|Year : 2017 | Volume
| Issue : 4 | Page : 213-219
Evaluation of transcutaneous bilirubinometry in term neonates at Lagos State University Teaching Hospital, Ikeja, Lagos
Oyejoke Oyapero, O Fidelis Njokanma, E Aruma Disu
Department of Paediatrics, Lagos State University Teaching Hospital, Ikeja, Lagos, Nigeria
|Date of Web Publication||17-Oct-2017|
Department of Paediatrics, Lagos State University Teaching Hospital, Ikeja, Lagos
Source of Support: None, Conflict of Interest: None
Background: Serum bilirubin can be estimated using a technique that is real-time, noninvasive, painless, fast, and relatively inexpensive technique which is transcutaneous bilirubinometry (TcB). There is a paucity of published research data in Nigeria on TcB, and the aim of this study was to determine the correlation of TcB with total serum bilirubin (TSB) and in a group of term Nigerian neonates at Lagos State University Teaching Hospital (LASUTH) using the Konica Minolta JM-103. Materials and Methods: One hundred and fifty neonates were consecutively recruited at LASUTH, and detailed sociodemographic and clinical information was recorded with an interviewer-administered questionnaire. TcB readings were taken on the forehead, sternum, and abdomen of the calm neonate in a supine position, and blood samples for TSB estimation were drawn from a peripheral vein within 10 min of TcB measurement. Results: Eighty-nine (59.3%) neonates were male; 129 (86%) neonates were of 37–39 weeks' gestational age while 56 (37.3%) presented in the clinic after 48 h of life. Over 83% of the neonates had TcB values that were higher than TSB values, and the percentage of neonates with TSB values > 12 mg/dl was 45.2% compared with 56.8% obtained by TcB. The correlation of TcB with TSB using the Pearson's correlation was positive (r = 0.924). The mean error of TcB compared with the TSB level was independent of gender, gestational age, age at presentation, or birth weight. The measured bias by the Bland and Altman method was 0.97 mg/dl (95% confidence interval: 0.74–1.21) while imprecision was ± 2.96 mg/dl. The best correlation at the forehead was r = 0.928. Conclusion: Excellent correlation of TcB with TSB was obtained from this study, and it is envisaged that further researches will be carried out in dark skinned neonates and that the use of the JM-103 will be widely adopted as a screening tool in Nigeria.
Keywords: JM-103, neonatal jaundice, total serum bilirubin, transcutaneous bilirubinometry
|How to cite this article:|
Oyapero O, Njokanma O F, Disu E A. Evaluation of transcutaneous bilirubinometry in term neonates at Lagos State University Teaching Hospital, Ikeja, Lagos. J Clin Neonatol 2017;6:213-9
|How to cite this URL:|
Oyapero O, Njokanma O F, Disu E A. Evaluation of transcutaneous bilirubinometry in term neonates at Lagos State University Teaching Hospital, Ikeja, Lagos. J Clin Neonatol [serial online] 2017 [cited 2017 Nov 24];6:213-9. Available from: http://www.jcnonweb.com/text.asp?2017/6/4/213/216903
| Introduction|| |
Jaundice is a clinical description of the yellowish discoloration of the sclera of the eyes, skin, and mucous membranes or the visible manifestation of elevated serum bilirubin. Most neonates develop some level of physiological jaundice within the 1st week of life, usually not higher than 12 mg/dl and the baby is otherwise well. Excessive rise in the level of unconjugated bilirubin is, however, of great clinical concern because this form of bilirubin is neurotoxic and result in death or lifelong neurological sequelae. Severe neonatal jaundice has been estimated to occur in up to 10% of newborns, and it is a significant cause of mortality and morbidity in Africa and specifically in Nigeria.,,
Recent global estimates suggest that every year, about 1.1 million babies would develop severe neonatal jaundice with or without bilirubin encephalopathy worldwide and the vast majority reside in sub-Saharan Africa and South Asia. Studies from poorly resourced countries suggest that severe neonatal jaundice represents perhaps the largest unrecognized cause of neonatal morbidity and mortality in the world. The need to prevent bilirubin-induced neurologic damage necessitates repeated blood withdrawal to ascertain bilirubin levels. If resources were invested in a testing strategy that was effective in reducing the number of cases of bilirubin encephalopathy annually, it would result in direct and indirect cost savings. It is thus appropriate to have a reliable and rapid method for the determination of the level of serum bilirubin in neonates.
Visual inspection of the skin, sclera, and mucous membranes is a rapid technique for estimating bilirubin concentration and documenting the cephalocaudal progression of jaundice. Unfortunately, this method is frequently inaccurate, especially when applied to newborns of diverse racial backgrounds. Total serum bilirubin (TSB) level assessment in a clinical laboratory is the gold standard and the most objective method of bilirubin assessment, but the results provided are not real time. The necessary blood sampling is also painful and associated with the possibility of local infection, discomfort, interruption to breastfeeding, and maternal distress.,,
The availability of transcutaneous bilirubinometry (TcB) which measures bilirubin concentration in dermal and subcutaneous tissues has made it possible to obtain serial, noninvasive, and painless measurements. Several investigators have recommended their use as a screening device to detect jaundice and thus decrease the need for frequent blood sampling in the well term infant,,, and its use can reduce the number of hospital readmissions of infants with neonatal jaundice. Although some studies with TcB have shown good correlations with TSB measurements,,, the hope that such measurements would be independent of race has not been fulfilled due to the dearth and equivocal findings of research in dark skinned infants.,, Some studies found uniform correlation between TcB and TSB measurements in neonates with varying degrees of skin pigmentation. while some other researchers observed better correlation in Caucasian neonates.,
There is a paucity of published research data in Nigeria on the correlation between TcB and TSB, and most hospitals in Nigeria still routinely screen their patients by the invasive venous blood sampling. Some of the few Nigerian studies like that by Slusher et al. using the BiliCheck device and by Kayode-Adedeji et al. using the Konica Minolta JM-103 obtained a good correlation between TcB and TSB, but further research is desirable. Furthermore, the commonly used sites that showed good correlation with TSB are the forehead and the upper end of the sternum,, and no Nigerian study had used the abdominal site. The aim of this study, therefore, was to determine the correlation of TcB with TSB at three different sites in term neonates at Lagos State University Teaching Hospital (LASUTH) using the Konica Minolta JM-103.
| Materials And Methods|| |
This prospective descriptive study on the correlation of TcB with TSB in neonatal patients was done at LASUTH.
Study setting and location
The study was conducted at the neonatal wards of LASUTH, Ikeja, Lagos, Nigeria. LASUTH is a tertiary health facility situated in the capital of Lagos State and funded by the Lagos State Government. It is a multispeciality hospital with a bed complement of 741, with about 110 pediatric beds of which nearly half are for neonates.
Consecutive patients that presented at the neonatal unit of the hospital were recruited for the study. Patients who were selected were further screened for inclusion in the study after checking them with set inclusion and exclusion criteria.
Sample size determination
This was determined using the formulae: N = Z pq/d 2. Using a prevalence of neonatal jaundice of 26.5% in a previous study, a sample size of 150 neonates was determined.
Term neonates with gestational age of 37 completed weeks and above (determined on the basis of the date of the last menstrual period or first-trimester ultrasound findings) and with a birth weight not <2500 g that presented with jaundice or deemed to have jaundice by the attending physician were included in the study. Excluded were those who may require urgent emergency treatment and those with any skin bruising, local nevus, hemangioma, or melanotic patch on the forehead, sternum, or abdomen which could affect the accuracy of TcB readings. Similarly, those whose parents were unwilling to give their informed consent and did not want to participate in the study, and neonates whose bilirubin values were unrecordable with the JM-103™ due to their high level of jaundice were also excluded from the study. (TcB values were unrecordable above 19.6 mg/dl).
The protocol and procedures of the study were presented to the Health Research and Ethics Committee of LASUTH and approval was obtained. The parents of the participating neonates were given a written informed consent form. The form gave a plain language description of the study, the names and affiliation of investigators, the right to withdraw at any time, the ethics committee approval, and the privacy guarantee.
At contact after obtaining an informed consent, an interviewer-administered questionnaire was used to obtain the parents' medical, social, and behavioral information. The neonate's gestational age at birth, postnatal age at the time of TcB, and the mother's ethnicity were recorded for each neonate. The neonates' detailed medical history and physical examination findings were also recorded, and a provisional clinical diagnosis was made.
All the TcB readings were done by the investigator using Konica Minolta Jaundice Meter, JM-103™ (Daisennishimachi, Sakaiku, Osaka, Japan). The readings were taken on the forehead, sternum, and abdomen of the calm neonate in a supine position. The forehead reading was taken 2 cm above the glabella with the eyes shielded while taking the readings. The abdominal readings were taken 3 cm above the umbilicus while the sternal reading was taken at the mid-point of the sternum. The probe was disinfected with 70% isopropyl alcohol after using it on each baby. The readings over each measurement site were displayed as the TcB level in mg/dl. An average value of three readings from each site in mg/dl was recorded.
Total serum bilirubin estimation
The blood samples for the TSB were obtained by the investigator in the neonatology units. Blood samples for TSB estimation were drawn from a peripheral vein within 10 min of TcB measurement and transferred into heparinized specimen bottles. The bottles were placed in a light proof box and transferred to the laboratory immediately for total bilirubin determination. TSB levels were measured in the hospital's clinical chemistry laboratory using Beckman Coulter Synchron CX5® Automated Chemistry Analyzer by the Diazo method. The machines for TSB measurements were calibrated daily according to the manufacturers' recommendations using a commercially available control serum supplied with the machine by the medical laboratory scientist to ensure accuracy and consistency of the results obtained. The values obtained from the laboratory result were recorded for each patient.
Data were analyzed using Statistical Package for Social Sciences for Windows (version 20. Chicago, IL, USA). Frequency distribution tables were generated, and measures of central tendency and dispersion were computed for numerical variables. Since the data were normally distributed, descriptive statistics including means, standard deviations (SDs), and percentages were used in data analysis. The Chi-square test was used to determine the level of association between the categorical variables. Significant level of neonatal jaundice was set at 12 mg/dl. The means of TcB readings and TSB levels were compared using paired Student's t-test and ANOVA test. Pearson's correlation analysis with linear regression was done to test the relationship between TSB and TcB values as well as for TcB measurements taken at different sites.
Analysis of covariance (ANCOVA) for repeated measures was also used to compare the agreement between TcB and TSB measures. Mean bias and imprecision of TcB compared with TSB measurement were calculated using the method of Bland and Altman. This was used to determine the level of agreement between TcB and TSB and to overcome the limitation associated with correlation analysis. The mean bias was defined as the mean difference between each paired TcB and TSB measurement. Imprecision was defined ±2 SD from the mean difference. Limits of agreement of the mean differences were given as 95% confidence intervals (CIs). A 5% level of significance was adopted.
| Results|| |
A total of 150 neonatal subjects who were eligible by set inclusion and exclusion criteria and whose parents gave their informed consent were included in the study. All neonates were included in the final analysis. Of 150 eligible neonates, 89 (59.33%) were male and 61 (40.67%) were female. Most of the neonates (129; 86%) were of 37–39 weeks' gestational age while others were 40–42 weeks. About one-third (56; 37.33%) presented in the clinic between 24 and 48 h of life with neonatal jaundice [Table 1].
Sixty-eight (45.33%) neonates had bilirubin values >12 mg/dl using the TSB compared to 85 (56.67%) determined by TcB. The mean TSB was 12.26 ± 3.65 while the mean TcB was 13.25 ± 3.60. Majority of the neonates (125; 83.34) had TcB values >TSB, and the difference between TcB and TSB readings was between 0 and 0.9 mg/dl in most of the neonates [Table 2].
|Table 2: Bilirubin values of the study neonates determined with transcutaneous bilirubinometry and total serum bilirubin|
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[Table 3] shows a comparison of the two methods of bilirubin measurements by neonatal characteristics and the level of agreement between the two methods using the ANCOVA. The P value for gender was 0.364 while that for age at presentation was 0.070.
|Table 3: Comparisons of the two bilirubin measurement methods by the study variables using analysis of covariance|
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[Figure 1] shows the relationship between the mean TcB measurement and TSB. Using linear regression analysis, the correlation of TcB with TSB was 0.924 (P = 0.000). The linear relationship between the two is described by the equation TSB = TcB × 0.93. This Figure shows the correlation value between TSB and mean TcB.
|Figure 1: Pearson's correlation of total serum bilirubin with mean transcutaneous bilirubinometry|
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[Figure 2] shows the error distribution (Bland and Altman) of TcB and TSB. The X-axis shows the mean TSB + mean TcB in mg/dl and the Y-axis shows the difference between TSB and TcB in mg/dl. Mean difference between the two assays was 0.97 mg/dl (95% CI: 0.74–1.21). The imprecision was ± 2.96 mg/dl.
|Figure 2: Error distribution (Bland–Altman plot) between the difference of total serum bilirubin-transcutaneous bilirubinometry and the mean total serum bilirubin + mean transcutaneous bilirubinometry|
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| Discussion|| |
Of the 150 newborns studied, the mean TcB score was 13.25 ± 3.60 while the mean TSB was 12.26 ± 3.65. The mean TSB value obtained was lower than bilirubin values recorded with TcB in the current study. The highest TcB recording (13.46 ± 3.68) was obtained on the abdomen while the lowest reading (13.05 ± 3.81) which was closest to the TSB reading was obtained on the forehead. The sociodemographic profile of the neonates in this study was similar to that observed by other researchers as 59.33% were male and 40.67% were female., It is, however, significant to note that 70.67% of the study neonates were delivered at general hospitals. This is not surprising because most general hospitals are government owned and do not charge much money like private hospitals and thus attend predominantly to the low socioeconomic groups in the population.
The difference between the bilirubin values measured with TcB and TSB was small, with most of the neonates having a difference that was <0.9 mg/dl. Over 83% of the neonates had TcB values that were higher than TSB values, and the percentage of neonates with bilirubin values TSB values >12 mg/dl was 45.2% compared with 56.8% obtained by TcB. This indicates that higher values of bilirubin are obtained when Minolta JM-103 is used for screening. This is in agreement with a recent Nigerian study by Kayode-Adedeji et al. Maisels et al. also reported that higher values of bilirubin were detected by TcB using JM-103 compared to TSB in dark skinned neonates. This is, however, in contrast to the observation by other researchers , who obtained lower values when JM-103 is used to determine TcB. Samanta et al., however, recorded lower values with TcB compared to TSB in healthy term and preterm neonates while some other researchers  reported higher values using the BiliCheck device. These results when compared to that obtained in the index study show a variable but consistently close association between TcB and TSB. The practical implication of this observation is a probable slight increase in the rate of interventions with phototherapy if only the TcB readings were used for the assessment of the severity of jaundice and in clinical decision-making.
The first method of comparison between TSB and TCB using the ANCOVA indicated that none of the neonatal variables measured was a significant contributor to TcB correlation error with TSB. The level of agreement between TcB and TSB is thus independent of the neonate's gender, age at presentation, gestational age, or birth weight. Similarly, correlation of TcB with TSB using the Pearson's correlation coefficient with linear regression analysis shows a positive association between TcB and TSB scores. This was in agreement with evidence from previous screening accuracy studies indicating a strong association between TcB and TSB measurements, with correlation coefficients ranging from 0.75 to 0.95.,, TcB measurements have demonstrated linear correlation with TSB, and several investigators have recommended their use as a screening device to detect clinically significant jaundice and thus decrease the need for frequent blood sampling in the term neonates.,,,
The mean difference between TSB and mean TcB using the Bland and Altman method was 0.97 mg/dl while the imprecision was ±2.96 mg/dl. This shows that the average discrepancy between TSB and TcB is small and that clinically, this difference is not large enough to be important or negatively influence the screening result of the patient. This imprecision was lower than ±7.6 mg/dl obtained by Slusher et al. using the BiliCheck device. The percentage difference in the bilirubin values obtained at the forehead, sternum, and abdomen was 6.4%, 8.1%, and 9.7%, respectively. A comparison of the correlation values obtained at the three body sites shows that the best correlation was obtained at the forehead with a correlation coefficient of 0.928. The error distribution for the forehead showed that the mean difference between the two assays was 0.87 mg/dl while the imprecision was ±2.93 mg/dl. At the sternal site of measurement, a correlation of 0.907 was obtained while the error distribution for the sternum showed that the mean difference between the two assays was 1.08 ± 1.58 mg/dl while the imprecision was ±3.15 mg/dl.
These findings are in agreement with the study by Randeberg et al., Rubaltelli et al., and other researchers  who found that transcutaneous readings taken from the forehead correlated more with bilirubin measured in serum compared with transcutaneous measurements taken other sites. Maisels et al., however, observed a better correlation with TSB when TcB measurements were performed on the sternum (r = 0.953) compared with the forehead (r = 0.914). The consensus of most investigators, however, is that the average score of the forehead and sternal readings provide a better correlation with TSB. The lowest correlation was obtained on the abdomen (r = 0.886). The error distribution for the abdomen was 0.67 mg/dl while the imprecision was ±3.58 mg/dl. Abdominal readings were not routinely done by other researchers, thereby hampering comparisons. The low level of imprecision obtained from this site may, however, make it an alternative in rare cases of bruises or hemangioma on the forehead or sternum.
The goal of screening for neonatal jaundice is to promote early identification and treatment and to avoid severe neonatal jaundice and bilirubin encephalopathy, while at the same time preventing the overtreatment of newborns, whose bilirubin levels will resolve without treatment. TcB measurement appears to be a useful and reliable index for estimating TSB levels in dark-skinned neonates. Universal predischarge neonatal screening with TcB measurements has become a common practice throughout the world. This cannot, however, be said of resource-limited countries like Nigeria where the routine use of the invasive TSB screening is still commonly done. The relatively simple and noninvasive TcB measurements can be an important adjunct in preventing the high incidence of bilirubin-induced morbidity and mortality in low-technology clinical environments, especially the Konica Minolta JM-103 does not require replacement tips, which are associated with a high maintenance cost after the initial purchase of the device.
| Conclusion|| |
The difference between the bilirubin values measured with TcB and TSB was low, with most of the neonates (69.33%) having a difference that was <0.9 mg/dl. Correlation of TcB with TSB using the Pearson's correlation coefficient was strongly positive in this cohort of Nigerian children. A comparison of the three measurements sites obtained the best correlation on the forehead while the least correlation was obtained on the abdomen. This study has shown that there is a strong correlation between TcB and TSB and that the agreement between TSB and TcB was independent of the neonate's gender, age at presentation, gestational age, and birth weight. Health facilities across the country should widely adopt the use of the TcB device.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]