Low back pain: risk evaluation and preplacement screening.

As screening tests in a currently asymptomatic population, all of the available methods for predicting low back pain and disability have serious technical, ethical and legal limitations. From a technical point of view, none of the predictive tests appear to have sufficient sensitivity or specificity to justify routine usage. The most sensitive indicator (a past history of low back pain) lacks reliability and specificity. Muscle strength-testing may be predictive of future musculoskeletal injury as part of a well-designed program that considers specific job demands in relation to specific worker capabilities. Unfortunately, the conditions necessary for a well designed program--a large number of predictable high-risk jobs that have measurable specific demands that can be reproduced reliably in a testing situation--are rarely met. In the future, the use of computer-assisted multivariate models analogous to those used in the prediction of cardiovascular risk may be capable of integrating information about an individual's medical history, physical exam, physical capacity and other tests with specific job requirements to give us a more accurate prediction of the future risk of back pain and disability. If such predictive models are ever developed and verified, it would then be appropriate to examine various interventions and their effectiveness in modifying risks for the population and the individual worker. From a legal point of view, all of the techniques described hold potential for significant discrimination against legally protected groups. Making employment decisions with regard to a past history of low back pain or on the basis of an x-ray will lead to systematic age discrimination and discrimination against the handicapped. The use of muscle strength-testing will systematically discriminate against women and certain ethnic groups. The ethical implications of predictive screening for low back pain clearly depends on what is done with the information that is garnered from such tests. If the information is used only to make a safe job placement for an individual, and this placement does not affect the individual's salary or future job possibilities, then the testing program may have a net social value to the extent that it leads to true prevention of low back pain and disability. If the tests are used merely to reduce employer liability by refusing employment to those who are thought to be at "high risk," the technical, legal and ethical limitations will far outweigh any perceived benefits.