Risk factors for nonorganic low back pain in patients with worker's compensation.

BACKGROUND CONTEXT Nonorganic low back pain (NOLBP) is common in the worker's compensation (WC) population. Consults with specialists constitute an unnecessary cost to the system, and a means of screening for these patients is necessary. PURPOSE To design easily identifiable criteria to help identify which WC patients are likely to have nonorganic pain. STUDY DESIGN A retrospective chart review of WC patients with low back pain (LBP) seen in consultation by a single spine surgeon over a 2-year period at a university medical center. PATIENT SAMPLE One hundred twenty-seven WC patients with LBP were seen in consultation by a single spine surgeon over a 2-year period. All were referred for surgical evaluation. Potential risk factors for nonorganic pain were identified, which included alleged injury in multiple bodily areas, presence of concomitant cervical and/or thoracic complaints, initial presentation to chiropractor, mechanism of injury including slip and fall or lifting of a patient, number of previous independent medical examinations performed, presence of psychiatric diagnosis, areas of pain different from first report of injury, greater than 13 months between evaluations, occupation as a health-care employee, presence of legal representation, amount of time off work, present work status (working or disabled), and number of previous WC claims. OUTCOME MEASURES Outcome measures included the number of Waddell's signs and additional nonorganic/inconsistent pain behaviors noted during the examination by the spine specialist. Nonorganic low back pain was defined as four or more Waddell's signs or three Waddell's signs plus one additional inconsistent behavior. METHODS A stepwise logistic regression was used to determine which of the risk factors were significantly associated with nonorganic pain, correcting for age and sex. We then used an analysis of deviance to determine which combination of factors could best differentiate patients with nonorganic findings. RESULTS Factors that were significantly associated with nonorganic pain included mechanism of injury including slip and fall or lifting of a patient (odds ratio [OR]=5.7, p=.03), alleged injury in greater than two bodily areas (OR=4.2, p=.02), presence of concomitant cervical and thoracic complaints (OR=2.9, p=.04), initial presentation to chiropractor (OR=7.7, p=.01), and back pain not listed on first report of injury (OR=3.3, p=.04). Patients with three or more of these findings were found to be at a very high risk of having nonorganic pain (greater than 95%). CONCLUSIONS We found a significant association between certain easily identifiable criteria and NOLBP in a cohort of WC patients. These criteria included mechanism of injury including slip and fall or lifting of a patient, alleged injury in greater than two bodily areas, presence of concomitant cervical and/or thoracic complaints, initial presentation to chiropractor, and areas of pain different from first report of injury. More than 95% of patients with three or more of the aforementioned criteria were found to have nonorganic pain. This information may help the specialist and the WC provider identify patients at a high risk for nonorganic pain, thereby reducing unnecessary costs.