Influence of cochlear implantation on the working ability of hearing-impaired patients: A prospective study on potential influencing factors

Abstract

Purpose

This study evaluates the effect of cochlear implantation (CI) on work ability. The influences of quality of life (QOL), age, mental health, and hearing were analyzed.

Methods

Seventy-nine patients undergoing CI surgery were evaluated preoperatively and 12 months postoperatively. Work ability was evaluated using the Work Ability Index (WAI). QOL was assessed with the Nijmegen Cochlear Implant Questionnaire (NCIQ) and the WHOQOL-BREF. Mental health was assessed with the Patient Health Questionnaire.

Results

The WAI was unaffected by CI (Δ 0.8 ± 6.8, p = 0.42). No significant changes in WAI were observed for employees (Δ – 1.1 ± 5.7, p = 0.25) and pensioners (Δ −0.4 ± 7.8, p = 0.73). Patients without elevated depressiveness, stress, or somatoform symptoms had significantly better WAI.

The multiple regression analyses show that WHOQOL-BREF (ß = 0.49, p ≤ 0.001), age (ß = −0.34, p ≤ 0.001), and depressiveness (ß = 0.33, p = 0.04) were significantly associated with WAI. In the employee group, the NCIQ (ß = 0.58, p = 0.008) had the strongest association with the WAI.

Conclusion

Age, mental health, and QOL are predictive factors for work ability. This should be considered in the consultation and the rehabilitation process.

Keywords:

• Quality of Life
• Prom
• Age
• Stress
• Depressive Disorders
• AHL
• SSD
• Rehabilitation

1. Introduction

Currently, the global costs associated with unemployment and early retirement for people with hearing loss are conservatively estimated at $182.5 billion annually (Chadha et al., 2021). Due to the demographic shift in the German public, it can be presumed that the economic burden will increase with an aging population. A European study contextualized the relationship between chronic health problems and selection in the workforce, explaining that healthy applicants are more likely to be employed than job candidates with ill health, such as hearing disabilities (Schuring et al., 2007). Regardless of the extent of hearing loss, its impact on working life is mainly determined by the efficiency of clinical and rehabilitative interventions (Bolaños-Díaz & Calderón-Cahua, 2014; Chadha et al., 2021; Wilson et al., 2017). As stated in recent research, cochlear implant (CI) treatment increases employment opportunities, career prospects, executive functions, and job satisfaction (Fazel & Gray, 2007; Sarant et al., 2020). Additionally, the economic benefits of regaining hearing abilities with CI should not be underestimated. According to Clinkard et al., CI users displayed an increase in income more than 6 years postoperatively (Clinkard et al., 2015). The same study demonstrated that CI treatment is not only associated with patients’ personal gain but also has a broader economic benefit for society (Clinkard et al., 2015).

However, reaching conclusions about individual work ability solely based on functional parameters and how they are influenced by an intervention (e.g. exclusively based on hearing loss and its rehabilitation) does not fully consider the complex construct of work ability. Ilmarinen and Tempel understand work ability as the sum of factors enabling someone in a specific work situation to successfully cope with the work tasks assigned to them (Arbeitsfähigkeit 2010 was können wir tun, damit Sie gesund bleiben?, 2002). The Work Ability Index (WAI) was developed in the 1980s as a job-related measure considering the self-assessed work ability in relation to the physical and mental demands of the job as well as the employee’s health and resources (Tuomi et al., 1998) to make work ability measurable and thus comparable.

This validated measurement instrument is widely used internationally to address health economic or occupational health issues (Ilmarinen et al., 1991; Nygård et al., 1991; Tuomi et al., 1991). In some studies, the measuring instrument was also used to analyze the impact of specific diseases on the ability to work or the influence of interventions (Chang et al., 2020; Tański et al., 2022). For individual diseases, individual significant factors influencing the ability to work could be identified using this measurement instrument. In addition to purely functional parameters (Nygård et al., 1991), individual well-being and mental health are increasingly becoming the foci of these examinations (Ahlstrom et al., 2010; van den Berg et al., 2008). Various studies have evaluated the correlation between work ability and quality of life in diverse patient groups, such as those with rheumatoid arthritis (Tański et al., 2022) or musculoskeletal disorders (Chang et al., 2020; Monteiro et al., 2009; van den Berg et al., 2008). These studies determined a strong correlation between quality of life (QOL) and work ability. Furthermore, other studies demonstrated a strong association between work ability and physical and social health (Ahlstrom et al., 2010; Mateo-Rodríguez et al., 2021). Mental comorbidities have been identified as a strong predictor of lower-rated work ability. Depressive and somatoform disorders displayed a strong association with low work ability (Gilmour & Patten, 2007). Based on recent studies, not only is work impairment associated with depression and somatoform disorders, but stress also apparently correlates with a working disability (Ervasti et al., 2017; Khavanin et al., 2018).

Especially in the group of hearing-impaired people, a strong relationship between mental health and working ability can be assumed. The association between mental disorders and hearing loss has been a growing research topic, with multiple studies demonstrating that the prevalence of mental illnesses is higher in hearing-impaired people than those with normal hearing. Various studies associate hearing loss with a strong presence of depressive symptoms, somatoform disorders, and stress symptoms, as well as social isolation and desolation, which subsequently cause clinical depression and somatoform disorders (Bhatt et al., 2017; Brüggemann et al., 2017; Maharani et al., 2019). Moreover, higher stress levels represent a common mental illness associated with hearing impairment (Maharani et al., 2019).

Previous studies imply that adequate hearing rehabilitation, for example, through cochlear implantation in higher-degree hearing loss, leads to improved communication and consequently improved mental health (Brüggemann et al., 2017; Olze et al., 2022). Minimal research exists on the extent to which cochlear implantation can improve the working ability of postlingually deafened patients. Particularly, no studies exist on potential factors influencing the ability to work in this group of patients. Therefore, our study aimed to prospectively assess the influence of cochlear implantation on work ability. Additionally, potential predictors were determined within the framework of a multivariate analysis. The empirical selection of the factors to be considered (age, mental health, QOL, and hearing status) was based on the above-mentioned literature, considering the correlation and dependency structures identified.

2. Patients and methods

All adult patients scheduled for cochlear implantation from June 2020 to July 2021 were screened for participation in the study. Inclusion criteria were age ≥ 18, full legal capacity, German native speaker, and postlingual deafness. The language status was assessed preoperatively by hearing pedagogy. All patients who did not attend the 12-month appointment were excluded from the study. The first psychometric test battery was administered 1 to 2 weeks before surgery. Audiological testing was an important part of the complex outpatient diagnostic process prior to cochlear implantation in our department. The second measurement including audiological and psychometric measurements was taken at the 12-month visit during regular CI rehabilitation.

Institutional review board approval was obtained by the local ethical review committee (EK-247062020). All patients gave their informed consent. The study was conducted in accordance with the Declaration of Helsinki 1964.

2.1. Test battery

2.1.1. Demographic data

Demographic data was obtained preoperatively during the inpatient admission with an anamnesis questionnaire that enquired about the descriptive characteristics of the patient population: gender, age, medical treatment (if any) for the opposite ear, type of CI, implant company, speech processor, current occupation, duration of hearing loss, and professional degree.

2.1.2. Audiological assessment

A matrix test in noise was used with the Oldenburger sentence test (OLSA) to assess everyday speech comprehension as far as possible. The 50% speech reception threshold (SRT) was determined adaptively with a fixed noise level of 65 dB SPL. Under the presentation condition S0N0, speech and noise were displayed from the front at an angle of 0°. The OLSA was performed preoperatively and postoperatively in the bilateral hearing situation.

2.1.3. Psychometric test battery

1. Work Ability Index (WAI)

Developed in the 1980s by the Finnish Institute of Occupational Health, the WAI is a validated survey that examines the patient’s subjective work ability, defined as the ratio between the individual’s preconditions (health and resources) and the general work demands (Tuomi et al., 1998). Thus, the lower the total WAI score, the greater the discrepancy between the individual’s coping skills and the work requirements.

The WAI comprises seven subdomains (Table 1). The sums for each subdomain are added to form the total WAI score between 7 (poor working ability) and 49 (excellent working ability). The total WAI score can be grouped into four WAI categories, which additionally define a preventive strategy to either improve low WAI scores or maintain high WAI scores (Table 2). Unemployed participants were asked to correlate their working ability to daily life work (e.g. house, garden, or volunteer work).

1. Patient Health Questionnaire

Table 1 The subdomains of the WAI

Subdomain	Items
Current work ability compared to the best work ability ever achieved	1
Ability to work compared to the requirements of the work activity	2
Disease catalogue (only the medically diagnosed diseases are considered)	52
Estimated impairment of work performance from any diseases	1
Sick days in the past twelve months	1
Assessment of one's work	1
Mental performance reserve	3

Table 2 The four Work Ability Index (WAI) categories and their preventative strategies

WAI-Category	Total WAI-Score	Preventative Strategy
Critical working ability	7 to 27	Restore working ability
Moderate working ability	28 to 36	Enhance working ability
Good working ability	37 to 43	Support working ability
Very Good working ability	44 to 49	Preserve working ability

The German version of the Patient Health Questionnaire (PHQ-D) was used to assess psychological health (Gräfe K et al., o. J.). The PHQ-D has been developed to screen for mental disorders in primary care. It is based on diagnostic criteria from the fourth edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (Guze, 1995).

Depressiveness:

The depression module (PHQ-9) of the PHQ-D is a screening tool used in numerous patient populations to quantify the severity of patient-reported depressive symptoms (‘depressiveness’). Patients rate the occurrence of depressive symptoms within the last 2 weeks on a 4-point scale from 0 (‘not at all’) to 3 (‘nearly every day’). The severity of depressive symptoms was analyzed as a continuous score from 0 (none) to 27 (severe).

Stress:

The PHQ stress module measures psychosocial stress during the last month using 10 items, including health, work/financial, social, and traumatic stress. Patients rate the severity of stress on a scale of 0 (‘not at all bothered’) to 2 (‘bothered a lot’). The severity of stress was analyzed on a continuous scale from 0 (none) to 20 (severe).

Somatoform

The ‘somatoform symptoms’ scale score includes 15 somatic symptoms corresponding to the 15 most common physical complaints of outpatients as well as the most important DSM-IV criteria for somatization disorders. This ‘somatoform module’ is also called ‘PHQ-15.’ The PHQ-15 score is formed from the 13 somatoform module items and 2 depression module items. The somatoform module items are marked with 0 (‘not impaired’), 1 (‘slightly impaired’), or 2 (‘strongly impaired’). The scale sum value thus lies between 0 and 30.

According to the PHQ-D manual, a cutoff value of 5 points can be set for each mental disorder. Therefore, scale values below 5 points indicate that the participants display a lack of depressive symptoms, a lack of somatoform symptoms, and a low stress severity level.

1. Quality of life

WHOQOL-BREF

The WHOQOL-BREF is an abbreviated version of the original WHO-QOL-100. Developed by the World Health Organization (WHO), the questionnaire was validated and translated into over 30 languages (The WHOQOL Group, 1998). The questionnaire comprises four domain scores (physical, psychological, social, and environmental health), each representing one aspect of QOL. The mean scores are converted to a 0–100 scale to create a comparable dataset. The total score is calculated from the mean values of all subscores. Higher scores indicate better generic QOL.

Nijmegen Cochlear Implant Questionnaire

The Nijmegen Cochlear Implant Questionnaire (NCIQ) is specifically designed to evaluate the QOL of CI patients (Hinderink et al., 2000). The NCIQ has also been validated in German by (Plath et al., 2021). It comprises 60 questions divided into three main domains (physical, mental, and social functionality) and six subdomains (basic sound perception, advanced sound perception, speech production, self-esteem, activity limitations, and social interactions). The total NCIQ score is computed as the mean of the six subdomain averages. A higher score reflects a better subjective assessment of disease-specific QOL.

2.2. Statistical analysis

The statistical evaluation was performed with the software IBM SPSS Statistics, Version 28 (New York, United States of America). Data were shown as mean ± standard deviation (SD). In the presence of a normal distribution, the preoperative and postoperative datasets of working ability and the influencing factors were assessed with paired samples t test. The preoperative and postoperative WAI score differences between two groups were determined solely with the unpaired samples t test. Differences between three groups were analyzed by univariate analysis of variance (ANOVA). Multiple linear regression analyses were conducted to determine the effect of psychological health, QOL, age, and hearing status on outcome scores. Bivariate associations were described using the Pearson correlation coefficient (r). The McNemar-Bowker test was used to analyze the pre-postoperative shift in WAI clusters. The significance level was defined at p < 0.05.

3. Results

A total of 101 potential participants were initially admitted to this study, and 79 patients could be fully evaluated preoperatively as well as postoperatively. Consequently, 22 (21.8%) patients were excluded from the data pool due to incomplete datasets. Eleven patients (10.9%) did not want to retake the psychometric measurements for personal reasons, nine patients (8.9%) did not attend the 12-month appointment due to the COVID-19 pandemic, and in two patients (2.0%), the implant had to be changed due to an implant defect. Table 3 lists the demographic characteristics of the patient population. Based on the current German retirement age of 67, 68.4% of the study’s participants (n = 54) were of working age, whereas 31.6% (n = 35) were above the working age of 67.

Table 3 Demographic data (n = 79)

Parameter		Frequency out of n = 79 (absolute number)
Age	57.7 ± 16.0 years (mean ± SD)
Gender	Female	55,7% (44)
	Male	44,3% (35)
Side	Left	59,5% (47)
	Right	40,5% (32)
Hearing Status	SSD	21,5% (17)
	AHL	21,5% (17)
	Bilateral hearing loss	57.0% (45)
Hearing solution contralateral ear	Hearing Aid	39.7% (31)
	Cochlear implant	33.3% (26)
	Active Middle Ear Implant or Bone Conduction Implant	14.1% (11)
	None	12.8% (10)
Implant company	Cochlear	59.5% (47)
	MED-EL	34.2% (27)
	Advanced Bionics	6.3% (5)
Working status	Employees	49.4% (39)
	Old-age pensioners	39.2% (31)
	Disability pensioners	7.6% (6)
	Unemployed	2.5% (2)
Professional degrees	Vocational training	55.7% (44)
	Study degree	40.5% (32)
	In training	2.5% (2)
	No professional degree	1.3% (1)

3.1. Work ability

Based on the evaluation of the preoperative (30.2 ± 8.6) and postoperative (31.0 ± 9.1) WAI scores, working ability did not significantly change 12 months after cochlear implantation (Δ 0.8 ± 6.8, p = 0.42, Fig. 1). Nevertheless, an improvement in the assigned WAI category to a better WAI category after CI surgery was observed in 59.4% (n = 47) of the patients (Table 4). However, 11.4% (n = 9) of patients reported a worsening in the WAI category 12 months after cochlear implantation. This frequency change in the WAI classes is significant (p < 0.001).

Figure 1 Comparison of the working ability of all patients (n = 79) before and 12 months after cochlear implantation. Work ability is measured by the Work Ability Index (WAI). Higher values indicate a better work ability. The results show no significant (n.s.) change after cochlear implantation.

Table 4 Change in Work Ability Index (WAI) clusters pre- to postoperative (p < 0.001). (The patients with an improvement in the WAI cluster are marked in light grey.)

		Postoperative WAI category
		1 Critical	2 Moderate	3 Good	4 Very good
Preoperative WAI category	1 Critical	19% (15)	1.3% (1)	1.3% 1)	7.6% (6)
	2 Moderate	7.6% (6)	19% (15)	10.1% (8)	11.4% (9)
	3 Good	1.3% (1)	2.5% (2)	13.9% (11)	3.8% (3)
	4 Very good	0% (0)	0% (0)	0% (0)	1.3% (1)

3.2. Potential influencing factors for work ability

3.2.1. Hearing status

The influencing factor speech comprehension in noise, analyzed using the OLSA, showed a significant improvement (Δ −3.1 ± 5.4 dB, p < 0.001) after cochlear implantation (preoperative 3.5 ± 0.9 dB versus postoperative 0.5 ± 0.5 dB). Based on the univariate analysis, no significant association existed between postoperative SRT and WAI score (r = 0.039, p = 0.74).

No significant differences were obtained in the postoperative WAI scores (p = 0.18) stratified for the three types of hearing loss (AHL, SSD, and bilateral hearing). None of these three patient groups showed a significant improvement in work ability after cochlear implantation (Table 5).

Table 5 Comparison of pre- and postoperative work ability measures by the Work Ability Index (WAI), stratified by gender, type of hearing loss, psychological comorbidity, professional degree, and working status

		WAI total score
		Preoperative	Postoperative
Total group	n = 79	30.2 ± 8.6	31.0 ± 9.1
Gender	Male (n = 35)	30.4 ± 7.7	29.7 ± 9.8
	Female (n = 44)	30.0 ± 9.3	32.0 ± 8.5
Age	< 67 years (n = 44)	31.2 ± 9,2	32.0 ± 10.3
	≥ 67 years (n = 35)	28.4 ± 7,2	29.2 ± 6.1
Kind of hearing loss	SSD (n = 17)	33.9 ± 9.8	34.1 ± 11.0
	AHL (n = 17)	28.4 ± 7.0	28.2 ± 7.7
	Bilateral hearing loss (n = 45)	29.8 ± 8.7	30.9 ± 8.7
Depressiveness	Non-elevated symptoms^1 (n = 42)	32.8 ± 7.2^###b	33.3 ± 8.3^##a
	Elevated symptoms ^2 (n = 37)	26.6 ± 9.5	27.5 ± 9.2
Stress	Non-elevated stress level ^3 (n = 54)	31.3 ± 8.6	32.3 ± 9.3^#c
	Elevated stress level ^4 (n = 25)	28.0 ± 8.4	28.4 ± 8.4
Somatoform	Non-elevated symptoms (n = 29) ^5	33.8 ± 7.3^##d	34.6 ± 9.0^##d
	Elevated symptoms (n = 50) ^6	28.3 ± 8.6	29.1 ± 8.2
Professional degree	Study degree (n = 32)	31.5 ± 7.2	33.6 ± 7.0
	Vocational training (n = 44)	29.4 ± 9.1	29.6 ± 9.7
Working status	Pensioners (n = 37)	26.2 ± 8.9^###e	27.3 ± 8.2^###e
	Employees (n = 39)	34.0 ± 6.2	34.8 ± 8.1

Data shown are mean ± standard deviation, Higher WAI score indicate better work ability

AHL, asymmetric hearing loss (defined as an interaural asymmetry of more than 30 dB, whereas the better hearing ear has less or equal to 60 dB HL and more than 30 dB HL at one or more frequencies across the pure tone average)

SSD, single sided deafness (unilateral deafness and contralateral normal hearing with a pure tone average less or equal to 30 dB HL)

¹ PHQ 9 < 5, ² PHQ 9 ≥ 5, ³ PHQ stress module< 5, ⁴ PHQ stress module ≥ 5, ⁵ PHQ 15 < 5 ⁶ PHQ 15 ≥ 5,

^##a p < 0.01, ^###b p < 0.001 significant difference between patient with and without elevated depressive symptoms

^#c p < 0.05, significant difference between patient with and without elevated stress level

^##d p < 0.01, significant difference between patient with and without elevated somatoform symptoms

^###e p < 0.001, significant difference between employers and pensioners

3.2.2. Age

No significant improvement was found in the WAI score in either age group (patients <67 and patients ≥ 67 years) analyzed (Table 5). When comparing both age groups, no significant difference was found in the postoperative WAI score (p = 0.19). The correlation analysis displayed a low negative association between postoperative working ability and age, demonstrating that the postoperative working ability significantly decreased as age increased (Fig. 2, r = −0.27, p = 0.02).

Figure 2 Association of postoperative work ability and patients’ age (total group, n = 79), Work ability is measured by the Work Ability Index (WAI). Higher values indicate a better work ability. *p ≤ 0.05

3.2.3. Quality of life

The general QOL measured with the WHOQOL-BREF did not show a significant change 12 months after the CI treatment (68.9 ± 12.6 versus 68.5 ± 14.5 p = 0.72). Based on the univariate analysis, a moderate positive association existed between the postoperative general QOL and postoperative WAI score (Fig. 3A, r = 0.614, p < 0.001). The evaluation of the preoperative and postoperative mean NCIQ total scores displayed a significant improvement (50.1 ± 14.1 versus 67.2 ± 13.6, p < 0.001) 12 months after the CI treatment. A low positive association existed between the postoperative NCIQ total score and WAI score (Fig. 3B, r = 0.⁠41, p < 0.001).

Figure 3 Association of postoperative work ability and (A) postoperative general quality of life (QOL) and (B) disease-specific QOL. Work ability was determined using the Work Ability Index (WAI), general QOL using the WHOQOL-BREF total score and disease-specific QOL using Nijmegen Cochlear Implant Questionnaire (NCIQ), Higher WAI values indicate a better work ability. Higher QOL scores indicate better QOL. ***p < 0.001.

3.2.4. Psychological comorbidities

Regarding PHQ-D scores, no significant change occurred in patients’ depressiveness (5.4 ± 4.3 versus 4.9 ± 3.9, p = 0.⁠12, somatization 6.3 ± 4.8 versus 7.0 ± 4.8, p = 0.08, and stress perception 3.8 ± 3.5 versus 4.1 ± 3.4, p = 0.49) after cochlear implantation. Significant associations existed between these psychological comorbidity scores and postoperative WAI scores (Fig. 4A–C).

Figure 4 (A - C) Correlation of postoperative work ability (expressed by WAI total score) and mental health (depressiveness, stress, somatoform symptoms), (D) comparison of patients with preoperative non-minimal depressive symptoms (PHQ-9 < 5) versus patients with depressive symptoms (PHQ-9 ≥ 5); (E) comparison of patients with minimally pronounced psychosocial stressors (PHQ stress module < 5) versus patients with more pronounced stressors (PHQ stress module ≥ 5); (F) comparison of patients without pronounced somatoform symptoms (PHQ-15 < 5) versus patients with more somatoform symptoms (PHQ-15 ≥ 5); WAI, Work Ability Index, PHQ, Patient Health Questionnaire, Higher WAI values indicate a better work ability. Higher PHQ scores indicate worse mental health. ***p < 0.001, ** p < 0.01, *p ≤ 0.05

Participants with high stress severity levels, present somatoform symptoms, and relevant depressive symptoms rated their postoperative working ability significantly worse (Fig. 4E–F) than patients with a low stress severity level (Δ 3.9 ± 2.2, p = 0.04) and a lack of somatoform (Δ 5.48 ± 2.01, p = 0.008) or depressive symptoms (Δ 5.73 ± 2.04, p = 0.006).

3.2.5. Working status

Working ability was further analyzed regarding the two predominant occupational subpopulations of this study: employed patients and pensioners (including old age pensioners and disability pensioners). When comparing the postoperative working abilities of employees and pensioners, the analysis revealed a significant difference between the two postoperative WAI scores (p < 0.001, Table 5). However, the analysis of pre- and postoperative WAI scores for both employed and pensioned participants did not show a significant change after the CI treatment (Fig. 5A, employed patients: mean difference −1.1 ± 5.7, p = 0.25, Fig. 5B pensioned participants: mean difference −0.4 ± 7.8, p = 0.73).

Figure 5 Comparison of the working ability of all patients stratified by different working status, (A) employees (n = 39) and (B) pensioners (n = 37), The results show no significant (n.s.) change after cochlear implantation. WAI, Work Ability Index. Higher WAI values indicate a better work ability.

Furthermore, the ability to work was stratified according to the type of professional degree. A distinction was made between patients with a degree from a university or university of applied sciences (n = 32) and patients with vocational training (n = 44). The patients with university degrees tended to show better postoperative work ability than the patient group with vocational training (Table 5). However, the difference (Δ 4.0 ± 2.1, p = 0.06) was not significant. No significant improvement in WAI due to cochlear implantation was demonstrated for any of these patient groups.

3.2.6. Multivariate analyses

Multivariate analyses for postoperative WAI were performed with explanatory variables including generic QOL (WHOQOL-BREF total score), disease-specific health-related QOL (NCIQ total score), age, hearing status (OLSA), and psychological comorbidities (stress perception, depressiveness, and somatoform symptoms). The results of the multiple regression analyses showed that in the total patient group, even when adjusting for these factors, generic QOL, age, and depressiveness remained significantly associated with higher WAI scores (Fig. 6). Multivariate analysis was additionally stratified by working status. In the employees’ group (Fig. 7A) the postoperative disease-specific QOL (postoperative NCIQ scores) was the strongest influencing factor. When evaluating the influences of these factors on the postoperative WAI in the pensioner group (Fig. 7B), generic QOL and depressiveness had the strongest influences on WAI when adjusted for the possible influencing factors listed.

Figure 6 Multiple regression analysis of factors influencing postoperative work ability (overall group, n = 79); WAI, Work Ability Index. Mental Health (depressiveness, somatoform symptoms, stress) were evaluated by Patient Health Questionnaire (PHQ-D), general QOL using the WHOQOL-BREF total score and disease-specific QOL using Nijmegen Cochlear Implant Questionnaire (NCIQ), hearing in noise by the Oldenburger sentence test. Data shown are mean ± SD; ß regression coefficient; ***p ≤ 0.001, *p ≤ 0.05, n.s. not significant.

Figure 7 Multiple regression analysis of factors influencing postoperative NCIQ, stratified by working status, (A) employees (n = 39), (B) pensioners (n = 31), WAI, Work Ability Index. Mental Health (depressiveness, somatoform symptoms, stress) were evaluated by Patient Health Questionnaire (PHQ-D), general QOL using the WHOQOL-BREF total score and disease-specific QOL using Nijmegen Cochlear Implant Questionnaire (NCIQ), hearing in noise by the Oldenburger sentence test. Data shown are mean ± SD; ß regression coefficient; ***p ≤ 0.01, *p ≤ 0.05.

4. Discussion

Unaddressed hearing loss can negatively impact many aspects of daily life: communication, the development of language and speech in children, cognition, education, employment, mental health, and interpersonal relationships (Chadha et al., 2021). Therefore, it is understandable that hearing disorders can also decisively influence the ability to work of those affected.

Numerous studies have demonstrated the positive effect of cochlear implantation on audiological performance (Daher et al., 2023; Ma et al., 2023) and QOL, but also on psychological comorbidities (Brüggemann et al., 2017; Häußler et al., 2020; Ketterer et al., 2020; Olze et al., 2022). This generated the hypothesis that a cochlear implant can contribute to improved work ability by improving speech comprehension and QOL. To date, only sporadic studies exist on the impact of cochlear implantation on working life (Goh et al., 2016). Work ability has not been addressed in a standardized way in these studies so far.

When comparing the mean postoperative WAI with the German public, the patient cohort of this study had an average postoperative WAI score of 31.0 ± 9.1, whereas the German reference group displayed a mean score of 40.2 ± 6.2 (Freyer, 2019). Therefore, based on the evaluation with the WAI categories, CI users of our analysis estimated their postoperative work ability only as ‘moderate,’ which appears much lower than that of most Germans who assessed their work ability as ‘good.’ These findings reaffirm the negative correlation between hearing disability and work ability (Gupta et al., 2023). Regarding the age distribution of the participants, 68.4% of the patients (n = 54) were of working age between 18 and 67. Consequently, less than one-third of the participants (31.6%, n = 35) were above the German retirement age of 67. However, when analyzing the occupations of the study cohort, less than half of the participants (49.4%, n = 39) were employed, and more than one-third of the patients (39.2%, n = 31) were pensioners. This leads to the conclusion that a substantial discrepancy exists between the number of hearing-impaired participants who should hypothetically be working and the number of people actively employed. Moreover, our study established that work ability did not significantly improve after CI treatment. However, a significant increase in ‘good’ and ‘very good’ work ability postoperatively was discerned when comparing preoperative and postoperative WAI categories. Similar findings were presented in a study from New Zealand, which also identified a positive influence of CI treatment on employment; however, the outcome lacked statistical significance (Goh et al., 2016).

Adaptation processes could be one cause of the lack of improvement in the ability to work (Boothroyd, 2007). Some of the long-term hearing-impaired patients may have found jobs with lower communication requirements or have developed strategies to cope with the demands of working life despite their hearing loss. It is also notable that, on average, the patients in this study were aged 57.7 ± 16.0. Considering that older people are less likely to acquire new habits and skills, the overall demographic of CI patients could display lower levels of ambition to improve their work ability to attain a promotion or higher job position (Monteiro et al., 2009; von Bonsdorff et al., 2012). Another reason for the lack of evidence of improvement will be the short follow-up period of 1 year. Health economic studies on measures to improve working ability often show only very small effects after long observation periods (Oakman et al., 2018).

Consistent with studies from other medical fields, our study also showed a significant association of QOL with work ability (Chang et al., 2020; Tański et al., 2022). While the disease-specific QOL primarily influenced the ability to work in our group of employed people, the general QOL was decisive for assessing the ability to work in the group of pensioners. Notably, at this point, a bidirectional relationship can be assumed between the factors QOL and work ability, which should be analyzed in more detail in further studies. Speech comprehension did not correlate with work ability in our study. This is consistent with other studies, which also showed no correlation of hearing with the patient-reported outcome measures (Capretta & Moberly, 2016; Lailach et al., 2018, 2021; Vasil et al., 2020). Mental health was found to be another important factor influencing the ability to work in our study. Patients with increased depressiveness, increased expression of somatoform symptoms, and high stress perception showed a significantly poorer ability to work. In our multivariate analysis, the significant influence remained in the total group and the group of pensioners, even after adjustment for the other potential influencing factors. In our study, 46.8% of the patients had relevant depressive symptoms. The high rate of depressive symptoms in hearing-impaired people has been documented in previous studies. Earlier studies showed depression rates of 40%–60% in hearing-impaired people or a rate almost five times higher than the general population (Knutson & Lansing, 1990; Sherbourne et al., 2002; Thomas, 1984). In our study, 31.6% reported increased stress levels, representing only a slight increase compared to the general European population during the COVID-19 pandemic (27.41%) (Mahmud et al., 2021). In our study, 50 out of 79 patients (63%) had somatoform symptoms. Meta-analyses have found a lifetime prevalence of 40% for somatoform disorders (Haller et al., 2015). Our study thus indicates an increased prevalence of somatoform disorders in patients with profound hearing loss.

Overall, the results of our study suggest that the purposeful modulation of mental comorbidities during CI (re)habilitation can lead to an improvement in work ability after CI treatment. In addition to screening and primary psychological counseling as part of CI (re)habilitation, additional psychotherapy is recommended for patients with psychological comorbidities. It is therefore crucial to incorporate psychological and psychosomatic guidance during CI (re)habilitation to comprehensively promote and maintain work ability after CI treatment (Brüggemann et al., 2017). The expansion of the therapy spectrum and multiprofessionality, including psychological support, is now established in many centers to fully consider the biopsychosocial concept (Tucker et al., 2011). Psychological counseling and guidance throughout the CI rehabilitation process significantly influence the patient’s motivation and basic attitude towards therapeutic work as well as hearing impairment generally. Moreover, hearing-impaired people benefit tremendously from workplace accommodations and welfare to promote their work ability (Hua et al., 2015; Svinndal et al., 2018). It is therefore essential to incorporate these services during CI (re)habilitation to develop strategies for job modifications and inclusivity at the workplace for patients adapting to CI. CI (re)habilitation should also include a psychosocial approach to overcome present stigmas and teach CI users psychological facilitators for work life with a CI. This would expedite the transition from working with hearing impairment to restored hearing abilities with the CI and could simultaneously maximize the improvement in the patients’ work ability.

An important consideration is that the COVID-19 pandemic has created profound changes in work life, reshaping how people work, communicate, and collaborate. One of the most notable shifts during the pandemic was the rapid adoption of remote work. Furthermore, the pandemic accelerated the digital transformation in the workplace. Companies that had previously relied heavily on in-person interactions were forced to rapidly adapt to the digital landscape (Galanti et al., 2021). These changes, along with smaller work groups and progressively important mail traffic, could have unintentionally improved the work ability of hearing-impaired people.

The outcome parameter of this study was evaluated with the WAI questionnaire, which is not specifically designed for assessing the work ability of hearing-impaired people. This can also lead to low responsiveness. Likewise, pensioners were evaluated with the WAI rather than using a questionnaire focusing on evaluating work ability specifically for pensioners. Consequently, a questionnaire evaluating disease-specific work ability for CI users for different age groups could enhance the assessment of the outcome parameter of this study and emphasize the differential influences of various work ability parameters between pensioned and employed CI patients. Additionally, the WHOQOL-BREF was used for all age groups. The additional use of the WHOQOL-OLD would have led to an additional time burden for the elderly patients.

The present study explored factors influencing the ability to work in CI patients, which are known from other areas of medicine, for the first time. However, further disease-specific and non-disease-specific factors are required when considering the complex construct of work ability. For example, the effect of tinnitus and dizziness on work ability should be analyzed. Furthermore, factors such as coping strategies, work environment, work community, management, values, attitudes, motivation, competences, and work experiences should be assessed. Furthermore, the operational environment (e.g. social networks, infrastructure, and labor market) should be integrated into the assessment of work ability (Ilmarinen, 2009, 2019; Ilmarinen et al., 2005). Additionally, it must be considered that an inhomogeneous patient group was analyzed in the current study. The patients showed inhomogeneity in hearing situation, age, and occupational status. However, splitting the total group into small subgroups showed significant differences only for the two occupational groups (employers/pensioners). Work ability assessment in a larger homogeneous group would be desirable. This explorative study can provide a basis for this.

5. Conclusion

Cochlear implantation does not improve work ability after 12 months. Patients undergoing CI treatment should receive preliminary counseling to inform them about realistic expectations. The development of strategies to help patients with CI improve their ability to work is urgently needed. Additionally, among the covariates, mental health and QOL were salient factors associated with work ability. Health promotion programs to improve the mental health of CI patients could be another means to increase their work ability.

Disclaimer statements

Contributors None.

Funding None.

Conflicts of interest None.

Ethical standards All procedures performed in studies involving human participants were in accordance with the ethical standards of local ethical review committee (EK 166042017) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent Informed consent was obtained from all the participants.

Data availability statement The data that support the findings of this study are available on request from the corresponding author (SL).

Additional information

Notes on contributors

Susen Lailach

Susen Lailach is a specialist physician for otorhinolaryngology and phoniatrics and pediatric audiology at the ORL-HNS Department of the University Hospital Dresden.

Johanna Martin

Johanna Martin graduated in dentistry, a PhD student at the ORL-HNS Department of the University Hospital Dresden.

Paula Stephan

Paula Stephan graduated in dentistry, a PhD student at the ORL-HNS Department of the University Hospital Dresden.

Dominique Kronesser

Dominique Kronesser is a Speech and Language Therapist (M. A.) and therapeutic director of the Saxonian Cochlear Implant Centre Dresden.

Thomas Zahnert

Thomas Zahnert since 2004 he has been the director of the ORL-HNS Department of the University Hospital Dresden.

Marcus Neudert

Marcus Neudert is a medical director of the Ear Research Center in Dresden (ERCD) and a senior physician at the ORL-HNS Department of the University Hospital Dresden.