Invariance of SCL-90-R dimensions of symptom distress in patients with peri partum pelvic pain (PPPP) syndrome

Objectives. There are no studies available that have examined the factorial invariance of dimensions underlying the Symptom Checklist-90-Revised (SCL-90-R) across at least three distinct samples. In the following study, we wished to determine whether a dimensional model comprising eight primary factors previously identified in psychiatric out-patients, phobics and the general population (Arrindell & Ettema, 2003) could be extended to a homogeneous sample of pain patients comprising females suffering from peri partum pelvic pain (PPPP) syndrome (N = 413). The internal consistency and discriminant validity of the dimensions were also examined. Method. The SCL-90-R and measures of disability, pain-related fear, pain intensity and fatigue were administered to the participants. The multiple group method was used to determine factorial invariance. Pearson correlations were determined between the SCL-90-R and aforementioned measures. Results. The factorial invariance of an 8-dimensional model of primary factors underlying the SCL-90-R, namely, agoraphobia, anxiety, depression, somatization, cognitive-performance deficits, interpersonal sensitivity-mistrust, acting-out hostility and sleep difficulties, was extended with success to the present sample of PPPP patients. In spite of substantial correlations between the internally consistent SCL-90-R symptom dimensions, some evidence of discriminant validity was reported in that specific subscales showed different patterns of correlations with measures of disability, pain-related fear, pain intensity and fatigue. Conclusions. The 8-dimensional system based on the work of Arrindell and Ettema (2003) was invariant across psychiatric patients, phobics, the general population and pain patients. The invariance of the SCL-90-R hostility dimensions may have implications for a re-formulation of Watson and Clark's tripartite model of general distress, specific anxiety and specific depression.