Duration of chronic pain and the Minnesota Multiphasic Personality Inventory: profiles of industrially injured workers.

The present study explored the usefulness of the Minnesota Multiphasic Personality Inventory (MMPI) in understanding the relationship between duration of chronic pain and psychiatric difficulties. The MMPI responses of workers' compensation patients with varying levels of low back pain chronicity were compared. One hundred ninety eight patients, divided into three groups according to length of disability, underwent social history interviews and completed the MMPI. In regard to the overall profile, the sample had elevations on the Hypochondriasis, Depression, and Hysteria scales. A series of analysis of variance designs revealed that those who were disabled for two or more years evidenced significantly more depression and psychopathology than those who were disabled for less than one year. Further statistical evaluation of 200 social history variables did not reveal significant differences between the three groups on most variables. In conjunction with previous research, the results suggested a causative link between disability and psychiatric disease.