Hearing impairment is a common chronic condition in The Netherlands and worldwide. Although the vast majority of adults with hearing impairment has already retired [1
], there is a considerable number of younger persons with hearing impairment still active in the labor force. The prevalence of hearing impairment in the Dutch labor force is about 3% (255.000 people) [2
]. These numbers are comparable with estimations of the global burden of hearing loss according to the World Health Organization (WHO) [3
]. It is well established that hearing impairment is age-related [3
]. The expectation is that the number of employees with hearing impairment will increase in the near future because of the ageing population, which have a higher prevalence of hearing impairment, together with plans to increase the retirement age. A problem for hearing impaired employees is that occupations nowadays more and more depend on communication skills. As described by Ruben [4
], the modern western economics underwent fundamental changes during the second half of the 20th century. While society was largely dependent on manual labor in the past, occupations today rely more on communication abilities. This implies a greater burden on people suffering from hearing impairment. Altogether, this may lead to an increasing number of hearing impaired employees who need help for problems in the workplace situation.
So far, only a few studies have addressed the impact of hearing impairment on work performance. The studies that have been revealed that there is a range of concerns and problems that hearing impaired employees are likely to experience. Most frequently reported issues are lack of control, problematic functioning in environmental noise, concerns about job safety, sick leave, and the fear to loose employment [5
]. Furthermore, fatigue and distress are considered as effects of hearing impairment arising due to the constant need to adapt to, and to compensate for the hearing impairment [9
]. 'Need for recover after work' refers to the degree to which employees are able to recover from fatigue and distress after one day of work [10
]. It is an important factor influencing an individual's physical and mental functional status, and thus the ability to cope with work. The model of Job Demand Control (JDC) makes a distinction between different psychosocial work conditions, such as psychological job demands and job control [11
]. According to this model need for recovery can be seen as a short term effect of work [10
]. A study by Nachtegaal et al. [12
] showed significantly higher levels of 'need for recovery after work' among hearing impaired employees (46%), compared to normally hearing colleagues (38%). They also found that for every dB signal-to-noise ratio (dB SNR) poorer hearing test score, the need for recovery after work increased with 1.4 points. Due to these issues, hearing impaired employees are likely to experience problems varying from direct auditory dysfunctioning to more secondary issues such as psychosocial problems.
Hearing impairment has consequences not only for the working hearing impaired individuals themselves, but also for companies and society. Previous studies showed that hearing impaired people are overrepresented in the group taking sick leave from work [13
] and that these persons received more health care [14
] in comparison with normal hearing colleagues. This results in higher costs for both the company and society. Additionally, Mohr et al. [15
] showed that most of the societal costs of hearing impairment are caused by reduced working productivity due to presenteeism (i.e., being present at work but not functioning at full capability).
A search of the literature showed that interventions specifically supporting hearing impaired employees have scarcely been described. Programmes, other than those aimed at preventing noise-induced hearing loss, for example the protocol of the Dutch Board for Occupational Medicine (NVAB) [16
], are practically non-existent. It seems that in current audiological practices, the specific needs of hearing impaired people with work-related difficulties are not dealt with in a standard approach. In The Netherlands, usual care to handle with hearing impairment at work consists of the common guidance and (workplace) advices from the occupational physician (OP). The OP can refer the employee to the general practitioner, to the ear nose and throat (ENT) specialist, or to an audiologic clinic for further audiological diagnostics and care [17
]. The possible hearing aid fitting is done by a hearing aid dispenser. There is anecdotal evidence indicating that this usual care does not solve all the problems at the workplace that arise from hearing impairment [8
]. It is suggested that a timely coordination of multidisciplinary services is required to fully support and facilitate employees with hearing impairment [8
]. Additionally, it is argued that if not taken care adequately, disabilities in the workplace due to hearing impairment may result in a substantial health problem and productivity loss with substantial costs for the society as a whole. Therefore, interventions in aural rehabilitation specifically focusing on work-related problems for hearing impaired employees are needed to reduce costs.
An integrated care programme to facilitate and improve the working situation for hearing impaired employees was developed by Kramer et al. [18
]. The International Classification of Functioning, disability and health (ICF) provided the theoretical framework for this integrated care programme [19
]. In this framework, not only the individual's health condition (hearing impairment at the workplace) but also environmental and personal factors play an important role. A hearing impaired person's disability and functioning should be seen as outcomes of interactions between an individual's health condition, activities, participation, environmental factors (room acoustics, detection of sounds, colleagues, task schedules), and personal factors (age, cognitive capacities, coping styles, education). The integrated care programme for hearing impaired employees, the Vocational Enablement Protocol (VEP), addresses all these factors in the ICF model to improve the participation of hearing impaired employees. The VEP integrated care programme consists of a multidisciplinary assessment of auditory function (body structures and functioning), personal characteristics (personal factors), workplace characteristics (environmental factors), and work demands (activities, participation). The main aim of the VEP integrated care programme is to facilitate participation in and retention of work for hearing impaired employees.
Satisfaction and experiences with the VEP integrated care programme is already evaluated and described elsewhere [18
]. However, it is not yet known whether this integrated care programme is effective and cost-effective in comparison with usual care. Randomized controlled studies to examine the cost-effectiveness of an intervention are still rare in the field of audiology. This paper describes the design of a randomized controlled trial to evaluate the effectiveness and cost-effectiveness of the VEP integrated care programme compared with usual care in reducing the 'need for recovery after work'.