A transition in audiology is underway. Audiologists are moving beyond the current allied health status and sole interest in the ear to an inter-professional status and awareness of ear health as a component of whole-body health. This professional transition has been decades in the making, picking up momentum with the expanding knowledge of comorbidities between many chronic diseases and sensorineural hearing loss (SNHL).
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hearing loss, chronic diseases
Figure 1: Clinical decision-making flowchart for possible co-management of audiology patients with comorbid chronic conditions.
One in two adults has a chronic medical condition and one in four adults has multiple chronic conditions (CDC, Aug. 2018 http://bit.ly/2pKfbkc; CDC, Sept. 2018 http://bit.ly/2pKBwy2). These conditions persist for 12 months or more, have a slow progression, rarely resolve spontaneously, and are normally not curable by medical intervention. They are the leading causes of death and disability in the United States and the leading driver of American health care costs (approaching $3 trillion per year; CMS, 2016 https://go.cms.gov/2pM2Agk). Treatment of patients with chronic diseases accounts for over 70 percent of the dollars spent on U.S. health care and over 90 percent of Medicare expenses (CDC, Aug. 2018 http://bit.ly/2pKESkC).
This article outlines a multi-step process for audiologists to determine the existence and clinical significance of comorbidities and the actions they can take to contribute toward improving patient outcomes in a holistic manner.
STEP 1: EVALUATION
The first step in the process is to conduct the audiological evaluation following normal, best-practice protocols. Following the evaluation, the audiologist should determine the presence of hearing loss and, if it is present, identify if the test results attribute the loss of auditory function to sensorineural impairment.
Detecting cochlear loss is critical to this plan of action. The inner ear has characteristics that make it susceptible to the pathophysiology associated with many chronic diseases. The inner ear is supplied by an end artery, has no collateral circulation, and is highly vulnerable to vascular disease and ischemia. Also, the inner ear has fragile structures with high metabolic demand and is sensitive to functional degradation that results from hypoxia, toxicity, and small vessel disease. By virtue of training and profession, the audiologist is best qualified to assess and monitor the function of the inner ear. With this knowledge of cochlear status, the audiologist can assist with detecting and monitoring some chronic diseases as well as providing strategies for improved patient management.
STEP 2: CASE HISTORY
The second step is to review the patient's case history for the presence of chronic diseases or conditions. There is no definitive list of chronic diseases; lists prepared by different organizations have slight variations. The Centers for Disease Control and Prevention (CDC) list includes heart disease and high blood pressure, cancer (breast, cervical, colorectal, gynecological, skin), chronic lung disease, stroke, Alzheimer's disease, arthritis, diabetes and prediabetes, chronic kidney disease, epilepsy, lupus, obesity, and tooth decay (CDC, Aug. 2018; CDC, Sept. 2018). At a minimum, a method of identification of these illnesses should be included in the case history form for audiology patients.
Chronic diseases have multiple and sometimes overlapping pathophysiology. Vascular diseases include macrovascular disease that involves the large blood vessels and microvascular disease of the small blood vessels (small vessel disease or SVD). Macrovascular disease can cause restriction of blood flow, resulting in an ischemic event such as a myocardial infarction (MI or heart attack) or cerebrovascular accident (CVA or stroke). Microvascular disease is associated with angina (chest pain) and dementia (progressive brain injury and disease). Neurological disorders involve the central and peripheral nervous systems. These disorders may be secondary to vascular disease, such as stroke, and may be degenerative, e.g., Alzheimer's. In some cases, the cause is unknown, such as with seizure disorder epilepsy. Metabolic syndrome is associated with increased blood pressure, elevated blood sugar, and abnormal cholesterol levels, and can result in diabetes mellitus. The major contributors to metabolic syndrome are lifestyle factors of in-activity (lack of exercise), nutrition (poor diet), alcohol (excessive), and tobacco use. Fortunately, changes in these areas can lessen the impact of metabolic syndrome and diabetes.
STEP 3: HEARING LOSS AND COMORBIDITY
For the purposes of this article, SNHL will be treated as a chronic condition, as it typically has a slow progression (except for ischemic events) and long duration. The third step is to determine if both chronic hearing loss and another chronic condition are present. If so, comorbidity, the simultaneous presence of two or more chronic conditions or diseases, is present in the patient. Comorbidity is associated with worse health outcomes, more complex clinical management, and increased health care costs (Ann Fam Med. 2009 Jul-Aug;7(4):357).
The presence of comorbidity can imply an interaction between the two illnesses that can affect the course and prognosis of both. Fortunately, the metric called the odds ratio (OR) can be used to identify if chronic conditions have an underlying relationship that is more than a chance occurrence. An OR of 1 indicates there is no increased prevalence of one condition in the presence of the other condition, whereas an OR greater than 1 indicates increased occurrence of one condition when the other condition is present. For example, an OR of 2 indicates that the probability of a patient having condition B is doubled when condition A is present.
STEP 4: ODDS RATIO
The fourth step is to determine if there are increased ORs of the chronic disease (from the case history) and SNHL (from the audiometric evaluation) because higher OR values may indicate an associated pathology. With regard to SNHL, elevated ORs have been found for vascular diseases (heart disease, high blood pressure, stroke, chronic kidney disease); neurological disorders (Alzheimer's disease, the most common form of dementia); and the metabolic syndrome of diabetes.
STEP 5: CLINICIAN'S SELF-EVALUATION
Once a comorbidity with elevated ORs is identified, the audiologist must conduct a self-evaluation and determine her or his readiness to attempt some form of patient co-management of the patient's comorbidity. The audiologist must answer this question: “Do I want to try and be involved in information sharing with other health care providers to help improve the patient outcome?”
The answer to this question is an important decision on how audiologists will practice their profession. The objective of the Doctor of Audiology (AuD) movement was to improve practitioner education such that audiologists would engage in peer-to-peer interactions with other medical professionals. Following this educational step, the legislative step is underway in the form of the Audiology Patient Choice Act (APCA) that would grant Medicare recipients direct access to audiologists for diagnosis, treatment, and rehabilitation of hearing disorders. With direct access comes the opportunity and responsibility to transition from providing isolated care for auditory and vestibular disorders to providing necessary awareness about the interactions between hearing and balance disorders and whole-body health, wellness, and illness.
STEP 6: TEAM MANAGEMENT
If the answers to steps three, four, and five are all yes, then the audiologist can initiate step six: Communicate toward possible team management of comorbid chronic conditions. These communications are typically with the patient's primary care provider, who may be a physician (MD), physician assistant (PA), or nurse practitioner (NP). At first glance, this team-based approach may seem asymmetric because of the differences in the scope of practice of the professionals involved. MDs, PAs, and NPs have medical diagnostic rights accompanied by privileges of prescribing medications, whereas the audiologist does not.
VALUE OF AUDIOLOGISTS
However, audiologists can add unique value to the team through multiple contributions. First, as previously noted, the audiologist is the sole member of the team who can comprehensively assess inner ear functions. This is important because the presence of certain types of hearing loss can be a predictor of chronic disease conditions. For example, low-frequency SNHL may be an early indicator of vascular disease involving heart health. Not only is the presence of SNHL important in a comorbidity case, significant changes in SNHL may occur along with changes in other chronic conditions such as kidney disease.
Second, audiologists are the only members of the team prepared to provide treatment to ameliorate the effects of SNHL. Such treatment should result in improved communication with the other health care professionals, thereby reducing the occurrence of medical errors and increasing patient compliance to treatment plans. This is important to MDs, PAs, and NPs because failures in clinical communication are considered a leading cause of medical errors, and patient hearing loss is a factor in miscommunications in the health care setting (Hearing Journal. 2017;70[9]:6 http://bit.ly/2pNCiKI).
Third, audiologists can better inform other health care professionals of the presence of the hearing disorder and expectations from (untreated and/or treated) patients in auditory exchanges. Audiologists can provide guidance on how to improve information transfer with patients during in-office visits and hospitalizations. They can also alert health professionals to the other effects of hearing loss, such as misevaluating a patient's misunderstanding as cognitive decline when it was actually due to impaired hearing.
It is an exciting time to be an audiologist as the profession transitions from allied health support to frontline patient care. With this change, many patients can have their initial visit for hearing health care with audiologists. As such, audiologists must be aware of whole-body health and the interactions between chronic diseases and SNHL, and prepared to contribute in new ways to inter-professional practice—a long-term objective of the AuD movement. The path to the future goes beyond providing comprehensive audiological evaluations; it includes evaluating case histories and looking for chronic conditions that are comorbid with SNHL and have increased OR. The audiologist's decision to co-manage comorbid conditions by collaborating with other health care professionals can significantly improve patient outcomes.
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