Background and Objectives: There are few data evaluating the role of inpatient rebound bilirubin levels in the management of infants readmitted after their birth hospitalization for indirect hyperbilirubinemia. The goal of the present study was to evaluate the clinical utility of inpatient rebound bilirubin levels within this patient population.
Methods: A retrospective cohort study was conducted of 226 infants readmitted after their birth hospitalization for indirect hyperbilirubinemia. Data from 130 infants with rebound bilirubin levels drawn at a mean of 6.1 ± 2.4 hours after discontinuation of phototherapy were compared with data from 96 infants without rebound bilirubin levels. The primary outcome was readmission to the hospital, and secondary outcomes included length of stay and discharge time. A subgroup analysis compared characteristics of children who required repeat phototherapy versus those who did not.
Results: Overall, 5 of 130 patients from the rebound group were readmitted compared with 4 of 96 patients from the no-rebound group (P = .98). Length of stay was significantly longer for patients with rebound bilirubin levels (27.7 vs 23.2 hours; P = .001). Patients with bilirubin levels lowered to ≤14 mg/dL were less likely to receive repeat phototherapy than those with levels >14 mg/dL (2 of 129 vs 12 of 97; P = .001).
Conclusions: Early inpatient rebound bilirubin levels do not successfully predict which patients will require hospital readmission for repeat phototherapy. Children with bilirubin levels lowered to ≤14 mg/dL with phototherapy are unlikely to receive repeat phototherapy.
The 2004 American Academy of Pediatrics (AAP) guideline on the evaluation and management of hyperbilirubinemia in the newborn infant states that “discharge from the hospital need not be delayed to observe the infant for rebound” bilirubin levels.1 Despite this recommendation, many pediatricians obtain early (4–8 hours) rebound bilirubin levels after discontinuation of phototherapy. There is currently a lack of robust data addressing the value of early (<12 hours) inpatient rebound bilirubin levels; much of the previous research used to create the AAP guideline focused on rebound bilirubin levels that were drawn, on average, ≥12 hours from the cessation of phototherapy.2–6
Although recent research has focused on attempts to improve adherence to AAP guidelines, it is also necessary to provide stronger evidence evaluating the effects of early inpatient rebound bilirubin levels.7 The present study assessed the clinical utility of rebound bilirubin levels for infants readmitted with hyperbilirubinemia after their birth hospitalization. The following outcomes were assessed: subsequent hospital readmission rates, length of stay, discharge time, and re-initiation of phototherapy during a current admission. We hypothesized that inpatient rebound bilirubin levels would not affect readmission rate.
We identified subjects readmitted to Yale−New Haven Children’s Hospital, a tertiary care center with ∼3800 newborns delivered annually. The medical records database was reviewed for infants <10 days of age with International Classification of Diseases, Ninth Revision, codes for a principal diagnosis of jaundice and a principal or secondary procedure of phototherapy between January 2007 and April 2014. Patients were eligible for inclusion if they had a gestational age ≥35 weeks and were readmitted from the newborn nursery for phototherapy treatment of indirect hyperbilirubinemia. Exclusion criteria consisted of: history of phototherapy in the first 24 hours of life, admission to the ICU, exchange transfusion, direct hyperbilirubinemia, and evidence of sepsis at time of admission. If a child had >1 hospitalization with a primary diagnosis of jaundice, only the first encounter was included in the analysis.
Data from children who had inpatient rebound bilirubin levels checked <12 hours after phototherapy cessation (“rebound” group) were compared with those who did not have repeat levels drawn (“no-rebound” group). The decision to check a rebound bilirubin level and the timing of this investigation were determined by the attending pediatrician. Decisions regarding initiation of phototherapy were based on the nomogram from the 2004 AAP guidelines and the 2009 update on the evaluation and management of hyperbilirubinemia in the newborn infant.1,8 Infants were stratified into low-, medium-, or high-risk groups based on presence of risk factors for hyperbilirubinemia/kernicterus. Decisions to implement phototherapy were based on single serum bilirubin levels obtained at the time of admission and the corresponding light level based on hours of life on the nomogram.8 All patients requiring phototherapy received triple light therapy, and no changes in the dosage of phototherapy occurred during the study period.
The primary outcome was readmission for repeat phototherapy within 72 hours of discharge. Secondary outcomes include length of inpatient stay, duration of phototherapy, and hospital discharge time. A separate analysis compared characteristics of patients who required repeat phototherapy (either with readmission or on the same admission) with those patients who did not. Continuous variables in the 2 groups were compared by using the 2-sample t test. We analyzed categorical data by using either the χ2 test or Fischer’s exact test as dictated by sample size. The Yale University Human Investigation Committee provided approval for the review of all medical records.
There were 252 infants identified in the search, and 226 were included in the final analysis (Fig 1). Overall, 130 (58%) of the 226 patients had a rebound bilirubin level checked a mean of 6.1 ± 2.4 hours from phototherapy cessation, and 96 (42%) of 182 patients had no rebound level checked. There were no significant differences in the baseline characteristics between the 2 groups (Table 1). Table 2 displays the bilirubin levels at phototherapy initiation and cessation, as well as the duration of phototherapy. Initial bilirubin levels were higher in the rebound group compared with the no-rebound group, and they were also higher at time of light cessation. The rebound group had a significantly shorter duration of phototherapy (15.1 vs 17.7 hours; P = .008).
Nine (4%) of 226 children in the cohort were readmitted to the hospital for additional phototherapy within 72 hours of discharge, with no significant difference in readmission rates between the rebound and no-rebound groups (Table 3). When only children with risk factors for hemolysis were included in the analysis, 1 (2.9%) of 34 patients from the rebound group were readmitted versus 3 (10%) of 30 from the no-rebound group (P = .3). Mean length of stay was significantly increased in the rebound group, and mean hospital discharge time was significantly later in the rebound group.
Within the rebound group, there was no significant difference in mean rebound bilirubin levels (13.4 mg/dL) versus mean bilirubin levels at the time of phototherapy cessation (13.7 mg/dL; P = .1). Five of the 130 children in the rebound group received repeat phototherapy on the same admission. Overall, 14 (6.2%) of 226 patients required repeat phototherapy (9 readmitted and 5 re-initiated at same admission). Only 2 of these 14 patients adhered to the AAP guideline of lowering bilirubin levels to ≤14 mg/dL before discontinuation of phototherapy. Further analysis revealed that patients in the no-rebound group were significantly more likely to have bilirubin levels lowered to ≤14 mg/dL compared with the rebound group (66 of 96 vs 63 of 130; P = .003). Overall, 2 (1.6%) of 129 infants whose bilirubin level at cessation was ≤14 mg/dL required repeat phototherapy, whereas 12 (12.4%) of 97 whose bilirubin level at cessation was >14 mg/dL required repeat phototherapy (P = .001).
To date, there is a limited amount of research addressing the potential clinical utility of early (<12 hours) rebound bilirubin levels.9–11 In 1999, Del Vecchio et al9 analyzed 48 infants with rebound levels ranging from 6 to 8 hours and found a decrease in average rebound bilirubin level compared with level at cessation of phototherapy. A 2002 retrospective analysis by Al-Saedi10 evaluated 301 infants with rebound bilirubin level times averaging 8.3 ± 5.3 hours and found no significant increase in early rebound bilirubin levels. Our study is in line with this previous research, as we reported no significant increase in early inpatient rebound bilirubin levels drawn at a mean of 6.1 ± 2.4 hours compared with the level at phototherapy cessation. However, to our knowledge, our study is the first to directly compare patients with early rebound bilirubin levels versus those without rebound levels, specifically addressing differences in clinical outcomes such as readmission rates, length of stay, and discharge timing.
Early inpatient rebound bilirubin levels were checked in a majority of infants at our institution, and this practice did not successfully prevent readmission. However, within the rebound group, 5 (3.8%) of 130 patients underwent repeat phototherapy during the same admission. Of these 5 infants, 1 had a cephalohematoma, and 2 had ABO incompatibility with negative results on the Coombs test. Importantly, all of these patients had phototherapy halted at a level >14 mg/dL, with bilirubin levels of 14.7, 15.9, 16.7, 16.8, and 17.6 mg/dL at phototherapy cessation. In cases in which phototherapy was initially continued to reach the AAP recommendation of ≤14 mg/dL, all rebound bilirubin levels remained below the light level for recommended phototherapy.
In the entire cohort, children with bilirubin levels ≤14 mg/dL were much less likely to receive repeat phototherapy than those who had phototherapy discontinued at a level >14 mg/dL. In the 14 children who required repeat phototherapy, 12 had phototherapy discontinued at a level >14 mg/dL. There were only 2 patients who received repeat phototherapy despite adherence to the AAP guideline of lowering the bilirubin to ≤14 mg/dL. Interestingly, one of these patients (originally from the no-rebound group) had a rebound bilirubin level checked on a subsequent hospitalization, and this rebound level still failed to prevent a third hospitalization. He was eventually diagnosed with elliptocytosis. This finding suggests that children who require recurrent phototherapy despite a level at cessation of ≤14 mg/dL may warrant additional evaluation for hemolysis.
Patients in the rebound group had longer lengths of stay and later discharge times, exposing them to potential iatrogenic complications. These patients also received significantly less time under phototherapy than children who did not have a rebound level. Thus, the rebound group spent more time in the hospital but received less total therapy. Keeping these patients under the lights for additional time to lower bilirubin levels to ≤14 mg/dL was more likely to prevent readmission than monitoring them with a rebound bilirubin level.
Furthermore, there was an increase in cost associated with the rebound groups’ prolonged length of stay and extra laboratory testing. Our institution’s financial department provided estimates for hourly hospital charges of approximately $25.00 and $50.00 for serum bilirubin testing. Using these estimates, the rebound bilirubin group averaged approximately $150.00 extra per patient. This cost is further compounded when considering the improvements in patient flow associated with the earlier discharge times observed in the no-rebound group.
The present study’s main limitation was its retrospective design, which provides no concrete way to control for why individual attending physicians chose to check a rebound level in some infants but not in others. We tried to address this limitation by evaluating baseline characteristics that typically influence this decision, and we found no significant differences in these characteristics between the 2 groups. There was a statistically significant difference between bilirubin levels at the time of phototherapy initiation and cessation, implying that the rebound group’s jaundice was more severe than the no-rebound group. However, the significantly shorter period of time under phototherapy for the rebound group argued against this idea, as one would potentially expect patients with more severe conditions to require more phototherapy. In addition, the mean bilirubin levels at initiation of phototherapy did not approach exchange transfusion levels in either group.
Another significant limitation was the study’s relatively small sample size, particularly considering that the primary outcome of hospital readmission was such a rare occurrence. These circumstances made it difficult to obtain the power necessary to definitively detect subtle differences in readmission rates between the 2 groups, and our post hoc power analysis showed our study to be powered at 80% to detect a 12% difference in readmission rates. Before 2007, our institution’s policy was to obtain rebound bilirubin levels on all patients receiving phototherapy, which limited our ability to increase patient recruitment before this time period. After 2007, the hospitalist group adopted the policy of not obtaining rebound bilirubin levels, whereas the majority of community pediatricians continued to obtain rebound bilirubin levels. This clinical environment made the comparison of the 2 groups possible but again did not provide a large enough sample size to afford substantial power to detect subtle differences in an outcome with such a rare occurrence.
In this retrospective study, inpatient rebound bilirubin levels did not affect readmission rates and were associated with an increased length of stay. Overall, patients whose bilirubin level was lowered to ≤14 mg/dL were significantly less likely to require repeat phototherapy. These findings provide further evidence for initiatives aimed at improving adherence to the AAP’s recommendation to continue phototherapy until bilirubin levels are ≤14 mg/dL and to not delay hospital discharge for monitoring of rebound bilirubin levels.
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
FUNDING: No external funding.
POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.
- American Academy of Pediatrics
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