Reliability and Validity of the Farsi Version of the Somatosensory Amplification Scale

The somatosensory amplification scale (SSAS) is a 10-item self-report instrument designed to assess a tendency to experience normal somatic and visceral sensations as intense, noxious, and disturbing.

The present study investigated the reliability and validity of the SSAS, developed by Barsky et al. (1988), in the Iranian population.

The study was carried out on 240 patients with functional gastrointestinal disorders and 30 healthy persons selected by convenience sampling from 2013 to 2014. The patients completed the SSAS, the somatization subscale of the symptom checklist-90-revised (SCL-90-R som), and the modified somatic perception questionnaire (MSPQ), whereas the healthy persons completed just the SSAS.

Exploratory factor analysis indicated that the one-factor solution, accounting for 29.42% of the variance, explained that the SSAS items were represented by one global dimension. The SSAS had acceptable internal consistency (α = 0.78) and good test-retest reliability (r = 0.80). The item-to-scale correlations varied from 0.17 to 0.55. Item 2 had the lowest item-total score correlation (r = 0.17), and the α coefficient for the SSAS exceeded when this item was deleted. The convergent validity of the SSAS with somatization was shown with a significant correlation between the SSAS, SCL-90-R som (r = 0.36), and MSPQ scores (r = 0.52). Discriminant validity analysis showed no significant difference in the SSAS between the patient and control groups (P > 0.05) and non-specificity of the SSAS for patients.

In sum, the SSAS has acceptable reliability and validity for the Iranian population and the scale measures the same the original scale, namely somatosensory amplification.