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.