The use of nonorganic signs and symptoms as a screening tool for return-to-work in patients with acute low back pain

Study Design. A longitudinal cohort study of patients with acute, work-rela ted low back pain undergoing physical therapy treatment. Objective. To determine cut-off values maximizing the predictive ability of the nonorganic signs and symptoms fn patients with acute, work-related low back pain and to It;calculate the predictive validity of the signs and sym ptoms, alone and in combination, using an outcome of f return to work withi n 4 weeks of initiating treatment. Summary of Background Data. Waddell et al have proposed nonorganic signs an d symptoms as screening tools in patients with chronic low back pain for de tecting the presence of abnormal illness behavior and identifying patients in need of further evaluation to improve the likelihood of a successful tre atment outcome. Methods. Consecutive patients referred to physical therapy with work-relate d low back pain of less than 2 weeks' duration were examined for the presen ce of nonorganic signs and symptoms before initiating physical therapy trea tment. The outcome measure used was the ability to return to work without r estrictions within 4 weeks of the initial evaluation. Results. Sensitivity, specificity, and likelihood ratios were calculated fo r all possible cut-off values for the nonorganic signs, symptoms, and the n onorganic index (signs and symptoms). The best cut-off values were two or m ore signs (negative likelihood ratio = 0.75), three or more symptoms (negat ive likelihood ratio = 0.62), and an index score of three or more (negative likelihood ratio = 0.59). Area under a receiver operator characteristic cu rve for the signs, symptoms, and index were 0.60, 0.63, and 0.63, respectiv ely. Conclusions, Because the nonorganic tests are purported to serve as screeni ng tests, cut-off values were selected that minimized false-negative result s. Even with optimal cut-off values, none of the nonorganic tests served as effective screening tools. Other screening tools may prove more effective for the early identification of patients at increased risk for delay in ret urning to work after an episode of acute low back pain.