The NICE reviewers screened >18,000 articles (identified from 22 databases and 11 websites) that were published between 1990 and 2007, retrieved 800 papers, and summarised 49 reports on sickness absence, of which 42 concerned MSDs [4
]. We retrieved all 42 of these reports. We also checked exclusions from the NICE review, from which we identified three further reports relevant to our inquiry. We re-ran NICE’s search strategy in Medline and Embase for 1st Jan 2007 to 23rd April 2010, to check for later publications; and also for 1990 to 23rd April 2010 using terms for health-related job loss, retirement and disability pensioning in lieu of sickness absence. Our searches identified two 2010 Cochrane reviews, the citations from which were also considered [6
Additionally, we checked a best evidence synthesis by Waddell et al
on vocational rehabilitation [8
]. This considered several thousand citations identified from five electronic databases, hand searching of 18 journals and the publications of 13 organisations or Government departments, internet searches, citation tracking, and the authors’ personal databases. We retrieved all cited systematic reviews, meta-analyses, and Cochrane reports covering interventions on sickness absence and job loss for MSDs (n=41), excluded nine that fell outside the scope of our inquiry, and checked the primary research reports cited in the remaining 32.
After removal of duplicates, these various sources yielded a total of 2,156 reports which were screened for eligibility.
We retained only peer-reviewed randomised controlled trials (RCTs) and cohort studies published from 1990 onwards, in which subjects were workers who had an MSD and/or were on sick leave with an MSD at entry, or had taken sick leave for an MSD in the past 12 months. We limited inclusion further to studies in which vocational outcomes of interest (sickness absence, MSD-related job loss, return to work during follow-up, or prevalence of work attendance at follow-up) could be quantified for defined worker populations. Qualifying interventions were those delivered in a primary care or workplace setting or conducted in collaboration with primary care providers or employers, excluding drug trials and surgery, but including physical therapies delivered by physiotherapists or chiropractors. Reports relating to external traumatic injury were excluded.
details the selection process in PRISMA [9
] format. From the 2,156 reports screened, we excluded 2,072 on title or abstract, and a further 30 that we retrieved and assessed in full. This left 54 reports from 42 separate studies that formed the review base.
Flow chart of the review’s identification, screening, and selection stages
Data abstraction and quality assessment
One investigator (KTP) systematically abstracted data from each study on: study populations (type of MSD, case definition, exclusion criteria, source of recruitment, setting, participant flow, numbers, baseline characteristics); outcomes; interventions (e.g. nature, timing, intensity, frequency); numbers analysed, analytical methods and treatment of losses to follow-up; effect estimates and confidence intervals or data permitting estimates of precision; and where relevant, procedures for randomisation and blinding. Data abstraction was piloted in ten reports, and then independently checked for all reports by a second investigator (CHL).
Studies were evaluated for their susceptibility to bias using, for RCTs, the Cochrane Back Review Group’s criteria [10
], and for cohort studies, a checklist adapted from those criteria. A quality score was derived for each study by assigning one point for each quality measure. For sensitivity analysis, we classified studies in thirds of the distribution of quality score.
Classification of interventions
We identified various physical, psychological, social and environmental interventions directed at (i) the individual, (ii) his/her work or workplace, or (iii) healthcare and other services to which he/she had access.
At the individual level, interventions included exercise therapy, work hardening, or physical therapy (often called a ‘functional restoration programme’); psychological therapy aimed at behavioural or attitudinal change, and general in nature (e.g. CBT, coping, relaxation) or vocationally focussed (at overcoming psychosocial barriers to working, or attitudes to and perceptions of work), often accompanied by education aimed at influencing perceptions and behaviour (e.g. ‘Back School’ education); rehearsal of safer working techniques; and use of lumbar supports.
At the workplace level, approaches included: ergonomic and/or psychosocial risk assessments – aimed at the individual (e.g. how well an exercise programme matched job demands) or at identifying and controlling workplace risks (‘participatory’ ergonomic assessments, involving the individual, his/her manager, and union); ergonomic changes to the physical environment; job modifications (e.g. lighter duties, reduced hours); and interventions directed at managers (education and advice).
At the service level, approaches included: assessment and a co-ordinated action plan, evolved by a multidisciplinary case management team or a case manager; consultation with an occupational physician; education of primary care doctors and/or occupational physicians, and/or formalised agreements between them, to improve liaison; and access to extra external support and referral services.
Some categories were capable of finer delineation e.g. exercise therapy, work hardening, or physical therapy could be subdivided into: exercises to build aerobic capacity, stamina, and endurance; exercises to build anaerobic capacity, and strength and size of muscles – e.g. strength training, weight training; resistance, static, isometric, or isotonic exercises; exercises to improve balance and co-ordination – e.g. stabilising exercises; flexibility exercises such as stretching; exercises which rehearsed work activities (to build endurance and flexibility for everyday work tasks, and mitigate fear-avoidance psychological responses); physical therapy applied by a health care professional to increase mobility or reduce pain – e.g. traction, manipulation, massage, TENS, pulsed electromagnetic therapy, ultrasound, heat/cold. Where accounts were sufficiently detailed, we used the framework of Abraham and Michie [11
] to sub-classify behavioural change interventions into component techniques such as: providing information on behaviour health-links, prompting practice, providing feedback on performance, setting graded tasks, prompting identification of barriers, providing contingent rewards, help in specific goal-setting, agreed behavioural contracts, and stress management.
Data were abstracted on three main outcomes: return to work, avoidance of health-related job loss, and mean days of sick leave/month over follow-up. The corresponding measures of effect (relative risk (RR) of return to work or job survival and mean days of sick leave/month avoided in treatment vs. comparison group for a given follow-up) were seldom reported, and had to be derived from summary data in reports – e.g. the proportions by group who had returned to work/lost a job and numbers at risk; or the mean sickness absence, standard deviation and numbers studied by group. When proportions were given but not subject numbers, we imputed numbers so that confidence intervals of RRs could be estimated. In the absence of direct author information, we made the simplifying assumption that, for skewed quantitative data on sickness absence, the sampling distribution of the difference in mean days of absence between groups was roughly normal or that violations of this assumption were trivial. Estimates of precision were made using immediate commands in the STATA package.
Preliminary tabulations highlighted substantial heterogeneity of case definitions and interventions, so we decided against combining data in meta-analyses. Instead, findings were summarised descriptively across studies as the median and interquartile range (IQR) of effect estimates, overall and by specified subject characteristics (e.g. pain site, duration of sick leave at baseline), study features (e.g. follow-up time, study size, study quality), and type of intervention. Few investigations analysed or provided raw data on cost-effectiveness. However, we estimated for each comparison the time involved in delivering the intervention, as a proxy for invested resources, and compared outcomes by invested effort. Finally, a check was made for publication bias by constructing funnel plots of the natural logs of treatment effects vs. their standard errors.