Vocational rehabilitation is defined as a multi-professional evidence-based approach that is provided in different settings, services, and activities to working age individuals with health-related impairments, limitations, or restrictions with work functioning and whose primary aim is to optimize work participation [1]. While this definition is comprehensive and fits within ICF, it is also quite complex. In simple language, vocational rehabilitation can also be defined as “anything that helps someone with a health problem to stay at, return to, and remain in work” [2].

One of the most comprehensive reviews of the scientific literature on vocational rehabilitation for workers with common health problems was published in 2008 by Waddell, Burton, and Kendell [2]. This review demonstrated that there is strong evidence that vocational rehabilitation interventions for workers with CMPC can be effective in terms of work outcomes. For many years the strongest evidence was on low back pain, but more recent evidence shows that the same principles apply to most people with the most common CMPCs such as complaints of pain in the neck, shoulders, and arms. It was also demonstrated that from a societal perspective, vocational rehabilitation in patients with CMPC has a good business case, indicating that society as a whole may benefit from investments in vocational rehabilitation. Although estimates vary, a ratio of 1:5 was mentioned: for every currency unit invested in vocational rehabilitation, the societal return will be fivefold [2].

Vocational rehabilitation principles and interventions are fundamentally the same for work-related and other comparable (non-work-related) health conditions, irrespective of whether they are classified as injury, condition, or disease. Healthcare has a key role, but vocational rehabilitation is not a matter of healthcare alone. Employers also have a key role – there is strong evidence that proactive company approaches to sickness, including temporary provision of modified work and accommodations, are effective and cost-effective [3], although there is less evidence on vocational rehabilitation interventions in small and medium enterprises. Overall, the evidence shows that effective vocational rehabilitation depends on work- and worker-focused healthcare and accommodating workplaces; both are necessary as they are interdependent and must be coordinated simultaneously [2].

The concept of early intervention is central to vocational rehabilitation, because the longer a worker is off work, the greater the obstacle to return to work and the more challenging vocational rehabilitation becomes. It is simpler, more effective, and cost-effective to prevent people with a musculoskeletal condition from going on to a long-term sickness absence. A “stepped-care approach” starts with mono-disciplinary, low-intensity, and low-cost interventions, which will be adequate for most sick or injured workers (e.g., physical therapy, education, RTW coaching), and provides progressively more intensive and structured interventions for those who need additional help to return to work (from back schooling in a secondary care setting to multidisciplinary vocational rehabilitation in a tertiary care setting). This approach allocates resources most appropriately and efficiently to meet individual and payers’ needs. Effective vocational rehabilitation depends on communication and coordination between the key players – particularly the individual, healthcare, and workplace.

Given that vocational rehabilitation is about helping people with health problems stay at, return to, and remain in work, the question is how to make sure that everyone of working age receives the help they require. This should start from the needs of people with health problems at various stages, build on the evidence about effective interventions, and consider potential resources and the practicalities of how these interventions might be delivered. From this perspective, there are three broad types of workers, who are differentiated mainly by the duration out of work and who have correspondingly different needs: workers who are absent short term (less than 6 weeks), intermediate (between 6 weeks and 12 months), and long term (more than 3 months) [3]. There is also a fourth type of worker that has recently started to gain attention: those workers who manage to stay at work despite a CMPC [4].

In the first few weeks, most people with CMPC can be helped to return to work by following a few basic principles of healthcare and workplace management. For the diagnosis of acute nonspecific low back pain, evidence-based European guidelines [5, 6] recommend to perform a case history and brief examination. If history taking indicates possible serious pathology or nerve root syndrome, more extensive physical examination including neurological screening when appropriate should be carried out. In this stage, it is also recommended to be aware of psychosocial factors and to review them in detail if there is no improvement. Diagnostic imaging tests (including X-rays, CT, and MRI) are not routinely indicated for nonspecific low back pain. Those patients who are not resolving within a few weeks after the first visit or those who are following a worsening course should be reassessed.

With regard to treatment, evidence-based guidelines recommend healthcare workers to [6]: give adequate information and reassurance; not prescribe bed rest as a treatment; advise patients to stay active and continue normal daily activities including work if possible; prescribe medication, if necessary for pain relief, preferably to be taken at regular intervals, being paracetamol and NSAIDs as the first choice and second choice, respectively; consider adding a short course of muscle relaxants on its own or added to NSAIDs, if paracetamol or NSAIDs have failed to reduce pain; and consider (referral for) spinal manipulation for patients who fail to return to normal activities. At the acute stage, workers may need to temporarily perform modified work or at reduced hours. Temporary refrain from work may be considered if modified work is not an option, but this should be followed by (gradual) re-engagement with work activities, whenever feasible.

For workers with subacute CMPC and sick leave for more than 4–8 weeks, multidisciplinary rehabilitation programs in occupational settings may be an option to offer to workers who need additional help to return to work. However, within the stepped-care approach, diagnostic triaging is needed to screen those who can benefit and to screen out those who will not benefit, for example, whose course of recovery may still be considered favorable without healthcare interventions. At this stage, the advice for vocational rehabilitation will be a trade-off between prognosis, costs, and benefits. Those with a prognosis that is unfavorable based on bio-, psycho-, or social factors, even though the time off work may be limited, may still be advised to follow vocational rehabilitation. The “risk” that the individual worker will regain normal work without healthcare interventions, because of the favorable prognosis based purely on limited time off work, should be weighed against the risk of not regaining work because of unfavorable other prognostic factors (“too much, too soon, and too costly” versus “too late”). At this point in time, however, validated instruments to assist with these decisions are unavailable.

For workers who are out of work more than about 6 months, multidisciplinary rehabilitation is recommended for workers with CMPC [2, 5]. There is strong evidence that multidisciplinary vocational rehabilitation is effective to facilitate work outcomes [2, 5]. However, there are also major challenges that accompany vocational rehabilitation. Even though its effectiveness has been established, the effect sizes are rather modest [2, 5]. This means that the average worker with CMPC will benefit somewhat from vocational rehabilitation, but there is a large variety of results: from no benefit at all to complete recovery of work outcomes. Theoretically, average effect sizes should increase when workers who will not benefit from these programs will not be offered such a program or should be offered a different program that will provide better results. This requires reliable and valid screening tools that would be able to differentiate between (groups of) workers, but these tools are presently not available.

Multidisciplinary vocational rehabilitation programs are delivered in many different shapes and forms. Literature describes a huge variety of content, disciplines, and dosage, and the optimum components for each individual worker are currently unknown. It is currently regarded as one of the main scientific challenges in this field. It requires a set of diagnostic instruments that can validly distinguish subgroups of workers in need of specific content (“what works for whom”). Perhaps because of the absence of these instruments, many vocational rehabilitation programs contain a more or less standard mix of content (mostly consisting of physical exercises, cognitive behavioral therapy or principles, education, graded activities) delivered by more or less standard disciplines (physical therapy, occupational therapy, psychology), with durations of vocational rehabilitation varying from a few hours/weeks to 100 h or more delivered over several months [7]. Theoretically, content, disciplines, and dosage that add nothing to the results can be removed from these programs, leading to similar effectiveness and improved cost-effectiveness. At this point, strong evidence-based recommendations for specific content [6] or dosage [7] cannot be given.

Even though detailed recommendations about effective components of vocational rehabilitation cannot be given, effective principles of vocational rehabilitation can be derived from literature. Realizing that differences between jurisdictions with all its different barriers and facilitators do exist, these principles can be used to tailor vocational rehabilitation programs to the needs of the individual worker and within the context of work. An overarching principle is that it depends on work-focused healthcare and accommodating workplaces. To make a real and lasting difference, both need to be addressed and coordinated. The main principles are [8] the presence of a return to work (RTW) coordinator, the principle of graded activity and graded exposure to work including modified work, and a biopsychosocial orientation of the vocational rehabilitation team.

Many vocational rehabilitation programs may benefit from a separate discipline or the so-called RTW coordinator or case manager. This person may serve as liaison between the worker, work, healthcare, benefits office, and others. The effectiveness of communication between healthcare and the workplace has been established [3]. The role of RTW coordinator as key to the program’s success and the competencies of the RTW coordinator may be more important than professional background. For this relatively new role in vocational rehabilitation for workers with CMPC, ten groups of essential competencies were established: individual traits/qualities, relevant knowledge base, RTW focus and attitude, organizational/administrative skills, assessment skills, communication skills, interpersonal relationship skills, conflict resolution skills, problem-solving skills, and RTW facilitation skills [9]. To facilitate work participation of the worker with CMPC, these competencies should be mustered to create and maintain one plan/goal for all stakeholders and keep all “aboard” along the process.

The second principle for vocational rehabilitation is that of graded activity and graded exposure to work, including modified work. During vocational rehabilitation, the worker should increase activities according to a schedule that the worker and the vocational rehabilitation team codevelop. This plan involves a gradual progressing of activities, regardless of daily fluctuations in pain intensity. “Activities” may involve exercise, physical activities, and sports activities but also work-related activities. Preferably, if jurisdictions allow for this, this should involve modified work [3]. Modifications can be duties, tasks, hours, days, etc., preferably based on shared decision by the worker and supervisor, guided by the RTW coordinator [10]. If modified work is not an option, vocational rehabilitation programs may involve simulated work activities performed at the rehabilitation clinic. These simulated work activities should follow the same principles of codevelopment and gradual increase of workload toward a predefined endpoint.

As a general principle, the vocational rehabilitation team and its members should embrace the biopsychosocial model to guide their functional diagnostic and treatment approach [2]. One of the key principles of vocational rehabilitation is to address dysfunctional beliefs and behavior. There is extensive clinical evidence that symptoms may originate from a health condition, but the development of chronic symptoms and disability also depends on psychosocial factors. There is now broad agreement that understanding and management of human illness and disability (particularly that associated with common health problems such as CMPC) must take account of biological, psychological, and social dimensions – a biopsychosocial model. It is an individual-centered model that considers the person, their health problem, and their social context: biological refers to the physical or mental health condition; psychological recognizes that personal/psychological factors also influence functioning; social recognizes the importance of the social context, pressures, and constraints on illness behavior and functioning. These elements are often described and dealt with separately. In reality, functioning depends on complex interactions between the individual, the health condition, and the environment in a dynamic social process over time [11].

The vocational rehabilitation team and its members should be regarded as one of the environmental factors that may positively influence the course of work disability. However, the opposite may also be the case. The attitude of healthcare professional may also be very relevant, as healthcare professionals can actually form a barrier for making progress in RTW. Workers are sick listed more often and longer when they have physicians who themselves hold fear-avoidant attitudes toward activities and work [12]. There is strong evidence that healthcare professionals who hold high fear-avoidance beliefs are associated with high fear-avoidance beliefs of their patients (suggesting a carry-over effect), and moderate-quality evidence that high fear-avoidant healthcare professionals more frequently advise to limit activities and work and increased sickness certification [13]. Additionally, healthcare professionals with a biomedical orientation (versus a biopsychosocial orientation) tend to nonadhere to clinical practice guidelines more often and to advise to limit activities and work more frequently [13]. It is of importance that healthcare professional should assess their fear-avoidance beliefs before exposing themselves to workers with CMPC [14].