Do workplace interventions prevent low-back disorders? If so, why?: a methodologic commentary.

Abstract

The demand for workplace interventions to prevent low-back disorders has increased in recent years. At the same time, a crisis in the literature has become apparent: there are conflicting reports on whether or not these interventions work. With the aim of understanding the reason for the dissension in the literature, six studies were selected for close examination. These were studies of interventions based on differing principles, i.e. a change in organizational ethos to promote back safety, back belt use, the introduction of ergonomic devices, and back-strengthening exercises. If the studies are taken at face value, any of the interventions, regardless of type, has a tremendous effect. Methodological problems inherent in these studies may provide a clue to why essentially different interventions were found to be consistently successful. Study design quality has long been noted to exert a particular influence on the evaluation of outcomes: the quality of the study design is often inversely related to reported outcomes. Of the six studies selected for examination, four did not include a contemporaneous control group, five did not randomly assign subjects to test and control groups, and none included a placebo group. Given these research designs, variables other than those tested by the studies may have produced the reported results. These variables include 'beliefs of the intervention providers' and 'coalescence of the work group', both of which are discussed. Two approaches, the pragmatic and the explanatory, may be used to study workplace interventions to prevent low-back disorders. Most of the examined studies are pragmatically oriented. Having dealt with study design problems expeditiously, these studies may be characterized as more immediately responsive to the demand to evaluate workplace interventions than explanatory studies. On the other hand, explanatory studies, most notably associated with randomized clinical trials in medicine, are more rigorous. Enough pragmatically oriented studies have been conducted to suggest that workplace interventions may have an effect on low-back disorders. More conclusive explanatory studies may now be conducted.