Comparison of three measures for detecting psychological disturbance in patients with low back pain.

The MMPI Low Back Scale, the 'Conversion V' MMPI profile and the Back Pain Classification Scale were compared for accuracy in detecting psychological disturbance in a sample of 91 patients with low back pain. These patients were classified as to the presence or absence of organic findings and psychological disturbance on the basis of objective and independent evaluations. Hit rates or 37.4%, 64.5% and 78.0% were produced by the 3 measures, respectively. The Back Pain Classification Scale was the most accurate measure, and the only scale to exceed base rate. The implications of these findings for clinical practice are discussed.