THE SENSITIVITY AND SPECIFICITY OF PAIN RESPONSE TO ACTIVITY AND POSITION IN CATEGORIZING PATIENTS WITH LOW-BACK-PAIN

Background and Purpose. The purposes of this study were to develop scr eening tests for four low back pain (LBP) diagnoses based on patient r eports concerning the severity of pain in various positions and during activities and then to examine tile accuracy of these tests in assign ing subjects to one of four LBP diagnostic categories. The accuracy of screening tests is determined hv calculating sensitivity and specific ity and is well established in epidemiology. Subjects. One hundred six consecutive patients two either were being treated for LBP for tile f irst time or had not received medical care for LBP? at the participati ng clinics within the 12 months prior to the study were recruited. Met hods. Subjects completed a Pain Response to Activity and Position Ques tionnaire at the time of their initial clinic visit. The diagnosis of LBP was obtained fr-sm the medical record after at least 1 month of fo llow-up and the completion of diagnostic testing. Data analysis yielde d symptom clusters that were used to produce screening tests for each of the four categories of LBP. Results. Sensitivity, specificity, and positive and negative predictive power of the screening tests were (1) back disease:.57,.71,.40, and .82, (2) disk disease:.65,.49,.35, and .77, (3) spinal stenosis:.52,.74,.36, and .85, and (4) disk disease wi th spinal stenosis:.81,.54,.24, and .94. Conclusion and Discussion. Al though more than half of the subjects with a particular LBP diagnosis tested positive for that diagnosis, approximately two thirds of the su bjects who tested positive for each of the diagnoses actually had anot her diagnosis. Negative tests may be more useful in that between 77% a nd 94% of the subjects without the diagnosis tested negative. Although patient reports of LBP response to position and activity are not suff icient for diagnosis, they may be useful in ruling out a particular di agnosis.