(P26-013-24) Factor Structure and Psychometric Properties of the Somatic Symptom Disorder – B Criteria Scale (SSD-12) Among Candidates for Bariatric Surgery

Objectives: Patients with clinically significant obesity often present with somatic symptoms such as chronic pain, fatigue, and shortness of breath. The Somatic Symptom Disorder – B Criteria Scale (SSD-12) was developed to assess the cognitive, affective, and behavioral impact of somatic symptoms, but this questionnaire has not been validated in the bariatric patient population. The purpose of this study was to evaluate the psychometric properties and clinical utility of the SSD-12 among candidates for bariatric surgery.

Methods: Patients (n = 480, ages 19-72, 84% female) completed the SSD-12 questionnaire during a presurgical psychosocial-behavioral consultation to assess readiness for bariatric surgery. Descriptive statistics and reliability coefficients were computed to assess the psychometric properties of the questionnaire and item-level characteristics. Confirmatory factor analysis was performed using polychoric correlations and a robust estimator for Likert-type data. Consistent with prior research using the SSD-12, both three-factor (cognitive, affective, behavioral) and single-factor (unidimensional) models were tested for their suitability in the bariatric patient population.

Results: The SSD-12 questionnaire exhibited high internal consistency in the clinical sample (Cronbach’s α = 0.90, McDonald’s ω = 0.94). Compared to the general population, SSD-12 sum scores indicated a very high level of somatic symptom burden among presurgical bariatric patients (x̅ = 16.82, SD = 10.3), with the average score exceeding the 75th percentile for normative, age-matched cutoffs among both women and men. Due to extreme collinearity between the cognitive and affective factors (r = 0.99), the three-factor structure was not tenable. The unidimensional model showed mixed performance, with some criteria suggesting good fit (TLI = 0.94, CFI = 0.95, SRMR = 0.07), and other measures indicating misfit (χ² = 458.82, P < 0.001, RMSEA = 0.13). Items 7 and 10 – considering others’ perceptions of the patient’s own symptom severity – showed particularly poor performance in all analyses, with small polychoric correlations and standardized factor loadings.

Conclusions: The SSD-12 is a suitable questionnaire for assessing somatic symptomatology for bariatric patients, who reported high somatic symptom burden.

Funding Sources: N/A