Optimizing Clinical Interpretation of Distortion Product Otoacoustic Emissions in Infants

Objectives: The purpose of this study was to analyze distortion product otoacoustic emission (DPOAE) level and signal to noise ratio in a group of infants from birth to 4 months of age to optimize prediction of hearing status. DPOAEs from infants with normal hearing (NH) and hearing loss (HL) were used to predict the presence of conductive HL (CHL), sensorineural HL (SNHL), and mixed HL (MHL). Wideband ambient absorbance was also measured and compared among the HL types. Design: This is a prospective, longitudinal study of 279 infants with verified NH and HL, including conductive, sensorineural, and mixed types that were enrolled from a well-baby nursery and two neonatal intensive care units in Cincinnati, Ohio. At approximately 1 month of age, DPOAEs (1–8 kHz), wideband absorbance (0.25–8 kHz), and air and bone conduction diagnostic tone burst auditory brainstem response (0.5–4 kHz) thresholds were measured. Hearing status was verified at approximately 9 months of age with visual reinforcement audiometry (0.5–4 kHz). Auditory brainstem response air conduction thresholds were used to assign infants to an NH or HL group, and the efficacy of DPOAE data to classify ears as NH or HL was analyzed using receiver operating characteristic (ROC) curves. Two summary statistics of the ROC curve were calculated: the area under the ROC curve and the point of symmetry on the curve at which the sensitivity and specificity were equal. DPOAE level and signal to noise ratio cutoff values were defined at each frequency as the symmetry point on their respective ROC curve, and DPOAE results were combined across frequency in a multifrequency analysis to predict the presence of HL. Results: Single-frequency test performance of DPOAEs was best at mid to high frequencies (3–8 kHz) with intermediate performance at 1.5 and 2 kHz and chance performance at 1 kHz. Infants with a conductive component to their HL (CHL and MHL combined) displayed significantly lower ambient absorbance values than the NH group. No differences in ambient absorbance were found between the NH and SNHL groups. Multifrequency analysis resulted in the best prediction of HL for the SNHL/MHL group with poorer sensitivity values when infants with CHL were included. Conclusions: Clinical interpretation of DPOAEs in infants can be improved by using age-appropriate normative ranges and optimized cutoff values. DPOAE interpretation is most predictive at higher F2 test frequencies in young infants (2–8 kHz) due to poor test performance at 1 to 1.5 kHz. Multifrequency rules can be used to improve sensitivity while balancing specificity. Last, a sensitive middle ear measure such as wideband absorbance should be included in the test battery to assess possibility of a conductive component to the HL. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and text of this article on the journal's Web site (www.ear-hearing.com). ACKNOWLEDGEMENTS: The efforts of Alaaelddin Elsayed, MD, AuD, Leigh Shaid, AuD, several research coordinators, and the families who participated is gratefully acknowledged. The authors are appreciative of the anonymous reviewers who substantially improved the manuscript. C. M. B. performed experiments, analyzed data, and co-wrote the article. L. L. H. designed and performed experiments, co-wrote the article, and provided interpretive analysis and critical revision to the article. D. H. K. and M. P. F. designed experiments, and provided interpretative analysis and critical revision to article. D. K. B helped design and perform experiments and provided interpretative analysis and critical revision to article. A. M. assisted in enrollment and data analysis as part of her AuD capstone. D. F. F. designed experiments, and provided interpretative analysis and critical revision to article. L. L. provided statistical analysis and critical revision to the article. All authors discussed the results and implications and commented on the manuscript at all stages.. Portions of this study were presented as poster presentations at the American Academy of Audiology; March 2014; Orlando, FL; and at the American Auditory Society; March 2016; Scottsdale, AZ. This research was supported by the National Institute of Deafness and other Communication Disorders of the National Institutes of Health under Award Number R01 DC010202 and an American Recovery and Reinvestment Act of 2009 supplement (DC010202-01S1). Co-author D. H. K. is involved in commercializing devices to assess middle ear function in infants. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Health. The content of this article does not represent the views of the Department of Veterans Affairs or of the United States Government. D. K. B. collected data while employed at Cincinnati Children's Hospital Medical Center. Address for correspondence: Chelsea M. Blankenship, Communication Sciences Research Center, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA. E-mail: chelsea.blankenship@cchmc.org Received January 27, 2017; accepted January 3, 2018. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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