A fourth empirically derived cluster of chronic pain patients based on the multidimensional pain inventory: Evidence for repression within the dysfunctional group

The authors proposed that chronic pain patients with repressive defenses are not represented in current 3-cluster solutions of the Multidimensional Pain Inventory (MPI; R. D. Kerns, D. C. Turk, & T. E. Rudy, 1985) and that such a group can be distinguished by using a measure of defensiveness together with subscales of the MPI. They expected these patients to be described both by high defensiveness and by elevated pain and disability but minimal emotional distress. For 178 pain patients, hierarchical cluster analyses were performed on the MPI and Balanced Inventory of Desirable Responding (D. L. Paulhus, 1984). A 3-cluster solution replicated past findings in identifying dysfunctional, interpersonally distressed, and adaptive coper groups. A 4-cluster solution fit the data better, with a repressor group described by high pain, low activity and low distress emerging from the dysfunctional group. Profile analysis of validation measures showed that repressors scored comparably with dysfunctional patients on somatic symptoms of depression, pain severity, and perceived disability but significantly higher on these factors than the adaptive copers. Repressors scored comparably with adaptive copers on cognitive-affective symptoms of depression, anxiety, and anger but significantly lower on these variables than dysfunctional patients. Repressors also reported greater pain severity and perceived disability relative to their reports of negative affect, whereas dysfunctional and adaptive coper groups exhibited no such disparities. Without a measure of defensiveness, the MPI may misclassify a distinct group of patients as dysfunctional, but who readily endorse physical symptoms yet report low levels of emotional distress.