A Cochrane review included nine RCTs (20 101 employees) and nine cohort studies (1280 employees). Studies compared training to no intervention (4), professional education (2), a video (3), use of a back belt (3) or exercise (2). Other studies compared training plus lifting aids to no intervention (3) and to training only (1). The intensity of training ranged from a single educational session to very extensive personal biofeedback. Six RCTs had a high risk of bias. None of the included studies showed evidence of a preventive effect of training on back pain. There was moderate quality evidence from seven RCTs (19,317 employees) that those who received training reported levels of back pain similar to those who received no intervention, with an odds ratio of 1.17 (95% confidence intervals (CI) 0.68 to 2.02) or minor advice (video), with a relative risk of 0.93 (95% CI 0.69 to 1.25). Confidence intervals around the effect estimates were still wide due to the adjustment for the design effect of clustered studies. The results of the cohort studies were similar to those of the randomised studies.
The interventions that were used varied from one session of simple advice on lifting to training once a week for two years. In some of the studies, traditional training was supported by follow-up and feedback at the workplace. All interventions used an educational model that assumed that the information provided in the intervention would lead to a change in knowledge, attitude or skills. In addition to information, all interventions included the opportunity to practice the skills to some extent in either the educational setting or at follow-up in practice. The most frequently used outcome was back pain. This was measured as back injury rate, presence of low-back pain within a given time period, score for self-reported low-back pain, self-assessed improvement or deterioration of low-back insufficiency, as well as episodes and days with low-back pain within a given time period. Disability caused by back pain was used as an outcome in two studies. Sick leaves were followed in one study, and Oswestry Disability Index scores in the other. The follow-up times varied from six months to 5.5 years in RCTs and from eight weeks to two years in cohort studies.There is moderate quality evidence that MMH advice and training with or without assistive devices does not prevent back pain or back pain-related disability when compared to no intervention or alternative interventions. There is no evidence available from RCTs for the effectiveness of MMH advice and training or MMH assistive devices for treating back pain. More high quality studies could further reduce the remaining uncertainty.