Is the MMPI invalid for assessing psychological disturbance in pain related organic conditions?

The Minnesota Multiphasic Personality Inventory (MMPI) was analyzed in 30 patients with fibromyalgia and 30 patients with rheumatoid arthritis (RA). Eighteen statements on the hypochondriasis, depression and hysteria scales and 14 statements on the schizophrenia scale differentiated patients with fibromyalgia and RA. Patients with fibromyalgia had higher scores on 29 of the 32 statements. Patients with RA seemed appropriately concerned about health and the possibility of additional illness. By contrast, patients with fibromyalgia were more symptomatic and presented a more unusual and complex syndrome, raising the possibility of a somatoform disorder and also greater personal distress in these patients. On the basis of analyzing the scores of patients with RA, one can also conclude that physical illness alone is not sufficient to drive MMPI profiles into the abnormal range. Patients with fibromyalgia who have a similar degree of pain intensity compared with patients with RA (61.3 vs 60 on a scale of 100) have significantly more abnormal MMPI, and analysis of their MMPI suggest a more complex somatic syndrome and greater psychological disturbance.