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-related 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 symptoms, alone and in combination, using an outcome of f return to work within 4 weeks of initiating treatment. Summary of Background Data. Waddell et al have proposed nonorganic signs and symptoms as screening tools in patients with chronic low back pain for detecting the presence of abnormal illness behavior and identifying patients in need of further evaluation to improve the likelihood of a successful treatment outcome. Methods. Consecutive patients referred to physical therapy with work-related low back pain of less than 2 weeks' duration were examined for the presence of nonorganic signs and symptoms before initiating physical therapy treatment. The outcome measure used was the ability to return to work without restrictions within 4 weeks of the initial evaluation. Results. Sensitivity, specificity, and likelihood ratios were calculated for all possible cut-off values for the nonorganic signs, symptoms, and the nonorganic index (signs and symptoms). The best cut-off values were two or more signs (negative likelihood ratio = 0.75), three or more symptoms (negative likelihood ratio = 0.62), and an index score of three or more (negative likelihood ratio = 0.59). Area under a receiver operator characteristic curve for the signs, symptoms, and index were 0.60, 0.63, and 0.63, respectively. Conclusions, Because the nonorganic tests are purported to serve as screening tests, cut-off values were selected that minimized false-negative results. 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 returning to work after an episode of acute low back pain.