Tested the accuracy of the MMPI and the FAM for predicting appropriate vs. inappropriate disability (illness behavior) in low back pain patients (N = 123). When the Hypochondriasis and Hysteria scales were used, both versions had a 79% hit rate for inappropriate disability and at least an 80% overall correct classification rate. The resulting brief screening measure included 52 items.
Psychological adjustment generally is believed to contribute to the etiology and prognosis of low back disorders. This has been demonstrated most frequently by the association between the MMPI and the diagnosis and rehabilitation of patients with lowback-related disabilities. In the hope of improving diagnostic accuracy, several investigators have advocated routine use of the MMPI with low back patients (Holmes & Rothman, 1979; Spengler & Freeman, 1979).
Criticisms of the MMPI in this context include practical problems such as its length and seeming irrelevance to the low back patient. Special single MMPI scales that could be used as screening tests do not appear to be valid (Rosen, Frymoyer, & Clements, 1980;Tsushima & Towne, 1979). Two brief diagnostic screening instruments recently have been offered as alternatives. One is a 13-item pain description scale (Leavitt & Garron, 1979). The authors assert that "functional" pain disorders can be distinguished from "organic" pain disorders on the basis of pain complaints. Functional pain supposedly is more intense and more diffuse than organic pain. In their study, Leavitt and Garron (1979) compared patients without organic back disease with patients who had ''as yet undiagnosed abnormalities of the spine [p. 3021." &cause they provided no external validity for these groupings, there is no support for using this measure of selfreported pain as a screening test for functional pain disorders. The other brief diagnostic method is a 10-minute, IS-item structured interview (Hendler, Viernstein, Gucer, & Long, 1979). In the validation study of this device, there were several methodological flaws. Test scores were determined retrospectively from patient records, and the physicians who rated the physical findings were not blind to the results of the psychological measure. Moreover, the correct classification rate of patients as being with or without definite physical findings was worse than expected on the basis of chance.
Abbreviated versions of the MMPI have been constructed to deal with the practical disadvantage of the length of the full MMPI. The Faschingbauer Abbreviated MMPI (FAM) (Faschingbauer, 1974), for example, is correlated significantly with full MMPI scale scores in back patients (Freeman, Calsyn, & O'Leary, 1977;Turner & McCreary, 1978). In addition, there were group differences on the FAM between pain patients with and without definite physical findings (Turner & McCreary, 1978). However, the concordance rates for code types between the FAM and full MMPI are low, and there is no evidence for interpretive validity on an individual case basis. As a result, some authors conclude that there is no justification yet for the use of the FAM with pain patients (Bradley, Prokop, Gentry, Van der Heide, & Prieto, 1981). The present study reports the accuracy of the FAM, in comparison with the full MMPI, for classifying low back patients on an individual basis as appropriately or inappropriately disabled.