Psychometric properties of the Stress and Crisis Inventory (SCI-93) in females with fibromyalgia and chronic widespread pain

Abstract

Background: Fibromyalgia (FM) and chronic widespread pain (CWP) are commonly associated with symptoms such as fatigue, stiffness, tension, exhaustion and psychological distress. Research on biological markers of the degree of stress symptoms has been conducted for decades. However, biological markers do not offer sufficient information for clinical practice, and thus, validated rating scales are still the best assessment option. The Stress and Crisis Inventory-93 (SCI-93) was designed to assess the severity of symptoms that are primarily related to the autonomous nervous system. Objective: The purpose of this study was to evaluate the psychometric properties of the SCI-93 with regard to known-group validity, internal consistency and test–retest reliability. Methods: The study included 166 women with FM or CWP in addition to 157 age-matched healthy women. The test–retest reliability was investigated in 40 women with FM. Results: A one-factor solution was chosen, which explained 53% of the total variance; Cronbach's alpha was 0.98. The group of patients with FM and CWP showed significantly higher SCI-93 total scores than the healthy reference group (mean = 76.4 ± 24.9 vs. mean = 24.9 ± 21.3; P < 0.001), supporting known-group validity. In the test–retest reliability study, the intra class correlation for the SCI-93 total score was 0.95. Conclusions: The SCI-93 demonstrated satisfactory known-group validity and test–retest reliability. The instrument appears to reflect well the severity of autonomous symptoms.