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

The demand for workplace interventions to prevent low-back disorders has in creased in recent years. At the same time, a crisis in the literature has b ecome apparent: there are conflicting reports on whether or not these inter ventions work. With the aim of understanding the reason for the dissension in the literature, six studies were selected for close examination. These w ere studies of interventions based on differing principles, i.e. a change i n organizational ethos to promote back safety, back belt use, the introduct ion 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 st udy design is often inversely related to reported outcomes. Of the six stud ies selected for examination, four did not include a contemporaneous contro l 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 resul ts. These variables include 'beliefs of the intervention providers' and 'co alescence of the work group', both of which are discussed. Two approaches, the pragmatic and the explanatory, may be used to study workplace intervent ions to prevent low-back disorders. Most of the examined studies are pragma tically oriented. Having dealt with study design problems expeditiously, th ese studies may be characterized as more immediately responsive to the dema nd to evaluate workplace interventions than explanatory studies. On the oth er hand, explantory studies, most notably associated with randomized clinic al trials in medicine, are more rigorous. Enough pragmatically oriented stu dies have been conducted to suggest that workplace interventions mat. have an effect on low-back disorders. More conclusive explanatory studies may no w be conducted.