Objective: To evaluate the newborn transient evoked otoacoustic emission (TEOAE) hearing screening tests of infants later diagnosed with the sudden infant death syndrome (SIDS).
Study design: In a case-controlled study, the newborn TEOAE hearing screens of 31 infants who subsequently died of SIDS were retrospectively compared to those of 31 newborn infants that survived the first year of life. SIDS cases were individually matched to surviving controls based on gender, term versus preterm age and NICU versus well baby nursery.
Results: The TEOAE screens of SIDS infants demonstrated significantly decreased signal to noise ratios at 2000, 3000, and 4000 Hz (p <>
Conclusion: Newborns at risk for SIDS are currently indistinguishable from other newborns and are only identified following a later fatal event. A unilateral difference in cochlear function is a unique finding that may offer the opportunity to identify infants at risk of SIDS during the early postnatal period with a simple non invasive hearing screen test. The ability to implement preventative measures well in advance of a potential critical incident would be an important breakthrough.
10 comments:
This is really interesting. Roger Thornton (UK) has always maintained that low OAE strength in the first hours was a result of birth trauma. Not seeing the evidence, I have been happy to assume it was middle ear and debris related, but perhaps not.
I do have a few statistical and data concerns about the paper. First is the use of signal to noise ratio as the dependent variable. Its not a good physiological measure because it is compounded with an independent variable - noise. SNR is good for determining if there IS a signal above the noise, but not for establishing the strength of that signal. So I think the authors have missed out on presenting the data in terms of OAE strength (i.e., amplitude). Of course, all things being equal- SNR will correlate well with OAE strength - so this omission doesn't undermine the entire paper - it just weakens the statistics.
Another thing that weakens the stats in my opinion is the decision to use only 31 controls to match the number of SIDS case. This is too small. The variance in the SIDS cant be reduced - but the variance in the reference population could be - by increasing this number to a few hundred. Id also want to know that the half octave noise levels in the compared groups were not significantly different from the SIDS cases.
Is a larger study underway? I hope so. I know several people have said they are interested - but I haven't heard of a project yet
The main finding is that SIDS infants had lower OAE signal-to-noise ratios
(SNR) than a matched control group. SNR has limitations as a measure of inner ear function, since it is logically possible that the SIDS babies had identical OAEs and (for some reason) higher noise floors, compared to the control group. Because the data presented to not permit a conclusion about the source of the difference, many interpretations of the outcome are possible, none of which is supported unambiguously. Another point that should be emphasized is that the range of individual differences in OAE amplitude in normal infants is large; the standard deviation of SNR is at least 5-10 dB. This variability in the population precludes using OAE amplitude to make any estimate of the risk for SIDS for a single baby.
The paper concludes that infants who are prone to SIDS have lower OAE signal-to-noise ratios (SNR)in the right ear (but not the left) during newborn hearing screening, than infants who are not prone to SIDS. The implication is that newborn hearing screening results may be a way to identify infants who are at risk for SIDS.
Although the hypothesis deserves further testing based on this preliminary result, it really needs more (and better)research before being accepted as fact.For example, 1) SNR is not a good dependent measure because it combines amplitude of the OAE with noise -- the data should be analyzed based on amplitude. 2) The rationale for why the differences occur in the right ear, but not the left is not convincing--another way to look at this is that it is a failure to replicate, even within this small sample. 3) More information about how the controls were selected for each case needs to be given....were they randomly selected from the available population? It would have been much better to have had at least 3-4 randomly selected controls (after stratification on key variables) for each case.
The article proposes an interesting hypothesis, but the conclusions are certainly a stretch. The use of signal-to-noise ratios is problematic and leads to questions about the study's integrity. While the current study is flawed, further research is warranted with a larger number of subjects and appropriately selected controls.
This is a very interesting article, but I felt that many of the statistics and composition of the study were weak. More research on this same concept would be very interesting to see.
The first thing that struck me was that all of the SIDS cases were from Rhode Island and the article didn't mention where the control cases were from. The study would have gained a lot of strength by increasing the spread to several states drawing in a more divers demographic and significantly increasing the sample size.
The second thing that got my attention was how the controls were selected. It was surprising that the selection of matched controls didn't appear to be random. A lot of information on the selection process of the controls was missing such as if they were all chosen from Rhode Island as well.
While this is an interesting article I have some basic concerns. Use of SNR is confounded by the presence of noise, which influences OAE outcomes. Noise is related to probe fit, environmental factors and baby state. Since this is a retrospective study these factors could not be taken into account. Additionally, there is a significant amount of inter-subject variability, that is not addressed in this article.
Before any credence is given to the findings of this study, I would like to see similar studies done that use randomized selection rather than the weaker statistical measure of historical controls. It would be essential to include a more widespread demographic group as well. There may be something in the soil of Rhode Island that causes changes in the SNR as well as respiratory difficulty. Lastly, if there truly is a correlation between TEOAE’s and SIDS then the next steps would need to be taken in order to figure out what to do with this knowledge using the proper ethical undertones. Would you tell parents that there child is in a high infant mortality population? Or would vital sign monitoring equipment be used as a preventative tool? This paper definitely raises eyebrows along with unanswered questions about the data.
Although I found this article intriguing I would not say that the conclusions were supported by the data. I agree with the comments posted above and don't know if I have much to add. This article is a great starting point for further research in using TEOAE as a determinate for SIDS. As stated above by many of my collegues, there needs to be more done.
The researchers suppose a lot of information to be true to reach their desired conclusions. Only a small population was observed, and not all demographic information was known. In the discussion section the researchers describe how a perinatal insult could occur, however a lot of assumptions are made based on previous research as to what possibly occurs.
The researchers make the point that this could help determine which infants are susceptible to SIDS, but I would like to see how they would use this information since the pathogenesis of SIDS remains unknown. How do they propose to save these infants, especially since their research lacks so much.
Although this is an interesting subject, the conclusion of this study does lack some statistical power with an N=31, and a paucity of demographic data. I would like to see a larger study performed. I think it would be nice if OAEs could be a marker for susceptibility of SIDS, but I think it needs to be studied further and the authors have not provided a strong conclusion
I would like to know a little bit more about their claim that inner ear insults can contribute to respiratory failure. It seems to be a major foundation for the study and I feel it would strengthen the paper if that was explained in more detail. Also, 31 infants is a rather small number. The results are very compelling but they would be even more so had they used more infants, possibly from multiple states. My third concern was regarding their explanation for unilateral findings. Their only cited source for the placental blood moving to the right ear was a color atlas of anatomy. More research to back that up would add strength to that explanation. Overall, I felt the article was very interesting and I will definitely look out for further research in theis area.
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