Some issues relevant to establishing a universal newborn hearing screening program

Tags: UNHS, OAE, ABR test, hearing loss, screening, testing, screening program, OAE test, births, screening test, congenital hearing loss, 40,000, referral rate, DPOAE test, DPOAE, program costs, unit costs, equipment costs, cost estimates, personnel costs, referral rates, precise estimates, screened, babies, screening tests, NICU, Michael P. Gorga, reimbursement, replacement costs, ABR test equipment costs, hearing screening test, emotional costs, administrative overhead, community hospitals, newborns, Universal Newborn Hearing Screening, otoacoustic emissions, otoacoustic emission, cost-efficient approach, health care providers
Content: J Am Acad Audiol 12 : 101-112 (2001) Some Issues Relevant to Establishing a Universal Newborn Hearing Screening Program Michael P. Gorga* Kimberly Preissler* Jeff Simmons* Lisa Walker'' Brenda Hoover"
Abstract This article describes some of the factors relevant to the establishment of a universal newborn hearing screening (UNHS) program . First, the difficulty in providing precise estimates of test sensitivity and specificity are reviewed . This section is followed by hypothetical estimates of overall programmatic costs, first for a fixed number of babies to be screened and then as a function of the number of babies to be screened in a year. Included in these estimates are the costs for equipment, disposables, personnel, and follow-up testing . These estimates are provided for three different screening protocols : auditory brainstem response (ABR) alone, otoacoustic emission (OAE) alone, and OAE followed by All only for those babies who failed the OAE screening . If follow-up costs are not included, it is less expensive to screen newborns with OAEs compared with the other two protocols . However, once follow-up testing is included as part of the program costs and there are at least 400 births per year, procedures in which OAEs are performed first, followed by an ABR on those infants who do not pass the OAE test, result in the lowest costs . Hospitals with as few as 400 births per year should expect per-baby costs not exceeding $30, regardless of which protocol is used . For all three protocols, the unit costs decrease as the number of babies screened increases . The final section describes data from a local UNHS program in which all infants are screened first with an OAE test, followed by an ABR test on infants not passing the OAE screening . Idiosyncratic features to this program are described, including the fact that all screening tests are performed by audiologists, who are paid on a part-time basis, adding cost to the program . Even under these circumstances, the unit cost is under $30 . These data lead us to conclude that all infants can be screened in a cost-effective manner . Key Words: Follow-up costs, program costs, universal newborn hearing screening Abbreviations : All = auditory brainstem response, DPOAE = distortion product otoacoustic emission, NICU = neonatal intensive care unit, OAE = otoacoustic emission, UNHS = universal newborn hearing screening
niversal newborn hearing screening U (UNHS) increasingly is becoming the standard of care throughout the United States . Whereas few hospitals or states were providing or requiring these services 10 years ago, today more than half of the states in the United States have passed legislation related to UNHS, *Boys Town National Research Hospital, Omaha, Nebraska Reprint requests : Michael P. Gorga, Boys Town National Research Hospital, 555 North 30th Street, Omaha, NE 68131
and several others have legislation pending . There are several competing factors driving the implementation of these programs, including the importance of early identification of Hearing Loss and the need to control program costs . In this article, we describe some of these issues in general terms, with particular attention directed toward factors that will influence the cost of such programs . In this regard, we will discuss the hypothetical costs related to the screening tool, protocol, and the number of babies screened each year. This general discussion will be followed by a description of a local program that has been in existence since June 1, 1998 .
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Several references exist that summarize the costs of UNHS programs (e .g., Johnson et al, 1993 ; Maxon et al, 1995 ; Mehl and Thomson, 1998 ; Kanne et al, 1999). The National Center for Hearing Assessment and Management provides additional references and an approach for estimating costs . (Further information about costs may be obtained by visiting its Web site, www.infanthearing.org .) In many cases, cost per baby screened is estimated. It would be expected that such estimates would be reliable, especially if they were based on large samples, which is almost always the case . Others have estimated the cost per baby identified with hearing loss (e .g ., Robinette and White, 1998 ; Kemper and Downs, 2000). Given the low prevalence of hearing loss, these estimates are based either on assumptions regarding the prevalence of hearing loss or on small numbers of infants with confirmed hearing loss . As a consequence, these estimates may vary more widely. In the present article, we will describe the cost for UNHS in relation to the design of the program and the screening protocol used in much the same way as others have estimated these costs . Specifically, the cost per baby screened will be evaluated because those estimates may be made with greater confidence . We will also show that the number of babies screened has a large impact on the per-baby costs of the screening program. We hope to demonstrate that the unit costs drop precipitously once the number of babies screened per year exceeds 400 to 500. The description of costs relative to the number of births may be of value in determining which screening approach will be most effective in relation to the size of the birthing facility. Developing an approach for estimating costs requires that some assumptions be made that might not apply in all situations. Certain programmatic costs may be generalized across centers, such as capital expenses (equipment), disposable costs (ear tips or cuffs, electrodes), and follow-up testing (for referrals) . Still, it is difficult to assign costs that would apply across all birthing facilities in the United States because other local factors will influence cost . The descriptions to follow include a general discussion of the costs of UNHS and a discussion specific to our program. The assumptions on which these estimates are based will be described; however, some assumptions may not be correct, and the description of our local program may be idiosyncratic to the conditions in which this program exists . As a result, the descriptions to follow may not generalize to
programs that differ from ours, either in their goals or protocols. GOALS OF UNHS t is widely accepted that the primary goal of UNHS is to identify infants with hearing loss in a cost-effective manner. This goal can be restated as one in which the aim is to achieve a high hit rate (or sensitivity), while the false-positive rate (one minus specificity) is kept low. There is a trade-offbetween hit and false-alarm rates for any test that does not perform perfectly, which, unfortunately, is the case for all audiometric tests, including hearing screening measures . It is also important to recognize that it is difficult to establish either the hit rate or the false-positive rate for any test used during UNHS . Hit rate is defined as the proportion of infants with hearing loss who are correctly identified as having hearing loss by the screening measure. It can be estimated only if all of the infants with hearing loss are known, which means that the auditory thresholds of all screened infants must be known. For practical and financial reasons, this is a near-impossible task because it would require independent assessment of all infants, passes and referrals. Norton et al (2000) describe one of the few studies that attempted to follow all newborns . Estimates of test sensitivity, based on those data, were viewed cautiously because the number of infants with hearing loss was small. Given the difficulty associated with performing an independent assessment of all newborns after the screening measure (including the need for data on a sufficient number of infants with hearing loss), it is widely assumed that passing the newborn hearing screening indicates that hearing is normal . Missing only a few newborns with hearing loss, however, can have a significant effect on test sensitivity because the prevalence of congenital hearing loss is so low. In spite of this problem, the known behavior of screening measures, both in older patients and in infants, suggests that it is likely the case that the majority of infants with hearing loss will fail the screening test and that those who pass will likely have no worse than a mild or moderate hearing loss (e .g., Gorga et al, 1999 ; Norton et al, 2000). Still, it is important to remember that there are problems associated with precise estimates of UNHS test sensitivity. Similarly, the false-positive rate cannot be known exactly unless all infants, passes and
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referrals, are evaluated with a measure that is independent of the screening measure . Errors in estimating the false-positive rate are much smaller than errors in estimates of the falsenegative rate because the vast majority of newborns will have normal hearing . Since approximately >_ 99 .7 percent of newborns have normal hearing, erroneously including in the denominator (for the purposes of calculating the false-positive rate) a child with hearing loss who passes a screening test will have little influence on estimates of specificity. In fact, it is widely recognized that, even for UNHS programs with referral rates of 2 percent or less, the majority of referrals will have normal hearing. This is equivalent to saying that a good estimate of the false-positive rate is the referral rate . Still, it is important to recognize that without independent verification of auditory status for all infants, an exact estimate of the false-positive rate is not possible . The goals of a UNHS program might be modified as a consequence of these issues . One reasonable approach might be to screen for hearing loss sufficient to result in immediate intervention ; these are losses for which the hit rate is more favorable . In routine clinical practice, a threshold exceeding 20 dB HL might be considered indicative of hearing loss . However, the precision with which pure-tone auditory thresholds can be estimated (especially at young ages), early sleeping patterns, the typical proximity of the infant to its primary care giver (resulting in higher sound pressure levels at the infant's ear), and practical issues related to feedback, monaural versus binaural amplification, and frequent earmold replacements make the need for immediate intervention (including the use of amplification) less obvious when "best" estimates suggest no more than a mild hearing loss . Thus, the goal might be to select screening criteria that are expected to identify infants with moderate or greater losses, knowing that some children with lesser losses might be missed, if such an approach could be achieved with a low referral rate . That is not to say that undetected mild hearing loss is without consequences . Certainly, mild hearing losses will have an impact on speech and language development . Further- more, hearing loss in these children, if missed at a newborn hearing screening, may go undetected for several years (Harrison and Roush, 1996) . It may be possible to select criteria that will identify all mild hearing losses, as well as losses of greater magnitude . The problem, however, is that the false alarm rate would be so high
and the associated costs so great that the program, in all likelihood, would not survive . Overall programmatic costs could be reduced if the number of babies requiring follow-up testing is reduced . By selecting criteria that perform well at identifying infants with moderate or greater hearing losses (e .g ., those losses exceeding 40 dB HL), the overall referral rate and, therefore, program costs can be reduced . Program credibility also might be affected by the referral rate . primary care physicians (pediatricians and family practitioners) know that congenital hearing loss is a rare disorder. If referral rates are high, then these primary care providers might lose confidence in the screening program, resulting in a low level of compliance for follow-up testing. Whether due to reduced overall program costs or greater acceptance by health care providers, it is likely that the extent to which UNHS is followed will increase if the referral rate is low . There are other costs associated with refer- rals that are not included in the estimates to follow. For example, parents may be required to travel some distance to obtain follow-up testing and/or may be forced to miss work . There may be costs associated with travel and absence from work, but these costs are difficult to estimate . In addition, there may be emotional costs to the family that has been told that their newborn did not pass his/her hearing screening test . Hopefully, this information is conveyed with appropriate sensitivity, including the notion that it is not uncommon for newborns with normal hearing to not meet test criteria very early in life . Indeed, it is likely that 90 percent of all referrals will have normal hearing, even for those programs with the lowest referral rates . This cost cannot be estimated (and, therefore, is not considered below) ; however, emotional stress highlights another important factor in keeping the referral rate low. COST ESTIMATES Cost Estimates for Equipment, Disposables, Personnel, and Follow-up Tests Several factors contribute to the cost of UNHS . Equipment costs represent the major capital expense. Currently, UNHS must rely on either an auditory brainstem response (ABR) test or an otoacoustic emission (OAE) test . Screening OAE tests fall into one of two categories : transient evoked OAEs (TEOAEs) or distortion
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product OAEs (DPOAEs) . Both ABR and OAE tests are available in either manual or automated versions . ABR test equipment costs approximately $17,000, whereas OAE equipment may be purchased for about $6500. The prices of specific pieces of equipment may vary ; these values are used only to provide a rough estimate of equipment costs. There may be other equipment costs, such as replacement of transducers and/or electrode boxes, but for the purposes of the illustrations to follow, it was assumed that there were no replacement costs for the duration of the screening. For automated ABR systems, disposable costs can be as high as $10 per baby (although ABR systems are available with lower disposable costs), whereas the disposable costs for OAE tests are approximately $1 per baby. Equipment costs, however, are only one part of the costs for a UNHS program. The overall referral rates for automated ABR are estimated to be around 2 percent, whereas the overall referral rates for OAE tests may be closer to 8 percent. Thus, babies can be screened less expensively with an OAE test, but added cost will be incurred because of the greater need for follow-up testing. Including the costs for follow-up tests in cost estimates may provide a more balanced assessment of overall programmatic costs, even though the screening program may be independent from the follow-up program in some settings and, thus, would not incur the follow-up costs. Equipment and disposable costs, with or without follow-up costs, can be combined with personnel costs in order to get a more complete estimate of at least some of the expenses that will be incurred by UNHS programs . These cost estimates are summarized in Table 1 . For the pur- poses of illustration, we consider the case in which 4000 babies need to be screened. Using an automated ABR approach, we would estimate the costs for UNHS to include equipment ($17,000)
and disposables ($40,000, $10/baby x 4000 babies). Personnel costs and the number of babies screened per hour are likely to vary across sites . Depending on local conditions, personnel costs may include benefits, as well as salary, both of which mayvary widely. However, assuming that four babies can be completely screened per hour (including documentation of results) and assuming salary and benefit costs of $20 per hour, personnel costs for screening 4000 babies would equal $20,000. Excluding database management, other indirect costs (all of which are difficult to estimate but will likely add to the overall program cost), and follow-up costs, these factors result in a cost of $77,000 to screen 4000 babies using an ABR test . This amounts to a per-baby screening cost of $19.25 . This may represent a slight overestimate of cost because it is possible that more than four babies can be screened per hour. If follow-up testing is to be included, then it was assumed that 2 percent of all babies did not pass the ABR test . This means that there would be 80 babies requiring additional testing after discharge . Unlike the screening program, where costs were estimated based on actual costs, here we use charges to estimate cost . This seems reasonable, since presumably the charges would reflect the fully loaded costs of perform- ing the procedures . The cost of follow-up testing was estimated at $200 per baby, which may not accurately represent these costs for any specific program . For example, many babies who return for follow-up testing may be retested with a less expensive screening measure . On the other hand, other follow-up tests on individual babies may be more expensive than $200 and, thus, would likely offset the lower costs associated with rescreening babies with a less expensive measure . For these reasons, we conclude that $200 per baby for follow-up testing is a reason- able estimate of the overall costs for these pro- cedures . Assuming a cost of $200 per follow-up
Table 1 Hypothetical Estimates of Costs for UNHS Programs Based Either on ABR Alone, OAE Alone, or Following a Protocol in Which OAEs Are Used First and ABRs Are Used Only forThose Babies Failing the OAE Screening
No. of Equipment Disposable Salary and Subtotal Cost/Baby Follow-up Subtotal CostlBaby
Test
Babies Costs
Costs
Benefits
#1
#1
Costs
#2
#2
ABR alone OAE alone OAE and ABR
4000 4000 4000
17,000 6500 23,500
40,000 4000 7200
20,000 20,000 21,600
77,000 30,500 52,300
19 .25 7 .63 13 .08
16,000 64,000 16,000
93,000 94,500 68,300
23 .25 23 .63 17 .08
Costs estimated first without including the costs for follow-up testing (subtotal #1 and cost/baby #1) and after including follow-up testing as part of the costs (subtotal #2 and cost/baby #2).
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test, this would result in an additional cost of $16,000 to the program, bringing the total to $93,000, or $23 .25 per baby screened . A similar approach for estimating costs can be used with OAE tests, as shown in Table 1 . OAE equipment ($6500 and disposable costs ($4000, $1/baby x 4000 babies) typically are lower than the associated costs for the ABR test. If we also assume that four babies can be screened each hour using an OAE test (this may be an underestimate of the number of babies that can be screened because there is no need to apply electrodes for OAE tests), salary and benefit costs to screen 4000 babies (at $20/hour) would amount to $20,000, just as they did for the ABR test . The cost for screening 4000 babies with only an OAE-based system would be approximately $30,500, or $7 .63 per baby. However, the referral rate is typically higher for OAE tests . With a referral rate of 8 percent, 320 babies (of the original 4000 babies) will need follow-up testing . Assuming that all 320 babies return and the cost of the follow-up test is $200 per baby, an additional $64,000 will be necessary. The total program cost, including follow-up testing, is $94,500, or $23 .63 per baby. Thus, once follow-up testing is added to the cost for the program, there is little difference between the cost for ABR- or OAEbased systems . A third alternative to either an ABR- or an OAE-based program is a combination of the two, the costs for which are also summarized in Table 1 . In such a protocol, equipment costs would require the purchase of two devices for $23,500 (ABR system for $17,000 and OAE system for $6500) . All 4000 babies would be screened with an OAE test first (resulting in a disposable cost of $4000) . Eight percent of the babies are not expected to pass the OAE test and, thus, would require an ABR test prior to hospital discharge . The disposable costs incurred for doing an ABR test on these 320 babies would equal $3200 . Salary and benefit costs for performing the OAE screening on all babies would be $20,000 (see above) . Additional personnel costs would be incurred in order to perform ABR tests on the 320 babies failing the OAE screen . Using the same assumptions that were used to estimate ABR costs alone (four babies per hour, person- nel costs of $20/hour), an additional $1600 in personnel costs would be needed . Using the ABR to screen these babies prior to hospital discharge results in a referral rate of 2 percent, the same referral rate that was assumed for protocols in which only ABRs were performed . If the costs for both pieces of equipment, disposables, and per-
sonnel are summed, the overall cost for screening 4000 babies in this protocol would be $52,300, or $13 .08 per baby. Thus, this protocol is cheaper than the protocol based solely on ABR tests but more expensive than the one based solely on OAEs . However, protocols based solely on OAE tests result in higher referral rates . In a protocol in which OAEs are used first and ABRs are used only for infants not passing the OAE test, 80 babies would require follow-up testing (2% of the total sample of 4000 would be expected to fail the ABR screen) . Assuming that all 80 of these babies return for follow-up testing, the cost for the follow-up tests would be $16,000 (80 babies x $200/baby) . Including the costs for follow-up testing, the total program cost for a system in which OAEs and ABRs are used is $68,300, or $17 .08 per baby screened. The capital cost of additional equipment is more than offset by the reduced costs that can be achieved by having lower disposable costs and lower referral rates . When follow-up costs are included, the overall cost is the least if an OAE test is performed first and an ABR test is reserved only for those infants failing the OAE screening test . Such an approach follows a protocol that is virtually identical to the one recommended by the National Institutes of Health (NIH) in its 1993 consensus statement . Cost Estimates Related to the Number of Babies Screened In the scenarios above, it was assumed that equipment would be replaced for every 4000 babies screened . It would not matter if those babies were screened over a 6-month period or over 5 years . In reality, this type of equipment typically remains functional for as long as 5 years . Program costs would differ substantially if one considers the lifespan of equipment relative to the number of babies screened in cost calculations . The hypothetical costs for UNHS will be described next for the case in which it is assumed that the equipment will be replaced after 5 years, regardless of the number of babies screened over that period . Table 2 shows cost estimates when the ABR is used as the screening tool . Costs are shown for cases in which the number of babies screened per year varies from 25 to 8000 . For the purposes of this illustration, it was assumed that all babies could be screened with one piece of equipment . There may be circumstances, however, in which more than one piece of equipment is required, especially for large birthing facilities .
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Table 2 Effects of the Number of Babies Screened on the Hypothetical Costs for a UNHS Program Based on ABR Tests
Births
Births in
per Year 5 Years
25 50 75 100 200 300 400 500 1000 2000 4000 8000
125 250 375 500 1000 1500 2000 2500 5000 10,000 20,000 40,000
Equipment Disposable Salary and Subtotal Cost/Baby Follow-up Subtotal CostlBaby
Costs
Costs
Benefits
#1
#1
Costs
#2
#2
17,000 17,000 17,000 17,000 17,000 17,000 17,000 17,000 17,000 17,000 17,000 17,000
1250 2500 3750 5000 10,000 15,000 20,000 25,000 50,000 100,000 200,000 400,000
625 1250 1875 2500 5000 7500 10,000 12,500 25,000 50,000 100,000 200,000
18,875 20,750 22,625 24,500 32,000 39,500 47,000 54,500 92,000 167,000 317,000 617,000
151 .00 83 .00 60 .33 49 .00 32 .00 26 .33 23 .50 21 .80 18 .40 16 .70 15 .85 15 .43
500 1000 1500 2000 4000 6000 8000 10,000 20,000 40,000 80,000 160,000
19,375 21,750 24,125 26,500 36,000 45,500 55,000 64,500 112,000 207,000 397,000 777,000
155 .00 87 .00 64 .33 53.00 36 .00 30 .33 27 .50 25 .80 22 .40 20 .70 19 .85 19 .45
Even under those circumstances, that cost is divided among a large number of infants. For example, if a birthing facility with 8000 births per year required three complete sets of OAE and ABR equipment, the additional cost per baby over 5 years would be $1 .18 ($47,000 additional equipment cost divided by 40,000 babies). With between 25 and 8000 births per year, over a 5-year period, the total number of babies screened with a single piece of equipment varies from 125 to 40,000 . Overall cost increases but the cost per baby screened decreases as the number of babies screened increases. Hospitals with a large number of births per year, therefore, are in a position to deliver this service at a lower unit cost, compared with hospitals in which there are few births per year. If keeping per-baby costs below $30.00 represents a reasonable tar-
get, then the effect is most striking between hospitals with small numbers of births per year (200 or less if follow-up is not included ; 300 or less if follow-up costs are included) compared with the other birthing numbers shown in this table. This suggests that small community hospitals with few births per year will be faced with higher per-baby screening costs than hospitals with 400 births per year or more . Table 3 shows the same estimates for a screening program based solely on OAE tests. As with ABR-based programs, overall costs increase but per-baby costs decrease as the number of babies screened increases. In this case, however, there is less difference in per-baby costs for small versus large birthing hospitals. Assuming that a per-baby screening cost of $30.00 or less is acceptable, then hospitals with as few as 75
Table 3 Effects of the Number of Babies Screened on the Hypothetical Costs for a UNHS Program Based on OAE Tests
Births
Births in
per Year 5 Years
25 50 75 100 200 300 400 500 1000 2000 4000 8000
125 250 375 500 1000 1500 2000 2500 5000 10,000 20,000 40,000
Equipment Disposable Salary and Subtotal Cost/Baby Follow-up Subtotal Cost/Baby
Costs
Costs
Benefits
#1
#1
Costs
#2
#2
6500 6500 6500 6500 6500 6500 6500 6500 6500 6500 6500 6500
125 250 375 500 1000 1500 2000 2500 5000 10,000 20,000 40,000
625 1250 1875 2500 5000 7500 10,000 12,500 25,000 50,000 100,000 200,000
7250 8000 8750 9500 12,500 15,500 18,500 21,500 36,500 66,500 126,500 246,500
58 .00 32 .00 23 .33 19 .00 12 .50 10 .33 9 .25 8 .60 7 .30 6 .65 6 .33 6 .16
2000 4000 6000 8000 16,000 24,000 32,000 40,000 80,000 160,000 320,000 640,000
9250 12,000 14,750 17,500 28,500 39,500 50,500 61,500 116,500 226,500 446,500 886,500
74 .00 48 .00 39 .33 35 .00 28 .50 26 .33 25 .25 24 .60 23 .30 22 .65 22 .33 22 .16
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births per year (not including follow-up) or as few as 200 births per year (including follow-up) can achieve this cost . The final illustration estimates cost when OAEs are used first and ABR tests are performed only on those infants not passing the OAE screening test . This approach would be the most expensive for the small hospital in which few births occur each year because the capital expenses (equipment costs) are divided over fewer babies . Over a 5-year period, a hospital with only 25 births per year would incur a per-baby cost of $199 .20, the highest of the three scenarios presented in this article . The "acceptable" per-baby cost of $30 .00 or less is achieved for hospitals with 300 or more births/year regardless of whether follow-up testing is included, although the lowest costs are incurred when follow-up testing is not included . Although screening programs based solely on OAE measurements achieve the lowest costs when follow-up testing is excluded, the differences between per-baby costs for it and for the protocol that includes both OAEs and ABRs decrease as the number of births increases . If follow-up costs are considered a part of the overall program cost, then the protocol that includes OAEs and ABRs has the lowest cost for hospitals having at least 400 births per year. That cost advantage increases as the number of births per year increases above 400 . All three scenarios, shown in Tables 2 to 4, indicate that one of the most important Factors Affecting the unit costs of UNHS is the number of babies screened . Large birthing facilities will incur the smallest per-baby costs for screening . To the extent that correct assumptions were made when estimating these costs, it would
appear that hospitals with 400 or more births per year will be more cost effective using a protocol in which OAEs are performed first and ABRs are reserved for infants not passing the OAE tests, especially when follow-up costs are considered . Cost problems will exist for hospitals having few births per year . It may be necessary for small birthing facilities to accept the higher referral rates associated with OAE screening programs in order to keep the per-baby screening costs sufficiently low. This compromise is reasonable so long as follow-up services are available to evaluate these referrals . Another solution to the problem of low numbers of births is for small hospitals to form consortiums in which equipment and staff are shared . Such arrangements will reduce some of the costs, but the added travel that will be required in going to different facilities will offset some of the gains accrued by forming consortiums . There may be alternative approaches that might help to make UNHS cost effective in smaller birthing facilities . Equipment continues to advance to the point that hearing screenings can be performed simply and without much training . If existing nursing staff can perform these tests as part of their regular duties, then personnel costs would be reduced or eliminated . If larger, regional facilities can provide follow-up testing for those infants not passing the screening test, then the follow-up costs to small birthing facilities would be reduced as well . There are, however, other costs associated with UNHS programs that were not included in the scenarios developed above. Overall program management will result in supervisory costs, although once these programs are running, the
Table 4 Effects of the Number of Babies Screened on the Hypothetical Costs for a UNHS Program Based on OAE Tests First and ABR Tests Only on Those Infants Failing to Meet Criteria on the OAE Test
Births
Births in
per Year 5 Years
25 50 75 100 200 300 400 500 1000 2000 4000 8000
125 250 375 500 1000 1500 2000 2500 5000 10 .000 20,000 40,000
Equipment Disposable Salary and Subtotal CostlBaby Follow-up Subtotal Cost/Baby
Costs
Costs
Benefits
#1
#1
Costs
#2
#2
23,500 23,500 23,500 23,500 23,500 23,500 23,500 23,500 23,500 23,500 23,500 23,500
225 450 675 900 1800 2700 3600 4500 9000 18,000 36,000 72,000
675 1350 2025 2700 5400 8100 10,800 13,500 27,000 54,000 108,000 216,000
24,400 25,300 26,200 27,100 30,700 34,300 37,900 41,500 59,500 95,500 167,500 311,500
195 .20 101 .20 69 .87 54 .20 30 .70 22 .87 18 .95 16 .60 11 .90 9 .55 8 .38 7 .79
500 1000 1500 2000 4000 6000 8000 10,000 20,000 40,000 80,000 160,000
24,900 26,300 27,700 29,100 34,700 40,300 45,900 51,500 79,500 135,500 247,500 471,500
199 .20 105 .20 73 .87 58 .20 34 .70 26 .87 22 .95 20 .60 15 .90 13 .55 12 .38 11 .79
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Journal of the American Academy of Audiology/Volume 12, Number 2, February 2001
need for supervision will likely be reduced. Database management and clerical and secretarial assistance for scheduling follow-up tests have costs associated with them. These costs, however, are difficult to estimate unless the conditions of specific programs are known. Furthermore, their costs may be offset by some of the factors, reviewed above, that might result in lower costs than those described in the above scenarios. OUR LOCAL UNHS PROGRAM W e have conducted a UNHS program at a local birthing hospital since June 1, 1998 . As of May 31, 2000, 4460 infants have been tested through this program. This represents 97 .5 percent of all births at the hospital ; a small number of infants (110 babies, or 2.5%) were either missed or their parents refused the screening. This program was designed following the recommendations made in the NIH (1993) consensus statement. Specifically, all infants are screened first with a DPOAE test, followed by an ABR test on every infant who does not pass the DPOAE test in both ears . All tests are performed prior to hospital discharge. With few exceptions, well babies were tested on the first or second day of life . For well babies delivered by cesarean section, tests were often postponed until the third or fourth day of life . Graduates from the neonatal intensive care unit (NICU) were tested close to the time of hospital discharge . DPOAE Test Criteria DPOAEs were measured with a screening device (Bio-Logic, AuDX). These responses were measured at f2's of 2, 3, 4, and 6 kHz. Primary frequency ratio was held constant at 1.22. The levels of fl and f2 were set to 65 and 55 dB SPL, respectively. In order to pass the DPOAE test, a minimum signal-to-noise ratio (SNR) of 6 dB had to be achieved, in addition to minimum DPOAE levels, varying slightly depending on frequency. These criteria were selected based on previous experience in older patients, where it was shown that these criteria would result in high hit rates for moderate or greater hearing losses, with a false-positive rate of less than 2 percent (Gorga et al, 1999). If an infant met these criteria, no further testing was performed. This protocol, however, would miss any infant with hearing loss above the level of the outer hair cells, such as in the case of auditory neuropathy.
Implicit in this approach is the notion that the screening program is designed to detect only peripheral hearing loss and is insensitive to other forms of hearing loss . ABR Test Criteria For the ABR test, a manual system was used (Bio-Logic, Navigator) in which the operator evaluated the ABR waveform to determine if a response was present. Every infant who did not pass the DPOAE test received an ABR test . For this test, an electrode was placed on the high forehead and was referenced to an electrode placed at the ipsilateral mastoid, with an electrode placed on the contralateral mastoid serving as ground. Responses were filtered (100-3000 Hz) and amplified (100 k) prior to averaging. A 100-,sec click presented at 30 dB nHL (0 dB nHL = 35 dB PSPL) served as the screening stimulus, which was presented via an insert earphone (Etymotic, ER-3A) . A pass occurred if the operator observed a response to this stimulus . Infants not producing an ABR were referred, as outpatients, for further testing. No additional testing was performed prior to hospital discharge. Using this manual ABR procedure required that the operator have some experience in evaluating ABRs, which added to personnel costs. However, our disposable costs were less than half of those incurred with automated systems. It is important to recognize that producing a click-evoked ABR does not necessarily mean that hearing is normal . An ear with high-frequency hearing loss restricted to frequencies at and above 3 kHz might produce an ABR in response to a click. Still, such criteria were necessary in order to balance competing needs of holding the referral rate as low as possible while identifying infants with sufficient hearing loss to result in immediate intervention . It may also be important to remember that both OAEs and ABRs are less sensitive to low-frequency hearing loss . OAEs show poorer performance for frequencies at and below 1500 Hz, primarily as a consequence of high levels of noise surrounding these frequencies. ABRs are less sensitive to hearing loss at lower frequencies, presumably because responses from fibers innervating these regions of the cochlea are less synchronized, making it more difficult to distinguish them from the noise background . These limitations for both OAEs and ABRs may be of less relative significance because hearing loss affecting higher frequencies is more common .
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Specific Conditions for This UNHS Program As a consequence of local hospital policy, all newborn hearing screening tests have to be performed between the hours of 5:30 am and 7:30 am daily. This restriction affects the pass rates on DPOAE tests, as will be seen subsequently. In addition, all tests are performed by clinical audiologists, who are paid on a part-time basis and must perform the screenings during the above time window, which adds to the personnel costs of the program. Whereas $20 per hour was used to estimate salary and benefits for the scenarios presented above, the personnel costs for this program are $30 per hour. Detailed estimates of the costs for this program will be presented in a subsequent section. Program Performance In the well-baby nursery, the initial DPOAE test was passed by 62 percent of all newborns . In the NICU, the initial DPOAE pass rate was 94 percent . The reason for the low initial pass rate among well babies is a direct consequence of the idiosyncratic nature of the program. As stated above, all tests had to be performed between 5 :30 am and 7 :30 am . If all babies going home on any given day had already been tested and time remained, babies born only several hours earlier were tested in an effort to use our time efficiently. The failure rate among these babies (less than a day of age) was high (see, for example, Kok et al, 1992) . Higher failure rates may be a consequence of the status of the external and middle ears early in life (Chang et al, 1993) . However, these infants often remained in the hospital for another day and were, therefore, tested during the same hours (5 :30-7 :30 am) of the following day. An additional 31 percent of the well babies passed this second DPOAE test, resulting in an overall well-baby pass rate of 93 percent . Some babies in the NICU also remained available for another day after the initial DPOAE screening test . In the NICU, an additional 3 percent passed the second DPOAE test . Thus, 97 percent of all NICU graduates passed the DPOAE screening test prior to discharge as well . As a result, 93 percent of all babies (well babies and NICU graduates combined) passed the DPOAE test prior to hospital discharge . The remaining 7 percent of babies not passing the DPOAE test were immediately screened with an ABR test . An additional 5 percent of well
babies passed this screening test, whereas an additional 1 percent of babies from the NICU passed the ABR test . To date, the overall referral rate for this program is approximately 1.7 percent. It is important to recall that both the ABR and DPOAE tests are performed prior to hospital discharge. Although exact estimates remain elusive, the expected prevalence of congenital hearing losses that would result in immediate intervention is approximately 1 to 3 per 1000 births . Thus, even with a referral rate of just under 2 percent, only 1 in about 7 to 10 of the referred babies would be expected to have hearing loss (assuming that all infants with hearing loss failed the hearing screening) . Only four infants with hearing loss have been identified thus far from this program. However, not all referrals return to our facility for follow-up testing. Primary care physicians refer their patients to other providers in the community ; as a result, we cannot estimate prevalence of hearing loss in this group. Given the low incidence of congenital hearing loss, prevalence estimates would not be considered reliable even if all referrals returned to us for follow-up testing. As UNHS becomes more widely adopted and as states initiate tracking systems, better estimates of prevalence may result. However, problems associated with follow-up have been noted by many centers engaged in UNHS, and it is unclear whether a database tracking system will result in greater compliance for further testing . Local Program Costs Based on experience with this admittedly idiosyncratic program (which follows the NIH 1993 guideline), it is possible to estimate more completely the local costs of UNHS . These costs are summarized in Table 5 . A number of facts and some assumptions went into the development of this table . There are approximately 2200 births per year at this hospital . These statistics have held for approximately 5 years, and we expect those numbers to continue indefinitely. Averaged across a year, this means that there were approximately six babies to be tested every day. Equipment costs were $23,500 . This includes the ABR and the DPOAE systems . These costs were incurred in the first year of program operation . It is assumed that the equipment will have a usable lifespan of 5 years . Thus, equipment costs appear in the first year but not in the subsequent 4 years . The calculation of disposable costs includes $1 per baby for all initial DPOAE
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Journal of the American Academy of Audiology/Volume 12, Number 2, February 2001
Table 5 Cost of UNHS for Our Local Program, Estimated over 5 Years
No . of Equipment Disposable Salary and Subtotal Cost/Baby Follow-up Subtotal Cost/Baby
Year Babies
Costs
Costs
Benefits
#1
#1
Costs
#2
#2
1
2200
2
2200
3
2200
4
2200
5
2200
Total 11,000
23500 23,500
3828 3828 3828 3828 3828 19,140
21,900 21,900 21,900 21,900 21,900 109,500
49,228 25,728 25,728 25,728 25,728 152,140
22 .38 13 .83
8800 8800 8800 8800 8800 44,000
58,028 34,528 34,528 34,528 34,528 196,140
26 .38 17 .83
Follow-up costs are based on the assumption that the referral rate = 2% (currently, it is under 1 .7%) and that all infants referred from the UNHS program return for follow-up testing, which is not the case,
tests ($2200/year) plus $1 per baby on those infants who were tested twice with the DPOAE test prior to discharge ($858, based on 39% of 2200, or 858 babies, requiring a second DPOAE test). Of the total sample, 154 babies required an ABR test, incurring additional disposable costs, which, for our system, are estimated at $770 ($5/baby). In total, the disposable costs for each year equal $3828. Personnel costs are $21,900 based on an hourly rate of $30.00, multiplied by the need to test for 2 hours per day and 365 days per year. This rate must be paid regardless of the number of babies tested on any given day, making it unnecessary to estimate personnel costs relative to the number of babies tested per hour. Although all referrals from the UNHS program do not return to us for follow-up testing, we assumed that they did in order to estimate follow-up costs. We estimate that approximately 44 infants each year will be referred for follow-up at a per-baby cost of $200 . The cost of follow-up testing, therefore, is estimated at $8800 per year. This estimate of follow-up costs is high for two reasons. First (as stated above), not all referrals return to us for follow-up testing. Second, every baby who does return to us receives a screening test first, which costs $57 per baby. The majority of the infants returning for follow-up testing pass this screening test . As a result, they do not require more expensive diagnostic procedures . After the first year of operation, the cost excluding follow-up testing was $49,228, or $22.38 per baby screened . The overall cost increased to $58,028, or a cost per baby of $26.38, when follow-up testing is included . After 5 years, the expected cost without follow-up testing will be $152,140 ($13 .83 per baby screened). If follow-up testing is included, the program costs increase to $196,140, which translates into a cost per baby of $17.83 .
DISCUSSION protocol in which all infants are screened Awith a DPOAE test, followed by an ABR screening only for those infants who do not pass the DPOAE test, is an efficient and cost-effective means for screening for hearing loss . This approach results in overall referral rates under 2 percent. A recent summary of the New York State UNHS demonstration project also reported the lowest referral rates for programs in which a two-stage protocol was followed (Gravel et al, 2000). In fact, the referral rates reported in the NewYork study were virtually identical to those observed by us . This two-stage protocol also resulted in the lowest overall costs, at least for hospitals in which there are at least 400 births per year. Lower costs for the two-stage protocol were especially evident when the costs for followup testing were included in these estimates. In addition to a need to control costs, we also were interested in focusing on hearing losses for which intervention would be obvious and immediate. We would not argue that 25 or 30 dB HL thresholds are normal . Indeed, it could be argued that thresholds of 15 or 20 dB HL are not normal, especially in an infant, who has yet to be exposed to environmental factors that might result in threshold elevation. However, there are several factors making it less urgent to find infants with these slight threshold elevations . First, there is the precision with which threshold can be estimated. Even among cooperative patients, behavioral threshold estimates are accurate to within about 5 dB, using typical clinical procedures . Behavioral estimates in children are less reliable, especially early in life . For infants less than 6 months of age developmentally, ABR thresholds should be used to provide estimates of auditory thresholds (which would be needed for prescriptive hearing-aid fit-
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Issues in UNHS/Gorga et al
ting procedures). These thresholds also have measurement errors associated with them . A one-to-one correspondence between electro- physiologic and behavioral thresholds (assuming that behavioral thresholds are accurately measured) would not be expected . Even if auditory thresholds could be estimated precisely (which is not the case), the form of intervention in a newborn with mild hearing loss is not obvious. For example, should an infant with bilateral "thresholds" of 30 dB HL be fit with one or two hearing AIDS? Fitting the child with one aid might represent a conservative choice until more is learned about the hearing loss, but it reduces or eliminates the advantage of listening with two ears . There are practical issues that make intervention less urgent as well when mild hearing loss exists . Typically, the primary care giver is in close proximity to the infant, especially early in life . The nature of that physical relationship will provide a higher level of input to the child's ear, thus compensating partially for the hearing loss . In addition, the signal-to-noise ratio at the child's ear will be favorable during its earliest months of life . Finally, infant ears grow rapidly early in life (regardless of whether hearing loss of any magnitude is present) ; in infants with hearing loss, this means that frequent earmold replacements are required . When one considers the uncertainty associated with threshold estimates in the newborn and the proximity of the infant to the primary care giver, along with practical issues related to monaural or binaural amplification and earmold replacement, it is difficult to justify the added costs in over-referrals that would be incurred if criteria were selected that attempted to identify all infants with mild hearing loss . Another important factor in UNHS relates to the number of babies that will be screened by the program . The cost estimates for our program are based on providing screening services to 2200 babies per year. There are many hospitals in the United States where the birth rates are much higher. Their per-baby screening costs would be lower than ours, using the same assumptions as were used to calculate our costs . On the other hand, hospitals with fewer births will have greater unit costs . For example, Nebraska is a geographically large state, but its population is only 1 .6 million . In the entire state, there are approximately 23,000 births each year. The majority of those births occur in the Omaha and Lincoln catchment areas . However, a significant number of births occur in smaller communities scattered throughout the
state . There are many community hospitals with 100 or fewer births per year. The overall costs of UNHS will be less for these small hospitals, but the per-baby costs may be exces- sively high . It will be necessary for these smaller birthing facilities to provide UNHS differently than larger facilities in order to control overall program costs . For these reasons, it is difficult to see how estimates of costs for UNHS, developed in one state or at one hospital, can be applied to other states or hospitals, where the protocol, the number of babies, and the goals might differ. Having said that, it is clear to us that with 2200 births per year, UNHS can be provided efficiently and at a relatively low cost, given our overall program goals . The cost estimates for screening newborns are not excessive, however, even for hospitals in which only 300 to 400 babies are born each year. This is true whether one uses ABR alone, OAE alone, or a combination of the two tests . Individual sites will have to determine whether it is cost effective to screen all newborns when the per-baby costs are $30 or less ; however, it would appear that the per-baby cost will be within this range for screening newborns in many circumstances . The most cost-efficient approach when follow-up costs are considered and for hospitals with 400 births per year appears to be one in which OAEs are performed first, and ABRs are performed only on those infants not passing the OAE test . This approach has a positive influence on the cost by reducing both the disposable costs and the follow-up costs . Greater confidence in the screening program from other health care providers should also be achieved because the referral rate is acceptably low. Two additional factors should be considered when costs for UNHS are being evaluated . There is some administrative overhead associated with providing UNHS, including overall supervision of the program, as well as hospital overhead above equipment, disposable, and personnel costs related to performing the tests . Administrative overhead was not considered in the present estimates of cost but must be considered if the intent is to provide a cost-effective service . It is also important to remember that estimates of cost (including administrative overhead) may be meaningful only if providing the service is accompanied by appropriate reimbursement . By appropriate reimbursement, we mean reimbursement sufficient to cover the fully loaded costs of the program . This view should be considered when setting fee schedules in light of the fact that reimbursements, under
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the best of circumstances, typically are a percentage of charges. Although it would appear that UNHS can be provided for reasonable cost under most circumstances, the extent to which UNHS becomes a reality will likely be related to the level of reimbursement health care providers receive for the service relative to the costs they incur for providing those services . REFERENCES Chang KW, Vohr BR, Norton SJ, Lekas MD . (1993) . External and middle ear status related to evoked otoacoustic emission in neonates . Arch Otolaryngol Head Neck Surg 119:276-283 . Gorga MP, Neely ST, Dorn PA . (1999). DPOAE test performance for a priori criteria and for multifrequency audiometric standards . Ear Hear 20 :345-362 . Gravel J, Berg A, Bradley M, Cacace A, Campbell D, Dalzell L, DeCristofaro J, Greenberg E, Gross S, Orlando M, Pinheiro J, Regan J, Spivak L, Stevens R, Prieve B. (2000) . New York State Universal Newborn Hearing Screening Demonstration Project: effects of screening protocol on inpatient outcome measures . Ear Hear 21 :131-140 . Harrison M, Roush J. (1996) . Age of suspicion, identification, and intervention for infants and young children with hearing loss : a national study. Ear Hear 17 :55-62 . Johnson JL, Mauk GW Takekawa KM, Simon PR, Sia CCJ, Blackwell PM. (1993). Implementing a statewide
system of services for infants and toddlers with hearing disabilities . Semin Hear 14 :105-119 . Kanne TJ, Schaefer L, Perkins JA . (1999) . Potential pitfalls of initiating a newborn hearing screening program. Arch Otolaryngol Head Neck Surg 125 :28-32. KemperAR, Downs SM. (2000). Acost-effectiveness analysis of newborn hearing screening strategies . Arch Pediatr Adolesc Med 154:484-488 . Kok MR, van Zanten GA, BrocaarMP. (1992) . Growth of evoked otoacoustic emissions during the first days postpartum . A preliminary report. Audiology 31 :140-149 . Maxon AB, White KR, Behrens TR, Vohr BR . (1995) . Referral rates and cost efficiency in a universal newborn hearing screening program using transient evoked otoacoustic emissions (TEOAE). JAm Acad Audiol 6:271-277 . Mehl AL, Thomson V (1998) . Newborn hearing screening : the great omission. Pediatrics 101 :1-6 . National Institutes of Health . (1993) . Early identification of hearing impairment in infants and young children. NIH Consens Statement 1-24 . Norton SJ, Gorga MP, Widen JE, Folsom RC, Sininger Y, Cone-Wesson B, Vohr BR, Mascher K, Fletcher KA. (2000) . Identification of neonatal hearing impairment : evaluation of TEOAE, DPOAE, and ABR test performance. Ear Hear 21 :508-528 . Robinette MS, White KR . (1998) . The state of newborn hearing screening. In : Bess FH, ed. Children with Hearing Impairment : Contemporary 7}ends . Nashville, TN : Vanderbilt Bill Wilkerson Center Press, 45-67.

File: some-issues-relevant-to-establishing-a-universal-newborn-hearing.pdf
Title: Some Issues Relevant to Establishing a Universal Newborn Hearing Screening Program
Author: Journal of the American Academy of Audiology
Published: Tue May 11 11:11:56 2004
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