APD as a Clinical Entity?
Vermiglio (2014) reports auditory processing disorder (APD) remains highly controversial, in part fueled by “multiple ambiguous descriptions of” of APD. Indeed, he reports referring to APD as a clinical entity is questionable with consideration of Sydenham and Guttentag’s (S&G) work in nosography (i.e., the systematic description of diseases). That is, to be a clinical entity, S&G state the clinical entity must have an unambiguous definition, must represent a homogenous group with a perceived limitation and the clinical entity must facilitate a diagnosis and intervention. Vermiglio notes the fact that APD may not be a clinical entity doesn’t deny that some people diagnosed with APD do have problems, the issue is that APD hasn’t been “unambiguously defined” and arguably does not represent a homogenous group and the diagnosis of APD may or may not facilitate intervention.
Vermiglio reviewed 22 behavioral tests from the Academy (2010) and ASHA (2005) APD test batteries to create a simple APD test battery matrix. To determine the diagnosis APD, a patient would need to demonstrate performance 2 or more standard deviations from the mean on two or more APD tests. Resultantly, there exist 462 subcategories (i.e., possible combinations) of APD. Vermiglio queries what if a given patient had taken multiple APD tests and performed poorly (more than 2 SD from the mean) on three, four or five APD tests. Would the intervention be the same as the person who performed poorly on only two?
Dillon and colleagues (2012) elaborated, as the number of tests increase, so too, does the opportunity to perform poorly due to accumulated statistical probability (and fatigue). Further, failing an APD test (or two) does not absolutely indicate the patient has a problem in real life. Specifically, failing an APD test (or two) does not absolutely indicate the patient has a problem, and if they don’t have a pragmatic problem, they are not limited, and therefore APD would not fit the definition of a clinical entity.
Vermiglio recommends the following questions as beneficial with regard to discovering the specific nature of the condition and the need for intervention:
- If APD is diagnosed, what is the definition of APD according to the person who made the diagnosis?
- Which tests were used?
- Were the APD tests “norm-referenced”?
- What criteria was used to diagnose APD?
- Which hearing-critical tasks is the patient using in daily life?
- Is the patient limited such that intervention is required?
- Is there a measureable speech recognition in noise deficit?
- Does the disorder meet the S&G criteria so as to be considered a clinical entity?
For More Information, References, and Recommendations
Dawes P. (2011) The SCAN-A in Testing for Auditory Processing Disorder in a Sample of British Adults. International Journal of Audiology 50:107–111.
Dillon H, Cameron S, Glyde H, Wilson W, Tomlin D. (2012) An Opinion on the Assessment of People Who May Have an Auditory Processing Disorder. Journal of the American Academy of Audiology 23:97–105.
Ferguson MA, Hall RL, Riley A, Moore DR. (2011) Communication, Listening, Cognitive, and Speech Perception Skills in Children With Auditory Processing Disorder (APD) or Specific Language Impairment (SLI). Journal of Speech, Language and Hearing Research54 (2):211–227.
Kreisman NV, John AB, Kreisman BM, Hall JW, Crandell CC. (2012) Psychosocial Status of Children with Auditory Processing Disorder. Journal of the American Academy of Audiology 23:222–233.
Sharma M, Purdy SC, Kelly AS. (2012) A Randomized Control Trial of Interventions in School-Aged Children with Auditory Processing Disorders. International Journal of Audiology 51:506–518.
Wilson WJ, Arnott W. (2013) Using Different Criteria to Diagnose Central Auditory Processing Disorder—How Big a Difference Does it Make? Journal of Speech, Language and Hearing Research 56:63–70.
Vermiglio AJ. (2014) On the Clinical Entity in Audiology: (Central) Auditory Processing and Speech Recognition in Noise Disorders. Journal of the American Academy of Audiology 25:4–917.