Study design: Prospective study on predicting psychopathology in chronic occupational spinal disorders (COSDs).
Objective: To assess prevalence of specific profiles on the Minnesota Multiphasic Personality Inventory (MMPI) and their ability to predict psychopathology in a COSD cohort.
Summary of background data: In the relatively small number of COSDs that develop chronic pain and disability, the MMPI-2 has been an important part of the psychosocial assessment. Certain profiles have been thought to have a high prevalence in COSD. They have also been widely popularized as predicting certain treatment outcomes, and have often been used to "screen" surgical and rehabilitation candidates.
Method: Of an initial cohort of 1,489 consecutive COSD patients completing a valid prerehabilitation MMPI-2, 1,185 patients (79.6%) were classifiable into one of four MMPI profile groups. A new Disability Profile (DP) group was identified, which was the most common profile. Patients attended a 5- to 7-week interdisciplinary rehabilitation program. They completed a psychosocial assessment battery, and a Structured Clinical Interview for DSM IV diagnosis (SCID-I and II) was administered as the "gold standard" for defining psychopathology. One year postrehabilitation, a structured clinical interview assessed socioeconomic outcomes.
Results: A previously unrecognized MMPI profile, now termed the DP, was found to have a prevalence of 53.2% of the whole group, and 66.9% of those with "classifiable" MMPI profiles in this large population of COSD patients. Only 6.9% of subjects had normal profiles (NP), while only 19.5% had profiles previously thought to occur commonly in this population. NP patients were twice as likely to retain work 1 year after treatment than the 3 abnormal MMPI groups combined. The DP group was 14 times more;1 likely to have an Axis I diagnosis (such as depression or anxiety) than the NP group, and was also almost 5 times more likely have an Axis II personality disorder diagnosis.
Conclusions: The prevalence of commonly cited MMPI profiles, often used for presurgical or chronic pain screening in this population, is relatively small. The prevalence of four or more elevations (DP), however, is large, representing two thirds of patients demonstrating any classifiable MMPI pattern. The DP group showed extremely high levels of associated psychopathology, which raises "red flags" to the surgeon likely to operate on such patients, or the interdisciplinary pain team. Screening COSD patients with the MMPI-2 may be effective in identifying psychopathology, but only if the physician is aware that the DP is commonplace and significant.