Promoting work ability in a structured national rehabilitation program in patients with musculoskeletal disorders: outcomes and predictors in a prospective cohort study

In Sweden, the responsibility for providing health care is decentralised to the county councils. Both public and private health care providers have the same tax-based financing system and apart from a small co-pay the residents are entitled to free health care. Skåne County (Region Skåne) is the southernmost part of Sweden with a population of 1.3 million inhabitants, which correspond to 1/8 of the total Swedish population and is representative for the whole Swedish population, in terms of demographics. The Skåne Health Care Register (SHCR) contains routinely collected data of all health care in the region. All data is on an individual level, coded by personal identification number (PIN), a unique number automatically assigned to all residents. In this study, data collection took place in a natural setting at different PHC centres in the county; both private and public. Patients with MSD, seeking PHC were offered MMR, through the national rehabilitation program and were followed with self-administered questionnaires at MMR start and after finished MMR. A three month follow-up was also conducted. A questionnaire, completed by health care professionals, was answered at MMR start and after completed MMR. Also basic demographic data was collected and each patient consultation was registered with date, type of treatment and profession. The parameters were consecutively reported from different health care providers. These registrations were linked to economical compensations for the PHC centres and also for the purpose of provide follow-ups for the responsible authority and to the particular health care unit.

In Sweden, sick leave insurances include the whole working population from the age of 16 or older, and are tax-financed from day 15. Sick leave data was obtained from the Swedish Social Insurance Agency (SSIA) (Figure 1).

The setting of patients was a pre-defined cohort of all patients that had been consecutively notified for MMR in Skåne County, during September 2009 and until August 2010. The cohort included 724 patients with MSD. This is the first cohort of patients that had access to MMR through the national rehabilitation program [10]. In line with the intention of the intervention, patients receiving at least six treatments for a period of at least six weeks were included, which resulted in 637 patients. To be able to link sick leave data to patient data, all patients were sent a letter of consent with opt-out opportunity. In total 43 patients decided not to participate. Sick leave data from SSIA were linked for the remaining 594 patients. Five patients not registered in Region Skåne, one year before MMR start, were excluded. To stay close to the intention of the National rehabilitation program, patients that had a rehabilitation period lasting for more than 26 weeks were excluded and also those patients that had invalid time series for date registrations. The final study cohort consisted of 406 patients (Figure 2).

MMR comprised of evidence-based assessments and rehabilitation interventions [10]. At least three different professionals must be included in the team, whereof one had to be a physician. The interventions must last for minimum six weeks, two-three times a week and should be coordinated.

This study has been approved by the Regional Ethical Review Board in Lund Dnr 2011/169 and approved by Skåne County health care authorities was also received.

The study cohort (n = 406) consisted of 20.2% men and 79.8% women, with a mean age of 45.1 (SD 9.83) (Table 1). Patients with no SLDP the year before MMR, were slightly younger than patients with part-time SLDP (p = 0.004) and patients with full-time SLDP (p < 0.000). The group with no SLDP had higher education level compared to the group with part-time SLDP (p = 0.007) and the group with full-time SLDP (p < 0.001). Patients with full-time SLDP the year before MMR were to a greater extent not employed/self-employed (75.4%), than both the other groups (p < 0.000). These patients were also to a higher extent born outside Sweden compared to no SLDP (p = 0.001) and those with part-time SLDP (p = 0.016).

There were no differences in how symptoms were distributed when comparing the three groups based on SLDP, but there were gender differences. Most women had myalgia or pain (49.4%) whilst for men, back pain and myalgia or pain were most common and equally distributed (36.1% each).

At MMR start, 6.4% of the whole group was on sick leave in prevention, as they were part of rehabilitation for purpose of preventing future sick leave or shortening an on-going sick leave spell. 36.7% were on SL, 25.4% had DP and 44.1% had no SLDP. The total burden of SL and DP for each person, one year before MMR, was mean144 net days (SD 141.50), where 73.4 net days (SD 73.37) corresponded to SL and 70.6 (SD 12.47) net days to DP. No gender differences were noted.

The original cohort comprised of 724 patients and 318 patients were excluded from the cohort, (Figure 2) of which 22.6% were men and 77.4% women. Mean age was 45.0 years (SD 10.73), which is in line with the final study cohort. Register data on sick-leave was not available for the pre-defined original cohort.

The patients had a MMR period of mean 94.3 days (SD 38.76) and had mean 17.4 treatments (SD 7.13). The group with no SLDP had just over two visits fewer compared to the group with part-time SLDP (p = 0.005) and full-time SLDP (p = 0.011). Physicians (40.8%) and physiotherapists (34.4%) were the most common professionals when registering for MMR and also discharging MMR (43.6% resp. 33.5%). Also other health care professionals as psychologists and occupational therapists were involved in MMR but physiotherapists were the most frequently occurring health care professional. Three or more different health care professionals were involved in 62% of the patients’ rehabilitation.

EQ-5D at MMR start, after completed MMR and at follow-up differed between the groups with no, part-time and full-time SLDP (Figure 3). There were significant improvements between MMR start and completed MMR within all three groups and for the group with part-time SLDP, there was a slight improvement between completed MMR and follow-up (p = 0.035). The group with no SLDP improved more between MMR start and completed MMR compared to the group with part-time SLDP (p = 0.044) and also full-time SLDP (p = 0.044). No differences in improvement, between the three groups were seen between completed MMR and three month follow-up.

All functions were assessed as improved between MMR start and completed MMR, for all three groups (Table 2). There were differences in pain at MMR start, between the group with no and full-time SLDP (p < 0.000). Also at completed MMR there were differences in pain between no and part-time SLDP (p < 0.000) and no and full-time SLDP (p < 0.000). There were differences in improvement between the three groups (p< 0.000).

Exercise tolerance functions were different when comparing no and full-time SLDP, both at MMR start (p = 0.005) and completed MMR (p < 0.000). Also when comparing the group with no and part-time SLDP, exercise tolerance functions were different at completed MMR (p < 0.000). There were also differences between the group with part-time and full-time SLDP (p = 0.001). There were no differences between the three groups, in improvement of exercise tolerance functions (p= 0.054).

Mobility of joints functions were different when comparing the group with no SLDP and full-time SLDP at MMR start (p = 0.001) and at completed MMR (p < 0.000). At MMR start, there were also differences between no and part-time SLDP (p = 0.001). There were differences in improvement between the three groups (p= 0.037).

Comparisons were made between patients with EQ-5D < 0.5 respectively ≥ 0.5, at MMR start. There were no differences in net SL days four months before MMR start, but the group with EQ-5D < 0.5 had more net SL days at +/− two weeks from MMR start t (p = 0.002) and four month after MMR start (p = 0.003). Also, there were differences between the groups, in how net SL days developed for the period month four before MMR until MMR start (p = 0.037) and also for the whole period (p = 0.057) (Figure 4). In the group with EQ-5D ≥ 0.5, net SL days decreased with mean 0.5 days (SD10.28) under the period from month four before MMR start until four month after MMR start (p = 0.552) and in the group with EQ-5D < 0.5 net SL days increased with mean 1.5 days (SD 10.08 ) (p = 0.019).

In all three groups (no, part-time or full-time SLDP) patients reported work ability limitations at MMR start, 73.6, 76.2 and 61.1% respectively (Figure 5). When comparing the three groups, there were no significant differences in work ability limitations at MMR start. After completed MMR, there were differences between the groups. In the group with no SLDP, 34.1% reported work ability limitations, compared to 56.9% in the group with part-time SLDP (p = 0.001) and 61.1% in the group with full-time SLDP (p = 0.032). When comparing the group with part-time and full-time SLDP, no differences were seen at completed MMR (p = 0.736). At follow-up, 35.5% in the group with no SLDP reported work ability limitations, compared to 58.6% of those with part-time SLDP (p = 0.001) and 66.7% of those with full-time SLDP (p = 0.022), but no differences were seen between part-time and full-time SLDP (p = 0.544).

In the crude model, functional limitations at MMR start and completed MMR were associated with EQ-5D < 0.5. Full SLDP the year before MMR and background factors, such as not being born in Sweden and being un-employed was also associated with EQ-5D < 0.5. University education was significantly associated with EQ-5D ≥ 0.5.

In model I (R² = 0.19) more severe sensation of pain at completed MMR, moderate and more severe problems with exercise tolerance functions at MMR start were significantly associated with having an EQ-5D < 0.5 at three month follow up.

In the final, adjusted model II (R² = 0.28) more severe sensation of pain at completed MMR (OR 0.2, CI 0.1–0.5, p < 0.000), moderate (OR 0.5, CI 0.3–0.9, p = 0.032) and more severe (OR 0.4, CI 0.2–0.8, p = 0.012) problems with exercise tolerance functions, being on full-time SLDP the year before MMR (OR 0.4, CI 0.2–0.9, p = 0.027), not being born in Sweden (OR 0.4, CI 0.2–0.6, p < 0.000) were significantly associated with an EQ-5D < 0.5 at three month follow-up. Being older than 40 years (OR 1.8, CI 1.1–3.1, p = 0.026) was significantly associated with having an EQ-5D ≥ 0.5 at three month follow-up (Table 3).

In the crude model, different functional limitations both at MMR start and completed MMR, and also previous SLDP-episodes were associated with sick leave at month four. EQ-5D ≥ 0.5 at MMR start and at completed MMR were both associated with not being on SL month four after MMR (Table 4).

In model I (R² = 0.14), moderate problems with exercise tolerance functions at completed MMR, moderate and more severe problems with mobility in joints functions at completed MMR were associated with being on SL month four after MMR.

In the final, adjusted model II (R² = 0.31), moderate problems with exercise tolerance functions (OR 2.2, CI 1.2–4.0, p = 0.009) at completed MMR, more severe problems with mobility in joints functions at completed MMR (OR 2.6, CI 1.2–5.8, p = 0.015), one (OR 5.0, CI 2.6–9.8, p < 0.000) or more than one (OR 7.9, CI 3.9–15.9, p < 0.000) SLDP-episode were associated with being on SL month four after MMR start. Being > 40 years was associated with not being on SL (OR 0.5, CI 0.3–0.9, p = 0.028) and having an EQ-5D ≥ 0.5 at MMR start was not significantly associated with not being on sick leave at month four after MMR, but with a low p- value (OR 0.6, CI 0.3–1.0, p = 0.061) (Table 4).

Focus for the National rehabilitation program was to promote work ability. In this study 73.6% of the patients who were not on SLDP the year before MMR rated work ability as limited at MMR start. After MMR in this group only 34.1% reported work ability limitations. The results in this study indicate that MMR is effective also for patients not on SL and we believe that it is important to focus on patients who perceive work ability limitations but are not at SL. Often, work ability limitations are compared to being on sick leave or disability pension, but there are no perfect matches between sick leave and work ability limitations [38]. Being older than 40 years (both males and females) in our study was associated with not being on sick leave four month after MMR which was unexpected as function and HRQoL is expected to decrease in higher age. Earlier studies have indicated that older women have better quality of life [39], but population surveys indicate that EQ-5D decreases with age [32]. It is important to take into account for older persons their need for rehabilitation, since today they are expected to work at higher age and are a requested resource in society. In this study, levels of education or gender did not influence SL at month four after MMR or EQ-5D at three month follow-up but previous studies indicate that low education has an impact on RTW [40].

Function, HRQoL and work ability and sick leave were used as patient reported out-comes in this study. At MMR start, more than half of the patients had EQ-5D < 0.5. In general, EQ-5D improved during MMR, but still patients in this study had low EQ-5Ds and did not reach the level for a Swedish normal population [31, 32]. The group with no SLDP the year before MMR start was at completed MMR close to a suggested cut-off value for having work ability [41]. Having an EQ-5D ≥ 0.5 at MMR start, was not significantly associated with not being on sick leave at month four after MMR start but previous studies indicate that EQ-5D can predict RTW for patients with neck/back pain, on sick leave for > 28 days [41] and we suggest that EQ-5D can be used as a predictor of future sick leave and when planning rehabilitation.

Having SLDP the year before MMR, was associated with having an EQ-5D < 0.5 at three month follow-up. In this study the group with no SLDP the year before MMR differentiate, but in an RCT, Shiri et al. [42] found that part-time sick leave at an early stage, may be advantageous to improve perceived HRQoL. SLDP-episodes the year before MMR was associated with being on sick-leave at month four after MMR start. This indicates that SLDP-history is important information, when planning for rehabilitation and sick leave and we believe that it is easy for patients to remember if they have had any previous SLDP-episodes. Earlier studies support that SLDP is a predictor for RTW [40, 43].

An ICF-based structure is recommended when reporting about different health states in relation to MSD [44] but there is need for an improved operationalisation of the ICF, to obtain a more solid reliability [45]. In this study, three different functions were assessed. In general, functions improved after MMR. Functional limitations at completed MMR were associated with SL month four after MMR. This is in line with how work ability and the need for sick leave should be assessed in Sweden; not based on the diagnosis rather if there are functional limitations that affect work ability. What we do not know is how these functional limitations are related to the patient’s actual work demands [18, 19]. Lydell et al. [43] has found that functional capacity, among other factors, was a predictor of long-term RTW. Planning for using assessments involving such predictors, may be beneficial in planning a sick leave period, at an early stage.

A major strength in this study is that the final cohort was drawn from a cohort of all patients that were directed to MMR in Skåne County, which is a region that is representative for the whole Swedish population, in terms of demographics. Data is continuously ascertained from different PHC centres, which all used the same questionnaires and were automatically transferred to SHCR. At the time for this study, no matched controls were available.

In this study, EQ-5D was applied, which is widely used and has been found to have a good prediction of RTW for sick-listed patients with neck/back pain [41]. No Swedish tariff for EQ-5D is today available and mainly a British tariff is used [31‐33] but recently, a Danish tariff has been introduced [46]. A concern would be that the UK tariffs and the potential tariffs for Swedish data differ. In 2011, a new version, offering five levels of answering alternatives, was introduced [47].

The question about self-rated work ability was answered by those who were employed/self-employed. This is especially significant in the group with full-time SLDP, where 75.4% were un-employed at MMR start. Previous studies show that self-reported work ability, give reliable information concerning patients work ability and can predict future sick leave [48, 49] and a sustainable RTW [50]. We suggest that the single-item question from Work Ability Index (WAI) should be used.