committee for human research determined that use of VON’s de-identified research repository for this analysis was not human subjects research.

VON collects data on initial disposition (home, transferred, died, still hospitalized as of first birthday), posttransfer disposition for transferred infants (home, transferred again, died, readmitted, still hospitalized as of first birthday), disposition after readmission for readmitted infants (home, transferred, died, still hospitalized as of first birthday), and ultimate disposition (home, died, still hospitalized as of first birthday). Reason for transfer is collected for only the initial disposition (extracorporeal membrane oxygenation, growth/discharge planning, medical/diagnostic services, surgery, chronic care, or other). Initial and subsequent LOS for transferred infants are also collected. For outborn infants, day of life at admission to the VON center is recorded. Infants who transfer between VON member NICUs are counted at the earlier NICU.

NICU types for VON members are collected through the VON annual membership survey: Type A—restriction on assisted ventilation or no surgery, Type B—major surgery, and Type C—cardiac surgery requiring bypass. For outborn infants, birth hospital name was collected in 2015, and American Academy of Pediatrics NICU level of birthplace was determined from publicly available hospital data. American Hospital Association data were used to examine hospital ownership (government-owned, nonprofit, investor-owned). NICU census regions and divisions were classified according to the U.S. Census Bureau classifications as: West (Mountain and Pacific), Midwest (East North Central and West North Central), South (South Atlantic, East South Central, and West South Central), and Northeast (New England and Mid-Atlantic).⁸ 

We examined delivery room (DR) (tracheal intubation) and NICU (conventional ventilation, high-frequency ventilation, postnatal steroids, nasal continuous positive airway pressure, inhaled nitic oxide) usage measures and measures at discharge or transfer (oxygen, monitor, enteral feeding). These measures were only recorded while the infants were at VON centers. For infants transferred for convalescence, updated measures at discharge were only recorded for readmitted infants.

Examined outcome variables have been previously defined⁹  and included respiratory distress syndrome, focal intestinal perforation/necrotizing enterocolitis (NEC), early-onset sepsis (≤day 3 of life), late-onset sepsis (>day 3 of life), severe intraventricular hemorrhage, severe retinopathy of prematurity (ROP), chronic lung disease, and pneumothorax. We also examined survival to discharge without a major morbidity (defined as ≥1 of: NEC/focal intestinal perforation, early-onset sepsis, late-onset sepsis, severe intraventricular hemorrhage, severe retinopathy of prematurity, chronic lung disease, pneumothorax, or cystic periventricular leukomalacia) and anthropometric variables (weight, head circumference, growth velocity) at disposition. Reporting hospitals tracked mortality and total LOS before hospital discharge and after transfer until ultimate disposition. Morbidities and anthropometric variables were only tracked until discharge from the VON hospital. For infants transferred for convalescence, updated morbidities and weight were only recorded for readmitted infants.

We identified 4 groups of infants among NICU survivors:

1. infants who were discharged from the hospital as their initial disposition;

2. infants who were transferred for their initial disposition with the reason for transfer being growth/discharge planning, labeled as TFC, and were then discharged from the hospital; and

3. infants who failed TFC; that is, they were transferred for growth/discharge planning but then were either (a) readmitted to the original center they transferred from for the growth/discharge planning, or (b) transferred again to a different center.

We conducted descriptive analyses, examining among the 4 groups of infants the distribution of: (1) hospital, newborn, and maternal characteristics, and (2) DR and NICU usage measures and outcomes. We also examined the percentage of infants who transferred for convalescence from type C NICUs by region. We used logistic regression models with birth year modeled as a linear effect to examine whether changes over time in rates of TFC and failed TFC were significant. To examine the risk factors associated with failed TFC, we used modified Poisson regression models with robust variance estimation. The examined variables in the model included gestational age, birth weight z-score, outborn status, race/ethnicity, sex, presence of major congenital anomalies,⁷  DR intubation, respiratory distress syndrome, initial LOS, and weight z-score at transfer.

A total of 591 559 neonates were inborn at 836 VON centers and 77 204 neonates were outborn and transferred to 768 VON centers. Among the inborn infants, 27 051 (4.6%) died in the DR, resulting in 641 712 infants who were either born at or transferred to a VON NICU. A total of 28 985 (4.5%) infants transferred for growth/discharge planning. Data on the second disposition for infants transferred for growth/discharge planning were available for 28 186 infants, among whom 2551 (9.1%) failed the TFC, 1771 (6.3%) were readmitted, and 780 (2.8%) were transferred again (Fig 1). Moreover, 182 (0.65%) infants transferred for convalescence died before hospital discharge.

Table 1 shows hospital, newborn, and maternal characteristics by disposition status. Across regions, New England (18.8%) had the highest whereas East South Central (2.2%) had the lowest percentage of TFC. Compared with infants discharged from the hospital, infants transferred for convalescence were more than twice as likely to be outborn (26.9% vs 10.9%) and to be born at level C NICUs (48.2% vs 25.8%). More than 50% of infants transferred for convalescence were transferred to type A NICUs, but 15.5% were also transferred to hospitals without NICUs. Compared with infants discharged from the hospital, infants transferred for convalescence were less likely to be born at investor-owned hospitals (4.3% vs 9.1%) and more likely to be born at nonprofit hospitals (83.2% vs 76.2%).

Compared with infants transferred for convalescence and discharged from the hospital, infants who failed TFC were more likely to be outborn, transfer to a hospital without a NICU, have a lower gestational age, and have a major congenital anomaly (Table 1). In a regression model, major congenital anomalies increased the risk of failed TFC by 2.51-fold (95% confidence interval 2.08–3.03) (Fig 2). Other factors associated with failed TFC included gestational age, birth weight z-score, outborn status, race, sex, DR intubation, respiratory distress syndrome, and weight z-score at transfer time.

Infants who were discharged from the hospital had a similar clinical course to infants who were transferred for convalescence and then discharged from the hospital. For infants transferred for convalescence who were subsequently discharged from the hospital, oxygen (29.7%), monitor (84.2%), and any human milk (64.4%) were measured at the initial disposition; that is, at transfer but were measured at discharge to home for infants who were not transferred for convalescence (oxygen: 13.7%, monitor: 21.9%, any human milk: 49.1%) (Table 2). Infants who failed TFC had higher rates of DR intubation, conventional and high-frequency ventilation, postnatal steroids, and inhaled nitric oxide compared with infants who were transferred for convalescence and discharged from the hospital. For infants transferred for convalescence who were readmitted, oxygen (42.8%), monitor (71.0%), and any human milk (52.5%) were measured at the subsequent disposition after readmission.

Infants who transferred for convalescence and were then discharged from the hospital had similar outcomes to infants who were discharged from the hospital without being transferred (Table 3). However, infants who transferred for convalescence and were in the VON hospital at the recommended age for a retinal exam were less likely to receive a retinopathy of prematurity exam (82.0% vs 94.5%) than infants who were not transferred for convalescence. The median postmenstrual age and the mean weight at initial disposition were 3.7 weeks and 793 g, respectively, lower for infants who transferred for convalescence and were subsequently discharged from the hospital than those who were discharged from the hospital at their initial disposition. At discharge home, the median postmenstrual age (37.6 weeks) was similar for both groups.

Infants who failed TFC and were transferred again had a higher rate of all the examined morbidities than infants who transferred for convalescence and were then discharged from the hospital (Table 3). Among infants who transferred for convalescence and were then discharged from the hospital, rates of any major surgery and survival to discharge without morbidities were 11.6% and 72.9%, whereas they were 26.2% and 54.3%, respectively, among infants who transferred for convalescence and transferred again. Among infants who transferred for convalescence and were readmitted, rates of any major surgery and survival to discharge without morbidities were 49.0% and 36.6%, respectively; the higher-outcome rates reported in this group might be partially because of the longer reporting period given their readmission.

The median total LOS (59 days) was the same if infants were discharged from the hospital or if they transferred for convalescence and were then discharged from the hospital (Fig 3). However, the LOS was much higher if infants failed the TFC.

We observed major regional variation in TFC from type C NICUs (Table 4). In the South Atlantic region among 26 type C NICUs, the percentage of TFC ranged between 0% and 84%. West South Central had the lowest variation; the percentage of TFC ranged between 0% and 13%. In 7 regions, there were type C NICUs that did not TFC any infants.

The rate of TFC decreased significantly from 9.8% in 2006% to 3.9% in 2020 (P <.001) (Table 5). However, there was no significant trend over time in the overall rate of failed TFC (P = .28). The rate of TFC decreased over time across all regions (Supplemental Fig 4).

In a study of >665 000 VLBW infants, we show that the overall rate of TFC was low at 4.5% and decreased by 60% over time. New England (18.8%) had the highest whereas East South Central (2.2%) had the lowest percentage of TFC from type C NICUs. We also show that the rate of failed TFC was 9.1%; 6.3% of infants were readmitted and 2.8% were transferred again. Having a major congenital anomaly was the strongest risk factor for a failed TFC. Among the infants transferred for convalescence, <1% died before hospital discharge.

From a regionalized systems perspective, the practice of TFC is necessary because it promotes the intent of achieving risk-appropriate care in a resource-efficient manner when intensive care is no longer required.¹  However, the major regional differences and the decrease over time in TFC bring into question the potential contributors driving this variation. Potential contributors include state and financial policies. A review of state policies supporting neonatal transfer showed that only 16 of the 34 states (47%) with a transfer policy noted a TFC component, whereas 25 of the 31 states (81%) with a transfer reimbursement policy did not specifically address TFC reimbursement.¹⁰  However, even within regions, we observed enormous variation in TFC among tertiary NICUs. Potential contributors to NICU variation in the TFC practice include high NICU census and competition between hospitals. High NICU census has been previously associated with increased likelihood of discharging moderately preterm infants¹¹  and might also contribute to the TFC of VLBW infants as suggested by parents’ perception of the reason for TFC of their VLBW infants.¹²  On the opposite end, a hospital receiving reimbursement for care of an infant, has no incentive to TFC the infant because another institution would receive the convalescing care reimbursement.^13,14  We are not sure how hospital ownership might affect the TFC practice, but we found that infants who transferred for convalescence were less likely to be born at investor-owned hospitals and more likely to be born at nonprofit hospitals than infants who were discharged from the hospital.

Beyond state- and NICU-level contributors to TFC, sociodemographic factors, parental preferences, and geography might also play a role. Two previous studies have shown that TFC was associated with having private insurance coverage,^15,16  which might indicate that this elective nature of transfer might be more likely covered by private insurers.¹⁵  However, this has not been replicated in another study.⁵  We are unsure if parental preferences might impact TFC or if that is a decision solely made by the NICU personnel or the insurance provider. A study based on 236 families showed that <50% of families wanted the TFC, citing their trust with the medical team at the high-level NICU.¹²  Geographic proximity of the patient’s home to community hospitals with sufficient facilities¹⁵  and nursing staff appropriately trained to care for these high-risk infants is another important contributor to TFC.

The overall rate of failed TFC was 9.1%. However, the rate of failed transfer was 15.4% if infants were transferred to hospitals without a NICU and 7.7% if infants were transferred to hospitals with level II NICUs. In a study of 148 VLBW infants who transferred to community hospitals with mostly level II nurseries, 19% were readmitted to an intensive care setting before discharge from the hospital with feeding intolerance, severe apnea, respiratory distress, infection, or ROP surgery being the main causes for readmission.⁵  In another study of 2178 infants born <37 weeks’ gestation, 13% of infants failed TFC, with the most common reason for transfer to a level IV NICU being admission for specialized radiology services, followed by apnea.¹⁷  We did not have data on the reasons for failed TFC. Additionally, we do not know why some infants transferred for convalescence were readmitted (6.3%) whereas others were transferred to different centers (2.8%) and whether these transferred infants also received high-acuity care. Thus, the overall TFC failure rate might be somewhere between 6.3% and 9.1%.

Although failure in TFC might be expected in certain cases given this high-risk group, failure might also signal the nonreadiness of these infants to transfer or the poor communication between the transferring and the receiving hospital about the medical needs of the infant and the capabilities of the receiving hospital.^5,18  Some risk factors for infants who failed TFC included having a major congenital anomaly, being outborn, having a lower gestational age, and having respiratory distress syndrome.

Infants who transferred for convalescence and were discharged from the hospital were less likely to receive retinal exams at the recommended age (82.0%) compared with infants who were discharged from the hospital (94.5%). We did not have data on whether these infants who transferred for convalescence and were subsequently discharged from the hospital received retinal examination at the center they transferred to. In a previous study, infants transferred for convalescence were twice (risk ratio = 2.16; 95% confidence interval: 1.05–4.44) as likely to not receive ROP follow-up care compared with infants who were not transferred for convalescence.¹⁹  Similarly, another study of 401 to 1000-g infants showed that infants transferred for convalescence were less compliant with a neurodevelopmental assessment at 18 to 22 months’ corrected age.¹⁶  This emphasizes the importance of communication between the transferring and the receiving hospital to ensure adequate follow-up care needs are delivered to these high-risk infants.

Studies examining duration of hospitalization among VLBW or extremely low birth weight infants transferred to the community hospital compared with infants discharged from the hospital from the regional center have either reported a similar,¹⁸  a trend toward a longer,⁵  or a shorter LOS.^16,20  In our study, the median total LOS (59 days) was the same for infants who were discharged from the hospital and infants who were transferred for convalescence and then discharged from the hospital. However, the median total LOS was longer by >1 month for infants who failed the TFC.

Strengths of our study include a large sample size of VLBW infants, allowing us to examine on a national level regional TFC practices. We also had data on initial and subsequent LOS among transferred infants until they were discharged from the hospital. Limitations include lack of data on the reasons for the regional variation in the TFC rates. Additionally, most of our measures were from the initial LOS at the VON center; we only had updated measures for infants who were transferred for convalescence and readmitted. We also did not have data on the cost-effectiveness of TFC, the longer-term outcomes such as readmission rates and emergency department utilization, and the reasons for the failed TFC. We used the term “convalescent care” for the care received by infants after transfer, but recognize that this may be an oversimplification for the continuing care and discharge planning that may be required by these high-risk infants.

In this VLBW cohort, the overall rates of TFC, TFC failure, and death among infants transferred for convalescence were low. Infants who were transferred for convalescence and discharged from the hospital had an LOS similar to infants who were not transferred for convalescence. Future studies should weigh the cost-effectiveness, risks, and benefits of TFC that might differ on the basis of geography and the capabilities of surrounding community hospitals that would accept these high-risk infants for continuing care.

We thank our colleagues who submit data to Vermont Oxford Network on behalf of infants and their families. Participating centers are listed in Supplemental Table 6.

DR

delivery room

LOS

length of stay

NEC

necrotizing enterocolitis

ROP

retinopathy of prematurity

TFC

transfer for convalescence

VLBW

very low birth weight

VON

Vermont Oxford Network