Construct validity of practical questionnaires for assessing disability of low-back pain

Four practical questionnaires used for assessing disability associated with chronic low-back pain were investigated. Comparison of findings among 93 patients disclosed a moderate level of agreement (r = 0.44-0.63) between the scales, providing limited evidence that a single construct is being measured by each. The questionnaires were more strongly related to each other than to psychosocial scales, which suggests that findings are distinguishable from distress. However, higher distress was significantly associated with greater reports of disability. This was most discernible in the form of more enduring characteristics that may reflect neuroticism. These findings allow modest support for the construct validity of the four questionnaires and suggest a need for caution with their use because persistently negative affect may be a biasing factor.