Test-retest reliability of patient reports of low back pain.

Low back pain is, in large part, a subjective illness. Clinicians must use patient descriptions of the severity and location of low back pain and how it responds to various activities and positions to make diagnostic and treatment decisions. Therefore, it is important to understand how reliably patients describe these aspects of low back pain. The purpose of this study was to determine the test-retest reliability of a visual analogue scale measure of pain intensity, a pain drawing measure of pain location, and the pain response to activity and position questionnaire. Fifty-three subjects (28 men and 25 women) with a mean age of 54.2 years were recruited from an outpatient orthopaedic clinic. They completed the visual analogue scale, pain drawing, and pain response to activity and position questionnaire before and again immediately after seeing their physician. Thirty-three subjects also completed the visual analogue scale and pain drawing measure that evening and the next morning. Test-retest reliability of the visual analogue scale and pain drawing measure was examined using an intraclass correlation coefficient. Reliability of each item on the pain response to activity and position questionnaire was examined by calculating an unweighted Cohen's kappa. Overall, the three pain measures demonstrated fair to good test-retest reliability: 1) visual analogue scale = .66-.93, 2) pain drawing = .58-.94, and 3) pain response to activity and position questionnaire = .46-.89. The results of this study suggest that, although there is some variability in how consistently patients report various aspects of low back pain, the reliability of these pain measures is sufficient to permit their use in making clinical decisions and measuring treatment outcomes.