Cochlear implants have been performed in patients with bilateral moderate to profound hearing loss since the 1970s. The general populations’ lifespan is increasing, with 8.9 million people expected to be 85 years of age or older by 2030 and 18 million people to be 85 years of age or older by 2050. In addition to the aging population, the criteria for implantation are expanding. Therefore, the age at which cochlear implants are placed has increased and patients are living longer with their cochlear implants.
Cochlear implant audiologic outcomes in the aging population (>70 years old) compared with their younger counterparts (<70 years old) have been studied in the literature and have shown that the older population tend to have equal improvements in speech discrimination compared with the younger cohorts (1–4). However, the impact that comorbidities in the older group on performance or complication rate has not been as clearly elucidated. The goal of this study is to compare audiologic outcomes (preoperative and postoperative hearing in noise test [HINT] and/or AZBio Sentence) and complication rates for the over 70-year-old population versus those in the less than 70-year-old population. Secondary outcomes measured include the comorbidities in each group as well as any impact on multiple or specific comorbidities may have on complication rates and outcome.
MATERIALS AND METHODS
A retrospective chart review was performed at the Michigan Ear Institute after the approval of the institutional review board for human research at St John's Hospital and Providence Park Hospital. One hundred and one patients who received a cochlear implant through for bilateral severe to profound hearing loss from 2010 to 2015 were included in this study.
Audiologic tests include the HINT and AZBio sentence testing with “best aided” ability performed by audiologists (5,6). The HINT and/or AZBio testing was completed at 3 months, 6 months, and 12 months postimplant. The last test result (12-month test) was used as the “postimplant” test for purposes of statistical analysis. Additional data collected included the patient's age, sex, side of implant, active comorbidities, and clearance from a physician before the cochlear implantation procedure.
One hundred and one total patients were identified and included in the review. Fifty-one of these patients were age 18 to 69 years (Group 1) at time of implantation. Fifty of these patients were age 70 to 89 years (Group 2) at the time of implantation.
All patients met criteria for cochlear implantation with bilateral severe to profound hearing loss. All patients had preimplant and postimplant HINT and/or AZBio testing completed. The patient's preimplant and postimplant HINT and/or AZBio testing, age, comorbidities, medical clearance, and complications were reviewed and documented.
Fifty one patients under the age of 70 (Group 1) were reviewed. Their mean age was 54 (range, 18–69) at time of implantation. Average length of follow up for Group 1 was 25.2 months (range, 12.2–34.7). Fifty patients over the age of 70 (Group 2) were reviewed and their mean age was 54.5 (70–89) at time of implantation (Table 1). The average length of follow up for Group 2 was 39.2 months (19.0–47.3). In Group 1, 35 of 50 (70%) patients underwent medical clearance, whereas, all patients in Group 2 underwent medical clearance by their primary care physician or their cardiologist.
In Group 1, 18 of the patients had their right ear implanted, 15 had their left ear implanted, and 18 elected to have bilateral implants. In Group 2, 20 of the patients had their right ear implanted, 26 had their left ear implanted, and 4 elected to have bilateral implants.
Patients in Group 1 scored an average of 18% (range, 0–55%, standard deviation [SD] = 19) on HINT testing preimplant and an average of 82% (range, 52–100%, SD = 16) on HINT testing postimplant. AZBio testing preoperatively was 16% (range, 0–50%, SD = 19) and 67% (range, 32–99%, SD = 28) postoperatively (Table 2). The patients in Group 2 scored an average of 14.6% (range, 0–45%, SD = 14) on HINT testing preimplant and an average of 77.8% (range, 18–100%, SD = 21) on HINT testing postimplant. Preimplant AZBio mean was 17.9% (range, 0–56%, SD = 16) and postimplant mean was 72.1% (range, 28–100%, SD = 22) (Table 2). Audiologic outcomes comparing the mean preimplant and postimplant HINT (p = 0.65, p = 0.19), mean preimplant and postimplant AZBio (p = 0.48, p = 0.22) between Groups 1 and 2 were analyzed utilizing the paired t test and revealed no statistically significant difference between Groups 1 and 2 in any category using a p = 0.05 as significant. (See, Table 2).
The comorbidities in the over 70-year-old group included hypertension (HTN) 76% (38/50), coronary artery disease (CAD) 34% (17/50), Diabetes Mellitus type 2 (DM2) 24% (12/50), atrial fibrillation 6% (3/50), chronic obstructive pulmonary disorder (COPD) 4% (2/50), aortic valve stenosis 4% (2/50), pulmonary fibrosis 4% (2/50), aortic and cerebral aneurysm 2% each (1/50) (Fig. 1). Comorbidities in the under 70-year-old group included HTN 46% (46/51), DM2 24% (8/15), obstructive sleep apnea (OSA) 18% (9/51), hypothyroidism 16% (3/50), CAD 12% (6/51), COPD, Arnold Chiari, and chronic kidney disease (CKD) accounted each for 2% (1/50) (Table 3). The frequency of the specific comorbidities between Groups 1 and 2 was compared. Group 2 had an increased frequency of comorbidities compared with Group 1, but this did not reach statistical significance using the paired t test (Table 3).
The complication rate in Group 1 was 6/50 (12%). Five (10%) included a minor cellulitis treated with antibiotics with resolution, and one patient (2%) developed a wound infection that required parenteral antibiotics and hospitalization. The complication rate in Group 2 was 27%. Five (10%) mild cellulitis, 3/51 (6%) with infection requiring antibiotics, 3/51 (6%) hematoma, and 3/51 (6%) with wound dehiscence (Table 4).
In each group, the most common comorbidities (HTN, DM2, hypothyroidism, OSA) were analyzed individually to determine whether there was a significant difference between complication rates that may be attributable to a specific comorbidity. For example, patients with hypertension were isolated and the complication rate in that patient group was analyzed. This was then repeated for each of the common comorbidities in each group. Utilizing analysis of variance test, no statistically significant difference could be shown between each comorbidity category (Fig. 2). Likewise for Group 2, the complication rates for each of the most common comorbidities (HTN, CAD, DM2, OSA) were analyzed without any significant difference between categories (Fig. 3). The complication rates per comorbidity in Groups 1 and 2 were then compared using the t test to determine significance. No significance was noted between groups in any specific comorbidity (Table 3).
Cochlear implantation in patients with severe to profound bilateral hearing loss has long been recognized as a reliable and safe means of hearing rehabilitation in both adults and the pediatric population. Some studies have shown that the elderly population obtains less benefit from cochlear implantation than the younger cohorts (7). Conversely, several studies have shown that the elderly population have similar outcomes in quality of life and similar audiological outcomes to a younger cohort (8–12). This study's results agree with previous studies that the elderly population can be successfully implanted with postimplant audiological testing not statistically different than the younger cohort. The change in improvement between preimplant and postimplant test scores for the HINT and AZBio were not statistically significant between the Group 1 and Group 2.
In regards to complications, the differences between older and younger groups were insignificant with both groups having similar complication rates. The complications in both groups were minor and no major anesthetic complications, meningitis, or facial nerve injury was noted in either group. These complication rates are within the range of previously reported studies (13,14).
To our knowledge, no previous study has reviewed the impact of specific common comorbidities on complication rates in the elderly population. The current study reveals that the elderly population tends to have more comorbidities compared with the younger cohort. No specific comorbidity was found to have a significant contribution to the general complication rates in either the older or younger patient population.
Patient overall health, motivation, and comorbidities are factors to consider before cochlear implantation. Among the comorbidities present in the elderly patient population, no specific morbidity was shown to increase the risk of complications or adversely affect performance. While age should be considered in relation to overall health, speech outcomes and postoperative complications with a cochlear implant do not appear to be affected by age.
This study has several potential limitations including that the retrospective data may not account for complications that were not recorded in the electronic medical record. Likewise patients who may not have followed up may create a bias that could underestimate the complication rate.
Patients older than 70 who undergo cochlear implantation have similar success rates compared with their under 70-year-old counterparts as measured by speech understanding outcomes on HINT and AZBio testing. This elderly population tends to have multiple comorbidities compared with the younger cohort, however, these common comorbidities do not impact postoperative performance or complication rate. When determining cochlear implant candidacy, age alone should not be a concern. Overall health and motivation to succeed with an implant are likely the most important factors.
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Keywords:Copyright © 2017 by Otology & Neurotology, Inc. Image copyright © 2010 Wolters Kluwer Health/Anatomical Chart Company
Aging; AZBio; Cochlear implant; Cochlear implant complication; Comorbidities; Elderly; HINT; Outcomes