Published online October 31, 2008
PEDIATRICS Vol. 122 No. 5 November 2008, pp. e1048-e1052 (doi:10.1542/peds.2008-0412)
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ARTICLE

Mortality and Morbidity by Month of Birth of Neonates Admitted to an Academic Neonatal Intensive Care Unit

Thomas D. Soltau, MDa, Waldemar A. Carlo, MDa, Jonathan Gee, MDb, Jeffrey Gould, MDc and Namasivayam Ambalavanan, MDa

a Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama
b Department of Internal Medicine and Pediatrics, Carolinas Medical Center, Charlotte, North Carolina
c Department of Pediatrics, Stanford University, Stanford, California


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
BACKGROUND. Clinical expertise and skill of pediatric housestaff improve over the academic year, and performance varies despite supervision by faculty neonatologists. It is possible that variation in clinical expertise of housestaff affects important clinical outcomes in infants in ICUs.

OBJECTIVE. Our goal was to test the hypothesis that there is a decrease in morbidity and mortality in infants admitted to an NICU over the course of the academic year.

DESIGN/METHODS. A retrospective analysis was conducted using data on infants with birthweight 401 to 1500 g and ≥24 weeks’ gestation (n = 3445) and infants with birth weights >1500 g (n = 7840) admitted to a regional NICU from January 1991 to June 2004. All infants were cared for by pediatric and neonatal housestaff supervised by neonatologists. Analysis of mortality and morbidity (intraventricular hemorrhage grades 3–4/periventricular leukomalacia, necrotizing enterocolitis ≥ Bell stage 2, and bronchopulmonary dysplasia) over time were performed by repeated measures analysis of variance and the {chi}2 test.

RESULTS. Mortality rate in the 401 to 1500 g cohort, as well as the >1500 g cohort did not decrease over time during the academic year and was similar between the first (July–December) and second (January–June) halves of the academic year. There were no differences noted over the academic year for any of the morbidities.

CONCLUSIONS. Morbidity and mortality in infants admitted to an academic NICU did not change significantly over the academic year. These observations suggest that the quality of care of critically ill neonates is not decreased early in the academic year.

Key Words: infant • premature • July phenomenon

Abbreviations: BPD—bronchopulmonary dysplasia • NEC—necrotizing enterocolitis • IVH—intraventricular hemorrhage • PVL—periventricular leukomalacia • CI—confidence interval

Prematurity continues to be a major cause of infant mortality and subsequent physical and neurodevelopmental disabilities despite recent advances in neonatal care.1–3 Premature infants are at high risk for morbidity and mortality because of bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and periventricular leukomalacia (PVL). Term and late preterm infants admitted to NICUs are also at increased risk for morbidity and mortality.4 We sought to determine whether experience of the housestaff that provides medical care for these infants is associated with mortality and major neonatal morbidities.

Efforts to characterize the variables that affect neonatal outcomes have focused primarily on patient characteristics such as birth weight, gender, race, gestational age, and markers of illness severity, such as ventilator requirements.1–6 The process of care delivery may affect morbidity and mortality as demonstrated in the adult critical care setting.7,8 Data on care processes have been used to improve cost and patient outcomes.7–9 Delivery of care in the NICU may depend on the level of skill and expertise of the caregiver.10 At the commencement of each academic year in July, academic medical centers have an influx of new trainee physicians who assume clinical responsibilities and other junior physicians receive increased clinical responsibilities leading to the concept of the "July phenomenon."11–17 The July phenomenon reflects the concern that the quality of care early in the academic year may be worse than later in the year as relatively inexperienced physicians garner more experience12 and the possibility that this difference in quality of care may lead to worse patient outcomes.

There is controversy in the literature whether such inexperience adversely impacts patient morbidity and mortality,11–17 and there are limited data on the potential impact on mortality and other important outcomes. This study was designed to test the hypothesis that major morbidities and mortality decrease over the academic year in admissions to a large academic NICU.


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Subject Selection
This study was a retrospective review of computerized records from the University of Alabama at Birmingham Regional NICU and was approved by the institutional review board. Records of all admissions from January 1991 until June 2004 were analyzed from the patient charts by a trained database specialist immediately after discharge of the infant. Infants with birth weight 401 to 1500 g and gestational age ≥24 weeks were analyzed for mortality and the common neonatal morbidities BPD, NEC, IVH, and PVL. Infants with >1500 g birth weight, who are at lower risk of morbidities, were analyzed only for mortality. In this time period, infants in this weight range were generally resuscitated unless they were <23 weeks’ gestation or parents requested no resuscitation if <25weeks’ gestation. Neonates who died in the delivery room (<1%) were not included. The University of Alabama at Birmingham NICU is a regional perinatal center for the state of Alabama with ~800 admissions per year of which approximately half are fetal referrals. Average daily census in the unit during the study period increased from 48 to 83, and ranged from 60 to 105 at the end of the study period. Approximately 30% of children received mechanical ventilation during their hospital stay. Between 110 and 175 infants with birth weight <1000 g were admitted per year. The NICU team is typically composed of 1 medical student, 4 pediatric interns (first-year residents), 3 pediatric second- or third-year residents, 1 neonatal fellow, and 2 board-certified neonatal faculty members. Interns typically cared for 8 to 12 infants per day. Interns are usually on service in the NICU for a month in the first half of the year (July to December) and again for another month in the second half of the year (January to June), whereas residents cover 1 month per year. An intern is on call with an upper-level (second- or third-year) resident at night. There is no preference for a more experienced upper-level resident or fellow to be on service in the first half of the academic year, and new fellows and residents are on service in July. All infants were initially cared for by pediatric residents and neonatology fellows, with supervision by faculty neonatologists. Two faculty neonatologists provided general supervision with daily rounds and telephone counsel and physical assistance as needed for emergencies and anticipated delivery room resuscitation. Fellows in training were initially available at night as needed, but have had a 24-hour presence from 1997 onward. Additional assistance primarily for critically ill neonates and resuscitations was provided by an "in-house" faculty physician every night from 2001 onward. Patient rounds with faculty neonatologists are twice daily on critically ill infants and once daily in neonates in less ill infants (level 2). Residents and interns are given considerable freedom and latitude in clinical decision-making and management. Three neonatal nurse practitioners and a hospitalist (a pediatric board-certified physician) were added during the study period. The role of these caregivers is to provide care for more stable infants who are not on mechanical ventilation or continuous positive airway pressure. It is unlikely that addition of these caregivers impacted the results of our study, because residents cared for infants during the period of maximal risk for death, IVH, and other major morbidities, except perhaps for some infants with late onset of NEC.

Data Analysis
For purposes of analysis, data were grouped by month of birth or admission across the years examined. The academic year was defined as beginning on July 1 and lasting until June 30 of the next year. Mortality was defined as death of a neonate before initial discharge from the hospital regardless of cause or preexisting comorbidities. Morbidity was defined as BPD (oxygen requirement at 28 days), NEC ≥ stage 2 (modified Bell stage),18,19 and severe IVH grades 3 to 4 (Papile classification)20 or cystic PVL. Mortality and morbidity rates over time were analyzed by repeated measures analysis of variance. Comparisons were made between the first half of the academic year (July through December) and the second half of the academic year (January through June) by the {chi}2 test. A P value of ≤.1 was considered significant in this study.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Between January 1991 and June 2004, 3445 infants with birth weight 401 to 1500 g and >24 weeks’ gestational age and 7840 infants with birth weight >1500 g were admitted. The population admitted to the NICU was 47% white, 46% black, 4% Hispanic, and 3% of other racial backgrounds. A total of 52% were male, and ~70% were either uninsured or Medicaid recipients. Approximately 80% of these infants were inborn.

Mortality rates for infants who weighed 401 to 1500 g did not significantly differ by month across the academic year (Fig 1). In addition, mortality rate did not differ when compared between the first half of the year and the second half. The rates of the BPD, IVH 3-4/PVL, and NEC did not differ significantly over time (all P >.2, Figs 2–4). The month of July had the fourth-lowest mortality rate, the third-lowest rate of BPD, and the third-lowest rate of IVH 3-4/PVL. Mortality rates did not change significantly across the academic year for the infants with birth weight >1500 g (data not shown).


Figure 1
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  		FIGURE 1 All cause mortality in infants between 401 and 1500g by month of birth demonstrating no significant differences in mortality rate across the academic year (mean, 95% confidence interval [CI], P = .49, by repeated measures analysis of variance).

 

Figure 2
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  		FIGURE 2 BPD (defined as oxygen requirement at 28 days of age) in infants between 401 and 1500 g by month of birth demonstrating no significant difference in BPD rate across the academic year (mean, 95% CI, P = .98, by repeated measures analysis of variance).

 

Figure 4
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  		FIGURE 4 NEC (at least stage II) in infants between 401 and 1500 g by month of birth demonstrating no differences in NEC occurrence across the academic year (mean, 95% CI, P = .63, by repeated measures analysis of variance).

 

   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
We undertook our study to examine whether the level of housestaff expertise influences outcomes in neonatal care. We based our hypothesis on the concept that there may be a "July phenomenon" in academic medical centers. Contrary to our hypothesis, our study demonstrated no significant difference in mortality or morbidity in the NICU over the course of the academic year. This is important as our study is the first to examine neonatal mortality or major morbidities instead of care delivery processes.

Possible confounders within the study design result in some limitations to our study. Mortality and morbidity were evaluated based on month of birth and not on age of death or onset of morbidity. Thus, a patient may have been born in July, but died in September under the care of a neonatal team who were not involved in resuscitation at birth or in early care. However the level of housestaff experience is similar in the initial months of the academic year. In addition, if faculty physicians make the majority of decisions regarding patient care, the quality of care provided by residents may not sufficiently impact neonatal outcomes. In our institution, fellows and residents have considerable autonomy, both at the time of admission and during daily care and ventilator changes, although the faculty neonatologist supervises and provides the overall treatment plan. This is probably similar to many other academic institutions, and hence our results may be extrapolatable to institutions with similar processes of care. In general, there has been a trend toward increasing fellow and faculty supervision in recent years. However, we did not find a significant difference in mortality or morbidity between the early years (1991–94) and recent years (2001–4). The recent introduction of the 80-hour resident work hour rules may affect the training and skill level of pediatric residents, and impact the generalizability of our study for the future. The rates of morbidity may seem high partly because our center is the regional perinatal center for the entire state, and infants as well as pregnant mothers at highest risk are referred to our institution. In addition, our early death rate (<12 hours of age) in all live-born extremely low birth weight infants is consistently <2%, indicating greater survival of a population at risk for morbidity. We also did not exclude infants with malformations (some lethal), which may constitute an irreducible component of mortality and morbidity.

Another, and perhaps better, measure of experience would be evaluation of patient outcomes in relation to the actual magnitude of experience each intern or resident has at the time of birth of the neonate. However, marked variations in expertise in residents may be observed for the same magnitude of exposure to patient care, and no preference was given to having more experienced residents or fellows in the NICU earlier in the year. We did not make adjustment for gender or ethnicity, because these patient characteristics remained relatively constant throughout the year. Another limitation is that our study is a single-center study. Our results may not be generalizable to other academic centers with different staffing patterns, care practices, or patient characteristics.

There are several strengths to our study. Mortality was analyzed regardless of cause of death, thus including all instances of mortality within the study period. This serves to better evaluate actual resident efficacy without making arbitrary exclusions for characteristics such as nonviability that might otherwise skew data interpretation. Another strength is the analysis of data by month of birth. Many studies evaluated outcomes from July and August as compared with the rest of the academic year. The rotation of interns through our NICU is organized such that interns may have their first NICU rotation as late as December. Therefore, we included the data by month to show there was no difference, even as interns new to the NICU rotated through. Another strength of our study is the analysis of data over several years permitting the evaluation of not only many infants, but also many different physician care teams.

Other investigators have studied the role of housestaff inexperience and the "July phenomenon." Most reports in the literature do not indicate that care early in the academic year is of lower quality than care later in the year. A study by Barry et al13 found no differences in mortality between the early part of the year and later in the year in adult patients admitted to ICUs at 5 major teaching hospitals. Similarly, Smith et al15 in pediatric neurosurgery patients showed no differences in outcomes of brain tumor or shunt surgeries over the academic year. Borenstein et al21 found no differences in resident errors or error related adverse outcomes between early and late in the academic year on a pediatric surgery service. Claridge et al22 demonstrated no statistical difference in mortality or major morbidities between early and late in the academic year in adult trauma patients. Ford et al23 and Caughey24 found no difference in complications among obstetrical patients when delivery in July was compared with the rest of the academic year. Shulkin25 found no overall differences in adverse events between early and late in the academic year with the exception of a higher incidence of documentation errors early in the year.

However, there is some literature to support the presence of a "July phenomenon." Kestle et al16 examining pediatric neurosurgical shunt placement found a trend toward shorter shunt survival, as well as an increase in complications of shunts placed earlier in the academic year. Rich et al12 found no difference in mortality in 21 679 patients admitted to a single hospital in Minnesota in the 1980s but did find a significant difference in length of stay (0.43 days longer early in the academic year) and cost ($370 more early in the academic year versus later). In a study evaluating housestaff experience in the NICU, Griffith et al17 noted that interns were more likely to order arterial blood gases than a more senior resident. Therefore, there may be differences in care practices and subtle changes in outcomes that may not be apparent on evaluation of mortality or major morbidities. Although morbidity and mortality are important outcome measures, other quality measures such as success with procedures and adherence to guidelines may be areas where improvement in the expertise of residents may be more readily demonstrated.

It is possible that outcomes may be different only during periods of decreased supervision, such as nights and weekends. It is also possible that resident inexperience may become apparent in centers that have a lower degree of supervision, such as absence of in-house supervision by fellows or faculty at night. The trend toward in-house attendings and fellows at night to provide increased supervision may be a factor in preventing the July phenomenon. Additional studies are needed to determine more carefully the effects of varying levels of housestaff expertise on outcomes.

In conclusion, our study demonstrates the absence of a July phenomenon in the NICU. Variations in the level of housestaff experience over the course of the academic year do not seem to affect neonatal morbidity or mortality in academic NICUs, even in premature infants who have a high rate of suboptimal outcomes.


Figure 3
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  		FIGURE 3 IVH grade 3–4 or PVL in infants between 401 and 1500 g by month of birth demonstrating no differences in IVH grade 3 or 4/ PVL rate across the academic year (mean, 95% CI, P = .20, by repeated measures analysis of variance).

 


   FOOTNOTES
 
Accepted Jul 14, 2008.

Address correspondence to Namasivayam Ambalavanan, MD, Department of Pediatrics, 525 New Hillman Bldg, 619 South 20th St, University of Alabama at Birmingham, Birmingham, AL 35249. E-mail: ambal{at}uab.edu

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


What's Known on This Subject

There have been numerous adult trials examining the presence of increased morbidity and mortality early in the academic year. This idea is popularly known as the July phenomenon. There have been limited studies published regarding this phenomenon in children.

 

What This Study Adds

This study demonstrates that mortality and major morbidities did not change over the academic year in an NICU. This suggests that the quality of care of critically ill neonates is not decreased early in the academic year.

 


   REFERENCES
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

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PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics

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