Cross-validation of the SCL-27: a short psychometric screening instrument for chronic pain patients

We constructed a short multidimensional screening instrument for chronic pain patients based on the items contained in the Symptom Check List-90-Revised (SCL-90-R). The proposed dimensional structure of the SCL-90-R was recently shown to be irreproducible in chronic pain patients. As a consequence, the use of the Global Severity Index (GSI) was recommended, although it did not capture all information contained in the many items of the SCL-90-R. Based on an exploratory factor analysis, a six-dimensional structure using 27 items from the SCL-90-R was explored utilizing the data of 2780 chronic pain patients. A short form was prospectively tested on 581 patients in the same setting. Criteria for item selection were high convergent and low discriminant correlations. The assessment of the dimensions was kept short, but a minimum of four items were retained. A questionnaire yielding the dimensions (I) depressive symptoms, (II) dysthymic symptoms, (III) vegetative symptoms, (IV) agoraphobic symptoms, (V) symptoms of social phobia, and (VI) symptoms of mistrust was obtained. Additionally, the GSI of the SCL-90-R could be estimated precisely (r =0.96). The SCL-27 can be used for screening psychopathology in chronic pain patients. The scoring algorithm of the SCL-27 can be used for the 90-item form as well.