Systematic review of risk factors for back disorders

Introduction and objective The purpose of this systematic review is the identification of work-related risk factors for the occurrence of back disorders. Several reviews on this topic have been published so far. However, none of these included clearly stated in- and exclusion criteria as well as a methodological quality assessment of the studies. Material and method The available literature was selected in an automatic search of the data bases Medline, Embase, Psyclit, NIOSHTIC, CISDOC, HSELINE and Sportdiscus. The abstracts of all the citations were retrieved and examined. Studies had to meet the following criteria to be included in this review: 1) The design was case-control, prospective or retrospective cohort; 2) The population was a working or a community-based population; 3) The out­come measure was based on symptoms or signs of non-specific low back pain or sciatica. The selected publications are independently scored by two reviewers according to a set of methodological criteria regarding informativeness, validity and precision. The criteria concern the purpose and population of the study, exposure and outcome measurements, analysis and data presentation. Two different criteria lists are used for case-control and cohort studies. These lists were adapted from criteria lists used in systematic reviews of RCT's on treatment. The reviewers rate each methodological criterion positive, negative or unknown based on the information presented. Each study is assigned a total methods score by summing up all the positive validity criteria. The relationship between a potential risk factor and the outcome is considered positive in case of a statistically significant association, negative in case of no association and incon­clusive in case of no association, but insufficient power of the study at issue. Furthermore, the magnitude of the odds ratio's and relative risks found, are compared and summarized, taking into consideration the methodological quality of the available studies. Results The literature search based on information provided in the different data bases resulted in the identification of 173 publications, mostly in English. However, this selection includes references with too little information to make a final decision about in- or exclusion. The next step will be a further selection based on the information in the full papers. At the conference the final results will be presented, including the methodological quality assessment and the overview of the strength of the evidence for each risk factor identified.