title: The use of nonorganic signs and symptoms as a screening tool for return-to-work in patients with acute low back pain.
abstract: METHODS
  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 in patients with acute, work-related low back pain and to calculate the predictive validity of the signs and symptoms, alone and in combination, using an outcome of return to work within 4 weeks of initiating treatment.
  
  
  BACKGROUND
  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.
authors.affiliation: Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Fritz
authors.forename: R S
authors.initials: RS
authors.lastname: Wainner
authors.forename: G E
authors.initials: GE
authors.lastname: Hicks
mesh_terms: D000208:Acute Disease; D000328:Adult; D004185:Disability Evaluation; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008137:Longitudinal Studies; D017116:Low Back Pain / Q000175:diagnosis* / Q000534:rehabilitation; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis* / Q000534:rehabilitation; D026741:Physical Therapy Modalities; D011237:Predictive Value of Tests; D012372:ROC Curve