Original Paper Received: August 20, 2013 Accepted after revision: January 7, 2014 Published online: March 1, 2014
Neonatology 2014;105:306–311 DOI: 10.1159/000358373
Plotting Transcutaneous Bilirubin Measurements on Specific Transcutaneous Nomogram Results in Better Prediction of Significant Hyperbilirubinemia in Healthy Term and Near-Term Newborns: A Pilot Study I. Mohamed a A.C. Blanchard a E. Delvin b J. Cousineau b A. Carceller a
Departments of a Pediatrics and b Clinical Biochemistry, CHU Sainte-Justine, University of Montreal, Montreal, Qué., Canada
Key Words Transcutaneous bilirubin · Hyperbilirubinemia · Jaundice · Neonates · Predictive nomogram
Abstract Background: The American Academy of Pediatrics has recommended a systematic assessment before discharge for the risk of severe hyperbilirubinemia. Plotting total serum bilirubin (TSB) or transcutaneous bilirubin (TcB) on a TSB hour-specific nomogram is proposed as a tool for laboratory evaluation. Objectives: The aim of this study was to compare the predictive characteristics, particularly the incidence of false negative rate (FNR), of the practice of plotting TcB values on the TSB hour-specific risk nomogram versus on transcutaneous nomogram. Methods: Paired TSB and TcB measurements were conducted on 141 newborns. Risk of developing significant hyperbilirubinemia was defined as infants with bilirubin level ≥75% on TSB or ≥95% on TcB nomogram. TSB values, plotted on the TSB nomogram of Bhutani et al. [Pediatrics 1999; 103: 6–14], were used as reference. TcB values were plotted on the TSB nomogram and on the transcutaneous nomograms of Maisels and Kring [Pediatrics 2006; 117: 1169–1173] and Fouzas et al. [Pediatrics 2010;125:e52–e57]. Results: Plotting TcB measurements on a TSB nomogram resulted in a trend towards a higher FNR when compared to Maisels’ and Fouzas’ nomograms (18.0/1,000 compared to
© 2014 S. Karger AG, Basel 1661–7800/14/1054–0306$39.50/0 E-Mail [email protected] www.karger.com/neo
10.2/1,000 and 8.6/1,000 respectively). Although not statistically significant, plotting TcB on transcutaneous nomogram resulted in better predictive values with the Fouzas’ nomogram, having the best sensitivity (90.0%) and specificity (87.79%) as well as the highest positive (35.97%) and negative (99.14%) predictive value. Conclusion: Plotting TcB on a TSB nomogram may result in increased rate of FNR and decreased predictive characteristics. The practice of plotting TcB on a TSB nomogram needs further evaluation. © 2014 S. Karger AG, Basel
Introduction
The American Academy of Pediatrics (AAP) recommends that clinicians perform a systematic assessment before discharge of each newborn for the risk of severe hyperbilirubinemia [1–3]. The AAP and the Canadian Pediatric Society (CPS) [1, 4] have proposed an hour-specific total serum bilirubin (TSB) risk nomogram [2] as a predictive tool. The AAP recommends measurement of the bilirubin level using TSB or transcutaneous bilirubin (TcB) and plotting the results on the risk nomogram [2]. TSB measurement is an invasive procedure; point-ofcare TcB testing is noninvasive and provides instantaneous information, decreasing the likelihood of missing clinically significant hyperbilirubinemia [5–8]. Results from difAna Carceller, MD Department of Pediatrics, CHU Sainte-Justine, University of Montreal 3175 Chemin Côte Sainte-Catherine Montreal, QC H3T 1C5 (Canada) E-Mail ana_carceller @ ssss.gouv.qc.ca
Downloaded by: Kellogg Health Sciences Libr. 129.173.72.87 - 10/9/2014 11:21:55 PM
Methods Study Population and Design The CHU Sainte-Justine in Montreal is a tertiary, motherchild, university-affiliated hospital with an average of 4,000 deliveries/year, with levels 1–3 neonatal care units. We reviewed the existing health records of patients during 5 random weeks (June– September 2008). Our routine nursery protocol includes TSB performed at the time of the routine metabolic newborn screening at 48 ± 12 h of life, although during the period study we routinely performed paired TSB-TcB measurements. Inclusion Criteria We included healthy newborns ≥35 weeks of gestation and ≥2,000 g of weight who had both TSB and TcB measured at a maximum interval of 2 h. The Institutional Review Board for Research in Human Subjects approved this cross-sectional study.
We did not exclude newborns who needed phototherapy after bilirubin testing or who were known for other risk factors such as ABO or Rh incompatibility. Study Instruments Blood specimens were collected at room temperature in 700-μl plastic capillary tubes with a separator gel and coated with balanced lithium-heparin, which were then centrifuged and analyzed within the next hour using the bilirubin oxidase method on a multi-analyzer (LX-20®, Beckman-Coulter, Brea, Calif., USA). When collected in 125-μl capillaries they were used for whole blood bilirubin measurement on a blood gas analyzer (ABL 835, Radiometer, Copenhagen, Denmark). TcB was measured using BiliCheck® (SpectRx Inc., Galveston, Tex., USA) based on spectral analysis. After performing the calibration, and following the manufacturer’s recommendations [21], BiliCheck was preset against the infant’s forehead or sternum, and the device gave a result representing the average of five consecutive readings. Collection of Data We collected only the first pair of simultaneous TcB and TSB measurements for each patient. Upon inclusion into the study, the demographics and clinical characteristics of the mothers and newborns were taken. Definitions – At 48 h of life, the 95th percentile curves in the nomogram of Maisels and Kring (171 μmol/l; 10 mg/dl) [9] and Fouzas et al. (188.1 μmol/l; 11 mg/dl) [10] coincides with the 75th percentile curve in the nomogram of Bhutani et al. (188.1 μmol/l; 11 mg/dl) [2]. – True positive cases: TcB measurements ≥75th percentile on the TSB nomogram or ≥95th percentile on Maisels’ or Fouzas’ nomogram confirmed with TSB ≥75th percentile on the TSB nomogram. – True negative cases: TcB
Neonatology 2014;105:306–311 DOI: 10.1159/000358373
Plotting Transcutaneous Bilirubin Measurements on Specific Transcutaneous Nomogram Results in Better Prediction of Significant Hyperbilirubinemia in Healthy Term and Near-Term Newborns: A Pilot Study I. Mohamed a A.C. Blanchard a E. Delvin b J. Cousineau b A. Carceller a
Departments of a Pediatrics and b Clinical Biochemistry, CHU Sainte-Justine, University of Montreal, Montreal, Qué., Canada
Key Words Transcutaneous bilirubin · Hyperbilirubinemia · Jaundice · Neonates · Predictive nomogram
Abstract Background: The American Academy of Pediatrics has recommended a systematic assessment before discharge for the risk of severe hyperbilirubinemia. Plotting total serum bilirubin (TSB) or transcutaneous bilirubin (TcB) on a TSB hour-specific nomogram is proposed as a tool for laboratory evaluation. Objectives: The aim of this study was to compare the predictive characteristics, particularly the incidence of false negative rate (FNR), of the practice of plotting TcB values on the TSB hour-specific risk nomogram versus on transcutaneous nomogram. Methods: Paired TSB and TcB measurements were conducted on 141 newborns. Risk of developing significant hyperbilirubinemia was defined as infants with bilirubin level ≥75% on TSB or ≥95% on TcB nomogram. TSB values, plotted on the TSB nomogram of Bhutani et al. [Pediatrics 1999; 103: 6–14], were used as reference. TcB values were plotted on the TSB nomogram and on the transcutaneous nomograms of Maisels and Kring [Pediatrics 2006; 117: 1169–1173] and Fouzas et al. [Pediatrics 2010;125:e52–e57]. Results: Plotting TcB measurements on a TSB nomogram resulted in a trend towards a higher FNR when compared to Maisels’ and Fouzas’ nomograms (18.0/1,000 compared to
© 2014 S. Karger AG, Basel 1661–7800/14/1054–0306$39.50/0 E-Mail [email protected] www.karger.com/neo
10.2/1,000 and 8.6/1,000 respectively). Although not statistically significant, plotting TcB on transcutaneous nomogram resulted in better predictive values with the Fouzas’ nomogram, having the best sensitivity (90.0%) and specificity (87.79%) as well as the highest positive (35.97%) and negative (99.14%) predictive value. Conclusion: Plotting TcB on a TSB nomogram may result in increased rate of FNR and decreased predictive characteristics. The practice of plotting TcB on a TSB nomogram needs further evaluation. © 2014 S. Karger AG, Basel
Introduction
The American Academy of Pediatrics (AAP) recommends that clinicians perform a systematic assessment before discharge of each newborn for the risk of severe hyperbilirubinemia [1–3]. The AAP and the Canadian Pediatric Society (CPS) [1, 4] have proposed an hour-specific total serum bilirubin (TSB) risk nomogram [2] as a predictive tool. The AAP recommends measurement of the bilirubin level using TSB or transcutaneous bilirubin (TcB) and plotting the results on the risk nomogram [2]. TSB measurement is an invasive procedure; point-ofcare TcB testing is noninvasive and provides instantaneous information, decreasing the likelihood of missing clinically significant hyperbilirubinemia [5–8]. Results from difAna Carceller, MD Department of Pediatrics, CHU Sainte-Justine, University of Montreal 3175 Chemin Côte Sainte-Catherine Montreal, QC H3T 1C5 (Canada) E-Mail ana_carceller @ ssss.gouv.qc.ca
Downloaded by: Kellogg Health Sciences Libr. 129.173.72.87 - 10/9/2014 11:21:55 PM
Methods Study Population and Design The CHU Sainte-Justine in Montreal is a tertiary, motherchild, university-affiliated hospital with an average of 4,000 deliveries/year, with levels 1–3 neonatal care units. We reviewed the existing health records of patients during 5 random weeks (June– September 2008). Our routine nursery protocol includes TSB performed at the time of the routine metabolic newborn screening at 48 ± 12 h of life, although during the period study we routinely performed paired TSB-TcB measurements. Inclusion Criteria We included healthy newborns ≥35 weeks of gestation and ≥2,000 g of weight who had both TSB and TcB measured at a maximum interval of 2 h. The Institutional Review Board for Research in Human Subjects approved this cross-sectional study.
We did not exclude newborns who needed phototherapy after bilirubin testing or who were known for other risk factors such as ABO or Rh incompatibility. Study Instruments Blood specimens were collected at room temperature in 700-μl plastic capillary tubes with a separator gel and coated with balanced lithium-heparin, which were then centrifuged and analyzed within the next hour using the bilirubin oxidase method on a multi-analyzer (LX-20®, Beckman-Coulter, Brea, Calif., USA). When collected in 125-μl capillaries they were used for whole blood bilirubin measurement on a blood gas analyzer (ABL 835, Radiometer, Copenhagen, Denmark). TcB was measured using BiliCheck® (SpectRx Inc., Galveston, Tex., USA) based on spectral analysis. After performing the calibration, and following the manufacturer’s recommendations [21], BiliCheck was preset against the infant’s forehead or sternum, and the device gave a result representing the average of five consecutive readings. Collection of Data We collected only the first pair of simultaneous TcB and TSB measurements for each patient. Upon inclusion into the study, the demographics and clinical characteristics of the mothers and newborns were taken. Definitions – At 48 h of life, the 95th percentile curves in the nomogram of Maisels and Kring (171 μmol/l; 10 mg/dl) [9] and Fouzas et al. (188.1 μmol/l; 11 mg/dl) [10] coincides with the 75th percentile curve in the nomogram of Bhutani et al. (188.1 μmol/l; 11 mg/dl) [2]. – True positive cases: TcB measurements ≥75th percentile on the TSB nomogram or ≥95th percentile on Maisels’ or Fouzas’ nomogram confirmed with TSB ≥75th percentile on the TSB nomogram. – True negative cases: TcB
