The reliability of nonorganic sign-testing and the Waddell score in patients with chronic low back pain

STUDY DESIGN. An observational prospective cohort study. OBJECTIVES. To determine the reliability of nonorganic sign-testing in patients with chronic low back pain (CLBP), and to identify determinants of diagnostic disagreement. SUMMARY OF BACKGROUND DATA. For the assessment of behavioral responses to examination, Waddell et al published "the Waddell score" in 1980. The Waddell score consists of 8 nonorganic signs, divided into 5 categories. The overall score is positive if at least 3 of the categories are scored positive. Although the Waddell score is widely used, little is known about its reliability. METHODS. Two observers examined 126 consecutive patients with CLBP referred for rehabilitation. Cohen's κ was used to compute the interobserver and intraobserver reliability of the sign maneuvers, categories and Waddell score. Cronbach's α was calculated for the 5 categories and 8 signs to determine internal consistency. χ tests were applied to determine the possible influence of clinical characteristics on interobserver reliability. RESULTS. Interobserver reliability varied from 0.33 to 0.74 for the sign maneuvers and categories, and was 0.48 and 0.49 for the overall Waddell score. Intraobserver reliability varied from 0.43 to 0.84 for the sign maneuvers and categories, and was 0.65 and 0.68 for the overall Waddell score. Internal consistency varied from 0.65 to 0.72 for the categories and from 0.71 to 0.78 for the signs. Determinants of diagnostic disagreement did not exceed levels of significance (P < 0.05). CONCLUSION. For trained observers of a population of patients with CLBP in a rehabilitation setting, the interobserver reliability of the Waddell score was moderate and the intraobserver reliability was good. No influence of clinical characteristics was found on interobserver reliability. To optimize the homogeneity and variability of the Waddell score, we recommend summing up the individual signs instead of summing up the categories. © 2008 Lippincott Williams & Wilkins, Inc

Identification of patients with chronic low back pain who might benefit from additional psychological assessment

Objectives: To identify signs and symptoms that should alert clinicians to the need for additional psychological assessment in patients with chronic low back pain (CLBP). Methods: In this prospective cohort study, 229 consecutive patients with CLBP who attended an outpatient rehabilitation center were assessed by psychologists and physical therapists before their treatment started. The signs and symptoms assessed by the physical therapists were compared with the assessments made by the psychologists, which were considered to be the reference standard (relevant psychological disturbances, yes or no). Univariable and multivariable regression methods were applied to investigate which signs and symptoms were associated with the reference standard. A receiver operator characteristic (ROC) curve was constructed to assess the overall accuracy of the final model. Results: The psychologists classified 53% of the patients as having relevant psychological disturbances. Univariable analysis revealed statistically significant differences (P<0.05) between the 2 patient groups (relevant psychological disturbances, yes or no) for 10 of the 17 signs and symptoms. Multivariate analysis yielded a screening instrument consisting of the following 4 signs and symptoms: presence of Waddell signs, elevated scores on the pain drawing, absence of a directional preference, and daily use of analgesic medication for CLBP [area under the ROC curve, 0.81 (95% confidence interval: 0.75, 0.87)]. Discussion: This study established a clinically useful screening instrument for the identification of patients with CLBP who might benefit from additional psychological assessment in an outpatient rehabilitation setting. Further research is needed to confirm our preliminary results. Copyright © 2011 by Lippincott Williams & Wilkins