IS WORK STATUS OF LOW-BACK-PAIN PATIENTS BEST DESCRIBED BY AN AUTOMATED DEVICE OR BY A QUESTIONNAIRE

Study Design. A prospective cohort study of patients with subacute occ upational back pain. Objectives. To study the relation between a marke ted opto-electric device measuring trunk kinematics, a widely used spe cific functional capacity questionnaire, and work status in back pain patients, and to assess the responsiveness to change in work status of the optoelectric device and the questionnaire. Summary of Background Data. Several instruments have been developed to evaluate the function al capacities of patients with back pain, but the relation between the se instruments and work status has rarely been studied. Methods. The r elation between the opto-electric device, the questionnaire, and work status in patients with back pain was evaluated. The study population was a prospective cohort of patients with subacute back pain who were absent from regular work for more than 4 weeks. All data were compiled blindly on the same day, at study entry (4 weeks after work accident) , and at 12, 24, and 52 weeks after the work accident. The validity of the questionnaire and opto-electric device scores was assessed with p artial correlation analyses, standardized response mean, logistic regr ession analyses, and receiver operating characteristics curves. Result s. The correlation between the questionnaire and opto-electric device scores was low. The questionnaire scores were significantly related to work status, but the opto-electric device scores were not. The questi onnaire was responsive to change in work status, whereas the opto-elec tric device was not. Conclusions. The opto-electric device scores were not related to either functional capacity scores (questionnaire) or w ork status in patients with low back pain, and the opto-electric devic e was not responsive to change in work status. Conversely, the questio nnaire was related to work status and was responsive to change in work status.