Background
With 12-month prevalence rates of more than 75% [
1], back pain is one of the main health problems in German adults [
2]. National health surveys indicate that 25% of women and 17% of men reported experiencing chronic back pain (CBP), i.e. back pain almost every day for at least 3 months, during the last 12 months [
3]. Back pain is more prevalent in women, in older people and in people with less education [
1,
3]. Use of health care services, sickness absence, and disability pension payments mean that illness has a high cost [
2].
The World Health Organisation (WHO) deemed rehabilitation essential to enabling people with disabilities or chronic diseases to participate in work and society, but also identified unmet needs [
4]. In Germany, age standardised utilisation of medical rehabilitation for musculoskeletal disorders decreased over the 14-year period between 2001 and 2015 from 11.9 per 1000 to 8.7 per 1000 in men and from 10.6 per 1000 to 7.7 per 1000 in women. Moreover, the proportion of disability pensioners with musculoskeletal disorders who did not undergo medical rehabilitation before their disability pension was granted increased over the 5-year period between 2007 and 2012 (males: 47.5 to 48.3%; females: 41.0 to 45.0%) [
5,
6].
Previous international research studies have reported various barriers to using rehabilitation services, i.e. factors that prevent persons from using rehabilitation services despite an obvious need for them. For example, a systematic review [
7] identified a range of financial, structural, personal and attitudinal determinants of access to rehabilitation services in the United States, but it is questionable whether these findings would transfer to the German context. In Germany, rehabilitation for working-age people is provided mainly by the German Pension Insurance (GPI). The GPI is a compulsory pension insurance scheme. Workers contribute to a pension scheme which is administered by the GPI. If workers reach the age of 65 years (gradually increasing to 67 years by 2031), the GPI pays a monthly pension based on their pension contributions. People who have a permanent disability that prevents them from working receive a disability pension until they become eligible for an old age pension. The GPI provides rehabilitation services on the principle ‘rehabilitation before pension’, i.e. they aim at avoiding paying disability pensions. The GPI offers about one million rehabilitation programmes per annum. Usually the prerequisite for access to rehabilitation is a claim by the person in question. The claim will be appraised by the GPI to determine the need for rehabilitation. Only post-acute rehabilitation (about one third of all rehabilitation measures) makes a simplified procedure for gaining access to medical rehabilitation possible.
During the last two decades, a number of studies have attempted to address the problem of unmet rehabilitation needs in Germany, either by asking people eligible for rehabilitation services or important stakeholders about barriers to using them [
8‐
13] or by comparing users and non-users to identify determinants of rehabilitation utilisation [
13‐
19]. According to these studies, the main predictor of rehabilitation utilisation appears to be impaired health, manifested as poor subjective health [
8,
11,
14‐
17], functional impairment or impairment in activities of everyday life [
11,
19], chronic conditions [
11,
19], poor work ability [
11,
18], long sickness absence [
8,
11,
14,
19], and greater use of medical care services [
11,
14]. Though these findings indicate that use of medical rehabilitation services is linked to substantial health problems affecting work ability, they do not give insight into the barriers to using rehabilitation services. Other studies have found that subjective rehabilitation need, rehabilitation intention and plans for utilising rehabilitation services predicted use of services [
17]. These variables may be proxy measures for the level of information about rehabilitation services and thus lack of awareness may represent a barrier to use of services. This suggestion is supported by the finding that the probability that an individual would request rehabilitation services was increased by a higher self-efficacy, i.e. the belief of being able to apply for a medical rehabilitation [
17]. Further cross-sectional findings also indicate the relevance of self-rated job insecurity [
8,
9,
11,
13], the recommendation of the attending physician [
8,
10‐
12,
17,
20] and perceived family support [
10‐
12,
17,
20]. Positive attitudes toward rehabilitation services were more salient in former rehabilitants or persons who planned to participate in a rehabilitation programme in the near future [
8,
11,
19,
20]. Previous research studies have produced inconsistent findings on the roles of sex, age, and socio-economic background in the use of rehabilitation services [
8,
11,
13‐
15,
20]. In the case of people with CBP intention to use and actual use of rehabilitation services may be influenced by job situation, work conditions, conflict between work and family roles and coping strategies, but so far these potential barriers have not been investigated through longitudinal research. Our first research goal is therefore to analyse a comprehensive set of barriers to accessing rehabilitation via a prospective design, using a sample large enough to provide a clear picture of the determinants of use of medical rehabilitation services.
The second research goal relates to the effectiveness of rehabilitation services. Attending physicians, who are important stakeholders when requesting medical rehabilitation, should base their advice about medical rehabilitation on the best current evidence [
21]. Although international research has shown that multimodal medical rehabilitation has a beneficial impact on various outcomes (work ability, pain, quality of life, participation) [
22‐
27], the setting and context of these studies were different from the 3-week inpatient rehabilitation programmes that are usual in Germany and so a separate evidence base is needed to demonstrate the effectiveness of German rehabilitation programmes. However, evidence on the health-related effects of German medical rehabilitation programmes for patients with CBP is, at best, contradictory [
28,
29]. A previous small, single-centre randomised controlled trial tested the efficacy of medical rehabilitation in patients with CBP using a waiting list control group. Jäckel et al. [
30] found short-term effects (4-week follow-up) on pain, anxiety and depression. The design did not enable testing of long-term effects. A more recent randomised controlled trial by Hüppe et al. [
31] used a smart approach in which patients suffering from chronic musculoskeletal disorders who had impairments indicative of a need for rehabilitation had been actively supported to request for rehabilitation services. Within 6 months of study entry, 69% of the intervention participants, but only 20% of the controls, participated in a 3-week inpatient rehabilitation programme, but there were no group differences in any of the primary and secondary outcomes at the 6- and 12-month follow-ups. It should be noted, however, that the effects of rehabilitation were tested in a population that only opted to pursue rehabilitation after receiving additional support and counselling designed to encourage them to do so. Lower grade evidence for the effectiveness of rehabilitation is available from case series (observational studies without controls). These studies reveal minor to moderate improvements in several outcomes [
32,
33]. However, the randomised controlled trial by Hüppe et al. [
31] indicated that comparable patients who do not use rehabilitation services might show similar improvements. Whilst these findings might justify restricting access to medical rehabilitation, remarkable efforts have been made to improve rehabilitation services over the last several years. These include the development of evidence-based therapy standards designed to improve the quality of multi-professional treatment and the provision of active therapies [
34], implementation of modern patient education interventions [
35,
36], the development of work-related medical rehabilitation [
37‐
40], and more emphasis on aftercare and follow-up sessions to maintain behaviour and attitude changes [
41,
42]. Randomised controlled trials and controlled clinical trials have shown that these modifications do improve outcomes compared to conventional medical rehabilitation.
According to the demands of evidence-based medicine, the lack of evidence may itself be a major barrier to the utilisation of rehabilitation services. It follows that to justify increased utilisation of rehabilitation services in the future we need high-quality investigations into the effectiveness of rehabilitation services. From a health service research perspective there needs to be a focus on rehabilitation under real-life conditions and its long-term effects through comparisons with patients who do not receive rehabilitation services. Large-scale, randomised controlled trials with long-term follow-up periods are not feasible due to the legal foundations of rehabilitation, so appraisals of the outcomes of medical rehabilitation must be based on data from cohort studies. To our knowledge, this study is the first attempt to investigate the effects of German medical rehabilitation services for persons with CBP, under routine conditions and via a large cohort study using propensity score matching.
The study protocol has been prepared according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) checklist [
43].