Specificity of MMPI cluster types to chronic illness

Cluster analysis derived MMPI profile types were compared for three distinct illness populations: chronic low back pain (CLBP), mixed headache (HA), and cardiac disease (CD). Results replicated previous findings in the chronic pain and cardiac literatures. Differences between diagnostic groups and genders were found for the prevalence of the derived MMPI profile types. Results indicated that, in males, the two chronic pain groups had similar profile types and similar relative frequencies of these types, but both differed from the CD sample. The chronic pain groups tended to have a greater number of patients with pathological and distressed MMPI profile types and a lesser representation in the subclinical profile type compared to the CD sample. Similar findings were obtained for females, though the CLBP group tended to have a higher frequency of highly distressed, pathological profiles than either the HA or CD groups. Results suggested that the MMPI may be a measure of response to illness rather than reflecting predisposing personality types for any given illness and that the higher frequency of highly distressed profiles in the chronic pain samples reflects the increased suffering of those populations compared to other illnesses.