Indian J Pediatr DOI 10.1007/s12098-015-1688-4
ORIGINAL ARTICLE
Challenges of Implementing Universal Newborn Hearing Screening at a Tertiary Care Centre from India Shuchita Gupta & Sandhya Sah & Tapas Som & Manju Saksena & Chander Prakash Yadav & M. Jeeva Sankar & Alok Thakar & Ramesh Agarwal & Ashok K. Deorari & Vinod K. Paul
Received: 7 June 2014 / Accepted: 1 January 2015 # Dr. K C Chaudhuri Foundation 2015
Abstract Objectives To report experience of implementing universal newborn hearing screening (UNHS) in a tertiary care neonatal unit, identify risk factors associated with failed two-step automated acoustic brainstem response (AABR) screen and evaluate cost of AABR. Methods This was a prospective study of UNHS outcomes of all live births with two step AABR using BERAphone MB11®. Outcome measures were screening coverage, refer, pass and lost to follow up rates and cost of AABR using micro-costing method. To identify risk factors for failed screening, authors performed multivariate logistic regression with failed two-step AABR screen as dependent variable and baseline risk factors significant on univariate analysis as predictors. Results Screening coverage was moderate (84 %), with 2265 of total 2700 eligible infants screened with initial AABR (mean gestation 37.2±2.3 wk; birth weight 2694±588 g; 305 received nursery care). A total of 273 of 2265 infants were “refer” on first screen. Second screen was done on 233, of which 58 were “refer”. Of these, 35 underwent conventional ABR, of which 5 were diagnosed to have hearing impairment. Only 2 could get hearing aid. Overall, a total of 2197 (81.4 %) infants passed, 496 (18.4 %; excluding 2 deaths) were lost to follow up at various stages, and S. Gupta : S. Sah : T. Som : M. Saksena : M. J. Sankar : R. Agarwal (*) : A. K. Deorari : V. K. Paul Newborn Health Knowledge Centre (NHKC), Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India e-mail: [email protected] C. P. Yadav Department of Biostatistics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India A. Thakar Department of ENT, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
5 (0.2 %) were diagnosed with hearing impairment, all of whom were high risk. Average cost of AABR was INR 276 per test. No factor emerged as significant on multivariate analysis. Conclusions UNHS is feasible to implement, but significant lost to follow up and non-linkage with appropriate rehabilitation services limit its utility. Cost effectiveness of UNHS compared to high risk based screening needs to be determined. Keywords Universal newborn hearing screening . Automated acoustic brainstem response
Introduction World Health Organization recognizes universal newborn hearing screening (UNHS) using either oto-acoustic emissions (OAEs) or automated auditory brainstem response (AABR) as a goal for all countries and communities with available rehabilitation services [1]. There is also a recent upsurge on the reporting of data on UNHS from many centers in India [2–4], thus implying the relative importance of this issue in recent time in most neonatal settings. However, there is limited data on the cost-effectiveness of UNHS using various approaches, especially at places where there is no system linking the screening and diagnostic assessments with appropriate rehabilitation services, which still remains a challenge in the best of set-ups. Therefore, for any neonatal unit, especially those currently performing high risk based hearing screening, it is important to understand the challenges and cost-effectiveness of implementing UNHS, before formulating a policy on the same. The present study was undertaken to objectively evaluate the feasibility and cost of implementing UNHS at a tertiary care neonatal unit, in order to inform decision on continuing
Indian J Pediatr
this program in the authors set up and implementation of the same across other such units in the country.
RUP is the predetermined estimated cost for providing a unit of healthcare service, from the hospital perspective.
Material and Methods The present data was collected prospectively as part of the UNHS initiated at the tertiary care neonatal unit of All India Institute of Medical Sciences (AIIMS), Delhi, India from May 2011 through June 2012. All live births during the study period were eligible for hearing screening. The main outcome measures were screening coverage by a single specialist staff, refer and loss to follow up rate, and the cost of AABR procedure using micro-costing method. The risk factors associated with a two step failed AABR screen were also assessed. All eligible infants were screened using a two step automated auditory brainstem response (AABR) by BERAphone MB11®. The first screen was done when the baby was stable, preferably between 24 to 48 h of birth, ensuring that preterm infants born at ≤32 wk of gestation were not screened before 34 wk of postmenstrual age [5]. Those infants who had a “refer” result on the first screen (either unilateral or bilateral) were re-screened within one week. The second screen was performed on both the ears even if the initial screen had only unilateral refer result, according to the guidelines of the Joint Committee on Infant Hearing (JCIH) [6]. Infants who were “refer” on the second screen (either unilateral or bilateral), were referred for a conventional ABR in the Department of ENT. All parents were counseled with regard to the importance and implications of the screening results, allaying undue anxiety while also stressing the need for follow up. AABR was performed using BERAphone MB11® in a quiet room devoid of any electromagnetic fields influence, during natural sleep. Acoustical CE-chirp stimuli were applied with high repetition rate of 93 clicks per second with an acoustic spectrum which is flat 750–5000 Hz. The skin around the patient’s ear was cleaned and small quantity (0.1–0.2 mL) of electrode-gel was applied at electrode sites. BERAphone headset was placed so that the respective electrodes were placed at their recommended positions on the forehead, mastoid and vertex. An impedance test was then performed to confirm correct position of the electrodes. Thereafter, if the indicator line reached the pass threshold within 3 min (180 s), test result was “pass”, otherwise; “refer”. A maximum of two attempts were allowed at each ear. A repeat AABR was performed within a week if the initial test result was “refer”. If the repeat AABR was also “refer”, then the baby was considered to have failed the two step AABR screening. Total cost for AABR was assessed based on micro costing method calculating the cost of the reference unit price (RUP).
Cost o f RUP ¼
ðBasic costs o f doing test þ incurred actual recurrent costs*Þ Total number o f tests during speci f ied period
*Basic costs include capital costs o f the building; annuitized equipment costs and costs o f f ixed assets; while incurred recurrent costs include costs incurred due to consumption o f human resources like salaries; various stores and electricity
The total annual cost of AABR was first calculated by adding the basic costs and then adding the incurred actual recurrent costs for doing all AABR tests during one year period. The basic costs consisted of the capital costs of the building, annuitized equipment costs and the costs of fixed assets. The incurred actual recurrent costs consisted of the costs of human resources (salaries), various stores and electricity [7]. The cost of RUP, i.e., cost of doing one AABR test was then estimated by dividing the total annual cost by the total number of tests during one year period (considering an average of approximately 170 tests per month), thereby providing the cost of a single test. Since the basic cost was calculated in the year 2009–10, the cost was adjusted for the year of study using inflation index of 2011–12. A systematic record of all babies being delivered at authors’ unit is maintained in an electronic database in MS Access which includes all important maternal, antenatal and perinatal details for any infant, along with details of hospital stay, major morbidities and treatment received. Weekly appraisal, quality checks and supervision of the database is done by an independent scientist. The results of the screen are also recorded and printed in the final discharge summary of the baby. All the baseline details, along with the major risk factors and details of hospital stay including NICU stay were imported from this database into STATA 11.0 (College Station, Texas, USA), checked for inaccuracies and inconsistencies and then analyzed. For risk factors, the authors did multivariate logistic regression with failed two-step AABR screen as dependent variable and baseline risk factors significant on univariate analysis as predictors. Analysis of risk factors was done using STATA 11.0. Results There were a total of 2765 live births during the study period, of which 2700 infants were discharged. Of the 2700 infants discharged, 431 were discharged before the first AABR could be done, 3 had pacemaker in situ and parents refused for screening in one. The initial AABR screen, therefore could be done in 2265 infants (Fig. 1). The screening coverage was 84 % among the infants discharged (2265/2700), while the refer rate following the
Indian J Pediatr Total live births, n=2765 Death, n=55; Refer to other unit, n=4; LAMA, n=6 Total discharged, n=2700
Discharged prior to test,
Initial AABR done, n=2265
n=431; Others, n=4
Pass, n=1992
Refer, n=273
Loss to follow up, n=39; Death, n=1
II AABR, n=233
Pass, n=175
Refer, n=58
Loss to follow up, n=22; Death, n=1
Conventional ABR, n=35
Pass, n=30
Refer, n=5
Fig. 1 Patient flow. AABR Automated Auditory Brainstem Response; LAMA Left against medical advice
second AABR screening was 2.1 % (58/2700), though it is limited by the fact that not all the infants “refer” on the initial AABR could be subjected to the second AABR screen. The distribution of major risk factors among infants who were screened with first AABR is shown in Table 1. The cost of AABR per test was INR 276 (Table 2) Table 1
Baseline details and risk factors in screened population
Variable
AABR done, n=2265 (%)
Gestation≤32 wk Mean ± SD Birth weight≤1500 g Mean ± SD Small for gestational age Multiple births Received nursery care>12 h Hypoxic ischemic encephalopathy Seizures Mechanical ventilation Intraventricular hemorrhage Down syndrome Systemic sepsis Hyperbilirubinemia requiring treatment
117 (5.2) 37.2±2.3 103 (4.5) 2694±588 134 (5.9) 150 (6.7) 305 (13.5) 20 (0.9) 8 (0.4) 44 (2.0) 8 (0.4) 4 (0.2) 51 (2.3) 282 (12.5)
On univariate analysis of various risk factors for a “refer” result on two step AABR, lower gestation, nursery care, systemic sepsis and mechanical ventilation were significant. On doing a multivariate logistic regression analysis with a failed two step AABR screen as dependent and the above mentioned risk factors significant on univariate analysis as predictors, no factor emerged as significant. Even on repeating the multivariate analysis with all clinically relevant factors as predictors, none of the factors came as significant.
Discussion The results of the present study suggest that implementation of UNHS in tertiary care neonatal units, though feasible, is fraught with many challenges. The screening coverage in the index study was moderate, being 84 % as against the recommended bench mark of >95 % [6]. The primary reason was discharge of the infants prior to screening, as a single person was doing the screening with no back up staff to take over during her absence. Having a dedicated staff to perform the universal screening of infants, therefore, is the first important challenge to the establishment of any UNHS program in any set up. It is obvious from the present study that a single person for the purpose would not be adequate; and there is a need for additional staff to provide
Indian J Pediatr Table 2
Cost per test of automated auditory brainstem response [7]
Cost variables Basic costs Cost of building Cost of fixed assets Equipment cost Recurrent costs Cost related to salary Cost related to electricity Cost for consumables Total annual cost (A) = Basic costs + Recurrent costs Number of tests performed in a year (approx 170 tests per mo) (B) Cost per test (RUP) (A/B) Adjusted cost for the year of study based on inflation index of financial year 2011–12 (785)* Adjusted cost based on inflation index of financial year 2013–14 (939)**
Annual costs (in INR)
7155 1020 1,25,357 2,40,000 4994 601 3,79,127 170×12=2040 3,79,127÷2040=186 186×(785÷632)=231
186×(939÷632)=276
*The basic cost was calculated using year 2009–10, therefore was adjusted for the year of study using inflation index of 2011–12(186×785/632) ** The adjusted cost for present year has also been calculated (186×939/ 632); inflation index of year 2009–2010 was 632
cover during leave periods and possibly even on weekends/ holidays. This would be especially true for settings where the delivery rates are high. In such cases, multiple people would need to be employed if universal hearing screening is to be achieved. Though the option of training the nurses in doing the hearing screening has been suggested in some studies [8], it would need to be considered whether it would be possible and desirable to have them carve out time for hearing screening from that of clinical care. Another relevant model that has been suggested is a centralized screening with a single facility catering to all hospitals in a large city [9]. This would definitely bring down the cost significantly (as the number of tests done per year would increase substantially), but we will need to consider the loss to follow up that might happen post-discharge, especially for well infants, as it is likely that completing the screening might not be possible prior to discharge with such an arrangement. The second challenge would be to achieve a referral rate within the recommended benchmark of less than 4 % [6], which we could achieve using a protocol of two step AABR. It is to be noted in this context, that the “pass” and “refer” rates would depend on the protocol of hearing screening being used. The Joint Committee on Infant Hearing (JCIH) recommends separate protocols for neonatal intensive care units (NICUs) and well infant nurseries. While AABR is essential for the high risk infants (defined by JCIH as infants requiring more than 5 d of NICU stay), either ABR or OAEs may be used for well infant nurseries [6].
The authors extended the two step AABR screening protocol being used for the high risk infants even for the well babies in their unit, for two main reasons. First, it has been shown that even in non-NICU infants, a two-step AABR with a repeat screen prior to discharge minimizes the false positivity rates [8, 10]. Second, it was cost-effective for the authors as they already had an AABR instrument and it was desirable that the same be employed for universal screening than incur additional cost for OAE. However, the practical feasibility of employing any screening protocol in a unit needs to be considered. The authors were able to implement two step AABR as the average number of deliveries in their set up is approximately around 2500 per year. Other units which have a higher delivery rate might not find it practical, and use of OAEs may be considered to be more feasible, as the mean test time with OAE is lesser compared to AABR [11]. It is a matter of discretion and different recommended protocols may be used (OAEs alone or OAE followed by AABR). It would be however preferable that even for healthy neonates, if OAE is used for initial screening, a repeat screen for those who are “refer” be performed using either OAE or AABR to minimize the false positive rates [12, 13]. Further testing is required for other protocols using OAEs, including the time/postnatal age at which such screening should be done [14]. It is important to note with regard to the present results, that despite performing a two step AABR to minimize false positive results, of the 35 two step refers that were evaluated by conventional ABR, 30 had normal hearing. This suggests that the false positive rate, though it cannot be calculated exactly due to the lost to follow ups, was higher compared to the reported [15]. One plausible reason for this could be the initial screening of infants at less than 34 wk postmenstrual age [5], ear canal debris, and myogenic interference/ambient noises etc., which need to be further studied. The third but most important challenge was a significant loss to follow up at various stages of screening. It was authors’ policy to do the first AABR screen within 48–72 h of birth and repeat it for those who were “refer” within a week. This was an important reason for the lost to follow up rate as authors’ hospital is a referral centre and many parents living far could not come for follow up following discharge. When they started doing the re-screening prior to discharge, the loss to follow up to the second screen decreased (data not shown). This approach has also shown to be effective in reducing the false positive rates on UNHS earlier [16]. However, this strategy would not address the loss to follow up of those infants who would need a subsequent diagnostic workup with conventional ABR/audiologist in the ENT department. The average estimated cost of AABR per test in authors’ unit using the precise micro-costing method was INR 276 (for the year 2013–14). Since this cost has been calculated per test
Indian J Pediatr
assuming approx 170 tests per month, this would further decrease if the number of tests per month increases. This cost may be considered to be reasonable for newborn hearing screening for any individual centre, but of all the babies screened during the study period, only five infants were identified with hearing impairment, of which only two could be fitted with hearing aid. All the five infants were high risk infants (three being premature less than 32 wk, and two infants born at term; one with Pierre Robin syndrome with cleft palate and requiring tracheostomy; and second with congenital atresia of right ear canal with bilateral preauricular tags); who could also have been identified through a targeted/risk factor based screening. It is therefore important to reflect upon the costeffectiveness of UNHS in face of paucity of epidemiological data on the prevalence of hearing impairment among children attributable to congenital hearing loss, especially with regard to the risk groups. Looking at the results of the index study wherein ultimately only five of the huge 2700 infants screened, that too, all high risk, could finally be diagnosed with hearing impairment, UNHS does not seem to be cost-effective. However, one study in India has reported an incidence of hearing loss of 5.6 per 1000 infants screened at tertiary care units (10.75 per 1000 screened among high risk and 4.70 per 1000 screened among non-high risk infants), which is quite high [17]. Also, there is evidence to show that children identified through UNHS programs are referred, diagnosed, and treated significantly earlier, and have better receptive language scores than those identified with hearing loss through other ways (e.g., targeted/risk factor based screening). Whether this evidence would be applicable to the developing country settings such as ours where there are limited facilities available in terms of provision of discounted hearing aids and early intervention services, cannot be commented upon. Since there is paucity of data on cost effectiveness of UNHS compared to risk factor based screening at present to allow a comparison [18], it would be important to take an informed decision weighing the total cost and efforts at implementing UNHS on one hand, and the value of the possible difference it could make to the life of an infant, whatever small the number may be. The situation would however, be very different if there is a system wherein all the referrals on the initial two stage screening could be ensured a diagnostic evaluation and timely management. The limitations to the present study are that authors included all live births as eligible for the purpose of UNHS in their study, and did not exclude any baby based on congenital malformation, genetic/chromosomal abnormality or other factors. This however, is not likely to have affected the results, as the proportion of such babies was quite small, and the prevalence of hearing impairment was found to be low. Also, ideally the risk factors for hearing loss should be studied in patients with
confirmed hearing loss, the authors limited their approach to identify risk factors for a failed screen. This was done because the number of patients with confirmed hearing loss was too low in this study to do so. This also was an underestimate because there were a large number of losses to follow ups, and all those who failed the screen could not receive conventional ABR. The authors also could not get the infants with double refer examined by an ENT specialist before conventional ABR was performed.
Conclusions The important challenges of implementing UNHS at tertiary care neonatal units include moderate coverage with limited specialist staff and loss to follow up, with factor of costeffectiveness needing further exploration. Significant lost to follow up and non-linkage with appropriate rehabilitation services are likely to limit its utility in any set up and till the time such factors are taken care of, UNHS might not prove to be cost-effective compared to high risk based screening. Acknowledgments The authors would like to thank Ms. Ritu, technician in ENT for doing conventional ABR for the index infants. Contributions SG conceptualized and wrote manuscript, SS did AABR and follow up, CPY helped with statistical analysis, AT provided logistic support and also reviewed manuscript, MS, RA, AKD and VKP critically reviewed the manuscript. TS did the cost analysis and MJS provided study oversight and critically reviewed the manuscript. RA will act as guarantor for this paper. Conflict of Interest None. Source of Funding Delhi.
Indian Council of Medical Research (ICMR),
References 1. World Health Organization. Newborn and infant hearing screening: current issues and guiding principles for action. World Health Organization 2010. Available at www.who.int/blindness/ publications/Newborn_and_Infant_Hearing_Screening_Report.pdf. Accessed on 24/12/2014. 2. Jewel J, Varghese PV, Singh T, Varghese A. Newborn hearing screening—experience at a tertiary hospital in northwest India. Int J Otorhinolaryngol Head Neck Surg. 2013;2:211–4. 3. Universal hearing screening in newborn. Int J Basic Appl Med Sci. 2013;3:116–21. (http://www.cibtech.org/J-MEDICAL-SCIENCES/ P U B L I C A T I O N S / 2 0 1 3 / Vo l _ 3 _ N o _ 2 / J M S . . . 1 7 026...ANIL%20KUMAR...Universal%20hearing%20screening.pdf; last retrieved 10.01. 2015). Accessed 10 Jan 2015. 4. Augustine AM, Jana AK, Kuruvilla KA, Danda S, Lepcha A, Ebenezer J, et al. Universal neonatal hearing screening - experience in a tertiary care hospital in southern India. Indian Pediatr. 2013. pii: S097475591300554. [Epub ahead of print]
Indian J Pediatr 5. Coenraad S, Toll MS, Hoeve HL, Goedegebure A. Auditory brainstem response morphology and analysis in very preterm neonatal intensive care unit infants. Laryngoscope. 2011;121:2245–9. 6. American Academy of Pediatrics, Joint Committee on Infant Hearing. Year 2007 position statement: principles and guidelines for early hearing detection and intervention programs. Pediatrics. 2007;120:898–921. 7. Venkatnarayan K, Sankar MJ, Deorari A, Krishnan A, Paul VK. A micro-costing model of neonatal intensive care from a tertiary Indian unit: feasibility and implications for insurance. Indian Pediatr. 2014;51(3):215–7. 8. Clemens CJ, Davis SA. Minimizing false-positives in universal newborn hearing screening: a simple solution. Pediatrics. 2001;107:E29. 9. Paul AK. Early identification of hearing loss and centralized newborn hearing screening facility-the Cochin experience. Indian Pediatr. 2011;48:355–9. 10. Benito-Orejas JI, Ramírez B, Morais D, Almaraz A, FernándezCalvo JL. Comparison of two-step transient evoked otoacoustic emissions (TEOAE) and automated auditory brainstem response (AABR) for universal newborn hearing screening programs. Int J Pediatr Otorhinolaryngol. 2008;72:1193–201. 11. Meier S, Narabayashi O, Probst R, Schmuziger N. Comparison of currently available devices designed for newborn hearing screening using automated auditory brainstem and/or Otoacoustic emission measurements. Int J Pediatr Otorhinolaryngol. 2004;68:927–34.
12. Lin HC, Shu MT, Lee KS, Ho GM, Fu TY, Bruna S, et al. Comparison of hearing screening programs between one step with transient evoked otoacoustic emissions (TEOAE) and two steps with TEOAE and automated auditory brainstem response. Laryngoscope. 2005;115:1957–62. 13. Iwsaki S, Hayashi Y, Seki A, Nagura M, Hashimoto Y, Oshima G, et al. A model of two-stage newborn hearing screening with automated auditory brainstem response. Int J Pediatr Otorhinolaryngol. 2003;67:99–104. 14. Mathur NN, Dhawan R. An alternative strategy for universal infant hearing screening in tertiary hospitals with a high delivery rate, within a developing country, using transient evoked oto-acoustic emissions and brainstem evoked response audiometry. J Laryngol Otol. 2007;121:639–43. 15. Cebulla M, Shehata-Dieler W. ABR-based newborn hearing screening with MB11 BERAphone® using an optimized chirp for acoustical stimulation. Int J Pediatr Otorhinolaryngol. 2012;76:536–43. 16. Clemens CJ, Davis SA. Minimizing false-positives in universal newborn hearing screening: a simple solution. Pediatrics. 2001;107:E29. 17. Nagapoornima P, Ramesh A, Srilakshmi, Rao S, Patricia PL, Gore M, et al. Universal hearing screening. Indian J Pediatr. 2007;74:545–9. 18. Colgan S, Gold L, Wirth K, Ching T, Poulakis Z, Rickards F, et al. The cost-effectiveness of universal newborn screening for bilateral permanent congenital hearing impairment: systematic review. Acta Paediatr. 2012;12:171–80.
ORIGINAL ARTICLE
Challenges of Implementing Universal Newborn Hearing Screening at a Tertiary Care Centre from India Shuchita Gupta & Sandhya Sah & Tapas Som & Manju Saksena & Chander Prakash Yadav & M. Jeeva Sankar & Alok Thakar & Ramesh Agarwal & Ashok K. Deorari & Vinod K. Paul
Received: 7 June 2014 / Accepted: 1 January 2015 # Dr. K C Chaudhuri Foundation 2015
Abstract Objectives To report experience of implementing universal newborn hearing screening (UNHS) in a tertiary care neonatal unit, identify risk factors associated with failed two-step automated acoustic brainstem response (AABR) screen and evaluate cost of AABR. Methods This was a prospective study of UNHS outcomes of all live births with two step AABR using BERAphone MB11®. Outcome measures were screening coverage, refer, pass and lost to follow up rates and cost of AABR using micro-costing method. To identify risk factors for failed screening, authors performed multivariate logistic regression with failed two-step AABR screen as dependent variable and baseline risk factors significant on univariate analysis as predictors. Results Screening coverage was moderate (84 %), with 2265 of total 2700 eligible infants screened with initial AABR (mean gestation 37.2±2.3 wk; birth weight 2694±588 g; 305 received nursery care). A total of 273 of 2265 infants were “refer” on first screen. Second screen was done on 233, of which 58 were “refer”. Of these, 35 underwent conventional ABR, of which 5 were diagnosed to have hearing impairment. Only 2 could get hearing aid. Overall, a total of 2197 (81.4 %) infants passed, 496 (18.4 %; excluding 2 deaths) were lost to follow up at various stages, and S. Gupta : S. Sah : T. Som : M. Saksena : M. J. Sankar : R. Agarwal (*) : A. K. Deorari : V. K. Paul Newborn Health Knowledge Centre (NHKC), Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India e-mail: [email protected] C. P. Yadav Department of Biostatistics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India A. Thakar Department of ENT, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
5 (0.2 %) were diagnosed with hearing impairment, all of whom were high risk. Average cost of AABR was INR 276 per test. No factor emerged as significant on multivariate analysis. Conclusions UNHS is feasible to implement, but significant lost to follow up and non-linkage with appropriate rehabilitation services limit its utility. Cost effectiveness of UNHS compared to high risk based screening needs to be determined. Keywords Universal newborn hearing screening . Automated acoustic brainstem response
Introduction World Health Organization recognizes universal newborn hearing screening (UNHS) using either oto-acoustic emissions (OAEs) or automated auditory brainstem response (AABR) as a goal for all countries and communities with available rehabilitation services [1]. There is also a recent upsurge on the reporting of data on UNHS from many centers in India [2–4], thus implying the relative importance of this issue in recent time in most neonatal settings. However, there is limited data on the cost-effectiveness of UNHS using various approaches, especially at places where there is no system linking the screening and diagnostic assessments with appropriate rehabilitation services, which still remains a challenge in the best of set-ups. Therefore, for any neonatal unit, especially those currently performing high risk based hearing screening, it is important to understand the challenges and cost-effectiveness of implementing UNHS, before formulating a policy on the same. The present study was undertaken to objectively evaluate the feasibility and cost of implementing UNHS at a tertiary care neonatal unit, in order to inform decision on continuing
Indian J Pediatr
this program in the authors set up and implementation of the same across other such units in the country.
RUP is the predetermined estimated cost for providing a unit of healthcare service, from the hospital perspective.
Material and Methods The present data was collected prospectively as part of the UNHS initiated at the tertiary care neonatal unit of All India Institute of Medical Sciences (AIIMS), Delhi, India from May 2011 through June 2012. All live births during the study period were eligible for hearing screening. The main outcome measures were screening coverage by a single specialist staff, refer and loss to follow up rate, and the cost of AABR procedure using micro-costing method. The risk factors associated with a two step failed AABR screen were also assessed. All eligible infants were screened using a two step automated auditory brainstem response (AABR) by BERAphone MB11®. The first screen was done when the baby was stable, preferably between 24 to 48 h of birth, ensuring that preterm infants born at ≤32 wk of gestation were not screened before 34 wk of postmenstrual age [5]. Those infants who had a “refer” result on the first screen (either unilateral or bilateral) were re-screened within one week. The second screen was performed on both the ears even if the initial screen had only unilateral refer result, according to the guidelines of the Joint Committee on Infant Hearing (JCIH) [6]. Infants who were “refer” on the second screen (either unilateral or bilateral), were referred for a conventional ABR in the Department of ENT. All parents were counseled with regard to the importance and implications of the screening results, allaying undue anxiety while also stressing the need for follow up. AABR was performed using BERAphone MB11® in a quiet room devoid of any electromagnetic fields influence, during natural sleep. Acoustical CE-chirp stimuli were applied with high repetition rate of 93 clicks per second with an acoustic spectrum which is flat 750–5000 Hz. The skin around the patient’s ear was cleaned and small quantity (0.1–0.2 mL) of electrode-gel was applied at electrode sites. BERAphone headset was placed so that the respective electrodes were placed at their recommended positions on the forehead, mastoid and vertex. An impedance test was then performed to confirm correct position of the electrodes. Thereafter, if the indicator line reached the pass threshold within 3 min (180 s), test result was “pass”, otherwise; “refer”. A maximum of two attempts were allowed at each ear. A repeat AABR was performed within a week if the initial test result was “refer”. If the repeat AABR was also “refer”, then the baby was considered to have failed the two step AABR screening. Total cost for AABR was assessed based on micro costing method calculating the cost of the reference unit price (RUP).
Cost o f RUP ¼
ðBasic costs o f doing test þ incurred actual recurrent costs*Þ Total number o f tests during speci f ied period
*Basic costs include capital costs o f the building; annuitized equipment costs and costs o f f ixed assets; while incurred recurrent costs include costs incurred due to consumption o f human resources like salaries; various stores and electricity
The total annual cost of AABR was first calculated by adding the basic costs and then adding the incurred actual recurrent costs for doing all AABR tests during one year period. The basic costs consisted of the capital costs of the building, annuitized equipment costs and the costs of fixed assets. The incurred actual recurrent costs consisted of the costs of human resources (salaries), various stores and electricity [7]. The cost of RUP, i.e., cost of doing one AABR test was then estimated by dividing the total annual cost by the total number of tests during one year period (considering an average of approximately 170 tests per month), thereby providing the cost of a single test. Since the basic cost was calculated in the year 2009–10, the cost was adjusted for the year of study using inflation index of 2011–12. A systematic record of all babies being delivered at authors’ unit is maintained in an electronic database in MS Access which includes all important maternal, antenatal and perinatal details for any infant, along with details of hospital stay, major morbidities and treatment received. Weekly appraisal, quality checks and supervision of the database is done by an independent scientist. The results of the screen are also recorded and printed in the final discharge summary of the baby. All the baseline details, along with the major risk factors and details of hospital stay including NICU stay were imported from this database into STATA 11.0 (College Station, Texas, USA), checked for inaccuracies and inconsistencies and then analyzed. For risk factors, the authors did multivariate logistic regression with failed two-step AABR screen as dependent variable and baseline risk factors significant on univariate analysis as predictors. Analysis of risk factors was done using STATA 11.0. Results There were a total of 2765 live births during the study period, of which 2700 infants were discharged. Of the 2700 infants discharged, 431 were discharged before the first AABR could be done, 3 had pacemaker in situ and parents refused for screening in one. The initial AABR screen, therefore could be done in 2265 infants (Fig. 1). The screening coverage was 84 % among the infants discharged (2265/2700), while the refer rate following the
Indian J Pediatr Total live births, n=2765 Death, n=55; Refer to other unit, n=4; LAMA, n=6 Total discharged, n=2700
Discharged prior to test,
Initial AABR done, n=2265
n=431; Others, n=4
Pass, n=1992
Refer, n=273
Loss to follow up, n=39; Death, n=1
II AABR, n=233
Pass, n=175
Refer, n=58
Loss to follow up, n=22; Death, n=1
Conventional ABR, n=35
Pass, n=30
Refer, n=5
Fig. 1 Patient flow. AABR Automated Auditory Brainstem Response; LAMA Left against medical advice
second AABR screening was 2.1 % (58/2700), though it is limited by the fact that not all the infants “refer” on the initial AABR could be subjected to the second AABR screen. The distribution of major risk factors among infants who were screened with first AABR is shown in Table 1. The cost of AABR per test was INR 276 (Table 2) Table 1
Baseline details and risk factors in screened population
Variable
AABR done, n=2265 (%)
Gestation≤32 wk Mean ± SD Birth weight≤1500 g Mean ± SD Small for gestational age Multiple births Received nursery care>12 h Hypoxic ischemic encephalopathy Seizures Mechanical ventilation Intraventricular hemorrhage Down syndrome Systemic sepsis Hyperbilirubinemia requiring treatment
117 (5.2) 37.2±2.3 103 (4.5) 2694±588 134 (5.9) 150 (6.7) 305 (13.5) 20 (0.9) 8 (0.4) 44 (2.0) 8 (0.4) 4 (0.2) 51 (2.3) 282 (12.5)
On univariate analysis of various risk factors for a “refer” result on two step AABR, lower gestation, nursery care, systemic sepsis and mechanical ventilation were significant. On doing a multivariate logistic regression analysis with a failed two step AABR screen as dependent and the above mentioned risk factors significant on univariate analysis as predictors, no factor emerged as significant. Even on repeating the multivariate analysis with all clinically relevant factors as predictors, none of the factors came as significant.
Discussion The results of the present study suggest that implementation of UNHS in tertiary care neonatal units, though feasible, is fraught with many challenges. The screening coverage in the index study was moderate, being 84 % as against the recommended bench mark of >95 % [6]. The primary reason was discharge of the infants prior to screening, as a single person was doing the screening with no back up staff to take over during her absence. Having a dedicated staff to perform the universal screening of infants, therefore, is the first important challenge to the establishment of any UNHS program in any set up. It is obvious from the present study that a single person for the purpose would not be adequate; and there is a need for additional staff to provide
Indian J Pediatr Table 2
Cost per test of automated auditory brainstem response [7]
Cost variables Basic costs Cost of building Cost of fixed assets Equipment cost Recurrent costs Cost related to salary Cost related to electricity Cost for consumables Total annual cost (A) = Basic costs + Recurrent costs Number of tests performed in a year (approx 170 tests per mo) (B) Cost per test (RUP) (A/B) Adjusted cost for the year of study based on inflation index of financial year 2011–12 (785)* Adjusted cost based on inflation index of financial year 2013–14 (939)**
Annual costs (in INR)
7155 1020 1,25,357 2,40,000 4994 601 3,79,127 170×12=2040 3,79,127÷2040=186 186×(785÷632)=231
186×(939÷632)=276
*The basic cost was calculated using year 2009–10, therefore was adjusted for the year of study using inflation index of 2011–12(186×785/632) ** The adjusted cost for present year has also been calculated (186×939/ 632); inflation index of year 2009–2010 was 632
cover during leave periods and possibly even on weekends/ holidays. This would be especially true for settings where the delivery rates are high. In such cases, multiple people would need to be employed if universal hearing screening is to be achieved. Though the option of training the nurses in doing the hearing screening has been suggested in some studies [8], it would need to be considered whether it would be possible and desirable to have them carve out time for hearing screening from that of clinical care. Another relevant model that has been suggested is a centralized screening with a single facility catering to all hospitals in a large city [9]. This would definitely bring down the cost significantly (as the number of tests done per year would increase substantially), but we will need to consider the loss to follow up that might happen post-discharge, especially for well infants, as it is likely that completing the screening might not be possible prior to discharge with such an arrangement. The second challenge would be to achieve a referral rate within the recommended benchmark of less than 4 % [6], which we could achieve using a protocol of two step AABR. It is to be noted in this context, that the “pass” and “refer” rates would depend on the protocol of hearing screening being used. The Joint Committee on Infant Hearing (JCIH) recommends separate protocols for neonatal intensive care units (NICUs) and well infant nurseries. While AABR is essential for the high risk infants (defined by JCIH as infants requiring more than 5 d of NICU stay), either ABR or OAEs may be used for well infant nurseries [6].
The authors extended the two step AABR screening protocol being used for the high risk infants even for the well babies in their unit, for two main reasons. First, it has been shown that even in non-NICU infants, a two-step AABR with a repeat screen prior to discharge minimizes the false positivity rates [8, 10]. Second, it was cost-effective for the authors as they already had an AABR instrument and it was desirable that the same be employed for universal screening than incur additional cost for OAE. However, the practical feasibility of employing any screening protocol in a unit needs to be considered. The authors were able to implement two step AABR as the average number of deliveries in their set up is approximately around 2500 per year. Other units which have a higher delivery rate might not find it practical, and use of OAEs may be considered to be more feasible, as the mean test time with OAE is lesser compared to AABR [11]. It is a matter of discretion and different recommended protocols may be used (OAEs alone or OAE followed by AABR). It would be however preferable that even for healthy neonates, if OAE is used for initial screening, a repeat screen for those who are “refer” be performed using either OAE or AABR to minimize the false positive rates [12, 13]. Further testing is required for other protocols using OAEs, including the time/postnatal age at which such screening should be done [14]. It is important to note with regard to the present results, that despite performing a two step AABR to minimize false positive results, of the 35 two step refers that were evaluated by conventional ABR, 30 had normal hearing. This suggests that the false positive rate, though it cannot be calculated exactly due to the lost to follow ups, was higher compared to the reported [15]. One plausible reason for this could be the initial screening of infants at less than 34 wk postmenstrual age [5], ear canal debris, and myogenic interference/ambient noises etc., which need to be further studied. The third but most important challenge was a significant loss to follow up at various stages of screening. It was authors’ policy to do the first AABR screen within 48–72 h of birth and repeat it for those who were “refer” within a week. This was an important reason for the lost to follow up rate as authors’ hospital is a referral centre and many parents living far could not come for follow up following discharge. When they started doing the re-screening prior to discharge, the loss to follow up to the second screen decreased (data not shown). This approach has also shown to be effective in reducing the false positive rates on UNHS earlier [16]. However, this strategy would not address the loss to follow up of those infants who would need a subsequent diagnostic workup with conventional ABR/audiologist in the ENT department. The average estimated cost of AABR per test in authors’ unit using the precise micro-costing method was INR 276 (for the year 2013–14). Since this cost has been calculated per test
Indian J Pediatr
assuming approx 170 tests per month, this would further decrease if the number of tests per month increases. This cost may be considered to be reasonable for newborn hearing screening for any individual centre, but of all the babies screened during the study period, only five infants were identified with hearing impairment, of which only two could be fitted with hearing aid. All the five infants were high risk infants (three being premature less than 32 wk, and two infants born at term; one with Pierre Robin syndrome with cleft palate and requiring tracheostomy; and second with congenital atresia of right ear canal with bilateral preauricular tags); who could also have been identified through a targeted/risk factor based screening. It is therefore important to reflect upon the costeffectiveness of UNHS in face of paucity of epidemiological data on the prevalence of hearing impairment among children attributable to congenital hearing loss, especially with regard to the risk groups. Looking at the results of the index study wherein ultimately only five of the huge 2700 infants screened, that too, all high risk, could finally be diagnosed with hearing impairment, UNHS does not seem to be cost-effective. However, one study in India has reported an incidence of hearing loss of 5.6 per 1000 infants screened at tertiary care units (10.75 per 1000 screened among high risk and 4.70 per 1000 screened among non-high risk infants), which is quite high [17]. Also, there is evidence to show that children identified through UNHS programs are referred, diagnosed, and treated significantly earlier, and have better receptive language scores than those identified with hearing loss through other ways (e.g., targeted/risk factor based screening). Whether this evidence would be applicable to the developing country settings such as ours where there are limited facilities available in terms of provision of discounted hearing aids and early intervention services, cannot be commented upon. Since there is paucity of data on cost effectiveness of UNHS compared to risk factor based screening at present to allow a comparison [18], it would be important to take an informed decision weighing the total cost and efforts at implementing UNHS on one hand, and the value of the possible difference it could make to the life of an infant, whatever small the number may be. The situation would however, be very different if there is a system wherein all the referrals on the initial two stage screening could be ensured a diagnostic evaluation and timely management. The limitations to the present study are that authors included all live births as eligible for the purpose of UNHS in their study, and did not exclude any baby based on congenital malformation, genetic/chromosomal abnormality or other factors. This however, is not likely to have affected the results, as the proportion of such babies was quite small, and the prevalence of hearing impairment was found to be low. Also, ideally the risk factors for hearing loss should be studied in patients with
confirmed hearing loss, the authors limited their approach to identify risk factors for a failed screen. This was done because the number of patients with confirmed hearing loss was too low in this study to do so. This also was an underestimate because there were a large number of losses to follow ups, and all those who failed the screen could not receive conventional ABR. The authors also could not get the infants with double refer examined by an ENT specialist before conventional ABR was performed.
Conclusions The important challenges of implementing UNHS at tertiary care neonatal units include moderate coverage with limited specialist staff and loss to follow up, with factor of costeffectiveness needing further exploration. Significant lost to follow up and non-linkage with appropriate rehabilitation services are likely to limit its utility in any set up and till the time such factors are taken care of, UNHS might not prove to be cost-effective compared to high risk based screening. Acknowledgments The authors would like to thank Ms. Ritu, technician in ENT for doing conventional ABR for the index infants. Contributions SG conceptualized and wrote manuscript, SS did AABR and follow up, CPY helped with statistical analysis, AT provided logistic support and also reviewed manuscript, MS, RA, AKD and VKP critically reviewed the manuscript. TS did the cost analysis and MJS provided study oversight and critically reviewed the manuscript. RA will act as guarantor for this paper. Conflict of Interest None. Source of Funding Delhi.
Indian Council of Medical Research (ICMR),
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