Cluster analysis of Minnesota Multiphasic Personality Inventory (MMPI) profiles in a chronic headache population.

Minnesota Multiphasic Personality Inventory (MMPI) profiles from 123 chronic headache sufferers (48 migraine, 47 muscle contraction, 28 mixed) were cluster analyzed in order to replicate results from other pain populations and to examine differences among the clusters along headache parameters and demographic variables. Four homogeneous subgroups were obtained and a multiple discriminant analysis was successful in correctly classifying 97.56% of the headache subjects. Obtained clusters closely resembled those evidenced in previous pain research. Results indicated that diagnostic category was unrelated to cluster membership; however, frequency of headache occurrence was a differentiating factor. Implications for headache treatment and future research are discussed.