(178) MMPI-2 validity scale code-types in chronic headache and orofacial pain

Abstract

The MMPI-2 has been widely used to classify chronic pain patients into clinically meaningful code-types based on cluster analysis of its clinical scales. These code-types have often been used to assess a patient’s psychological status, to design treatment interventions and to predict treatment outcome. A major strength of the MMPI-2 is its validity scales designed to measure test-taking approaches that may impact MMPI-2 test validity. The primary validity scales are: L (Lie Scale), F (False Item Scale) and K (Defensiveness Scale). In contrast to the MMPI-2’s clinical scales, there is a relative lack of pain research investigating whether clinically meaningful validity scale code-types might emerge. To examine this question, the MMPI-2 validity scales L, F and K were obtained from 400 chronic headache and orofacial pain patients and a K-means cluster analysis was performed. Analysis revealed three “good” validity scale clusters and a fourth cluster that did not achieve significance: Cluster 1 Hyperdefensive Code-type, included 127 participants (31%) and final cluster centers showed elevated L (63.1) and K (61.4) scores and slightly low F (48.8) scores. Cluster 2, Normal Code-type, included 165 participants (40%) and final centers showed somewhat low L (46.8) scores, and normal F (49.4) and K (51.0) scores. Cluster 3, Distressed, included 92 participants (about 22% of the sample) and final cluster centers reflected normal L (50.2) scores, elevated F (69.50) scores and low K (44.6) scores. Cluster 4, Severe Distress or Malingering, included only 22 participants, 5% of the of the total sample. Final cluster centers showed somewhat low L (47.9) scores, very high F (100.0) scores and very low K (36.3) scores. These validity scale code-types point to distinct differences in how chronic pain patents may approach taking the MMPI-2, thus impacting test validity and accuracy of interpretation. The MMPI-2 has been widely used to classify chronic pain patients into clinically meaningful code-types based on cluster analysis of its clinical scales. These code-types have often been used to assess a patient’s psychological status, to design treatment interventions and to predict treatment outcome. A major strength of the MMPI-2 is its validity scales designed to measure test-taking approaches that may impact MMPI-2 test validity. The primary validity scales are: L (Lie Scale), F (False Item Scale) and K (Defensiveness Scale). In contrast to the MMPI-2’s clinical scales, there is a relative lack of pain research investigating whether clinically meaningful validity scale code-types might emerge. To examine this question, the MMPI-2 validity scales L, F and K were obtained from 400 chronic headache and orofacial pain patients and a K-means cluster analysis was performed. Analysis revealed three “good” validity scale clusters and a fourth cluster that did not achieve significance: Cluster 1 Hyperdefensive Code-type, included 127 participants (31%) and final cluster centers showed elevated L (63.1) and K (61.4) scores and slightly low F (48.8) scores. Cluster 2, Normal Code-type, included 165 participants (40%) and final centers showed somewhat low L (46.8) scores, and normal F (49.4) and K (51.0) scores. Cluster 3, Distressed, included 92 participants (about 22% of the sample) and final cluster centers reflected normal L (50.2) scores, elevated F (69.50) scores and low K (44.6) scores. Cluster 4, Severe Distress or Malingering, included only 22 participants, 5% of the of the total sample. Final cluster centers showed somewhat low L (47.9) scores, very high F (100.0) scores and very low K (36.3) scores. These validity scale code-types point to distinct differences in how chronic pain patents may approach taking the MMPI-2, thus impacting test validity and accuracy of interpretation.