Validation and Factor Structure Analysis of the Polish Version of the Somatosensory Amplification Scale (SSAS-PL) in Clinical and Non-Clinical Samples.

The aim of this study was to validate the Polish version of the Somatosensory Amplification Scale (SSAS-PL) and examine its psychometric properties in clinical and non-clinical samples. : The study included 1128 participants (711 healthy adults, 194 cardiac patients, 223 psychiatric patients). The analyses were categorized into exploratory and confirmatory phases. Exploratory analyses were conducted on a randomly selected sample that comprised 60% of the study participants (training sample) to estimate the reliability (Cronbach's alpha) and factorial validity (EFA with varimax rotation). Confirmatory analyses were performed on an independent (test) sample that represented 40% of the total sample size to facilitate the cross-validation of the factor structure (CFA) and to assess the convergent and discriminant validities (using the HTMT method) in relation to health anxiety (SHAI) and psychopathological symptoms (KOFF-58). Additionally, measurement invariance was examined with respect to gender (female vs. male) and health status (healthy vs. clinical). The SSAS-PL demonstrated good internal consistency (α = 0.75-0.78) after removing item 1. A one-factor structure showed the best fit and theoretical interpretability. The measurement invariance was supported across clinical groups. The SSAS-PL showed convergent validity with the measures of somatic symptoms, anxiety, and health anxiety. It demonstrated discriminant validity from other psychopathology measures. The SSAS-PL was a reliable and valid measure of somatosensory amplification in the Polish population. Its unidimensional structure aligned with most cross-cultural adaptations. The scale may be useful for assessing somatosensory amplification in both research and clinical settings in Poland. Further research on its utility in specific clinical populations is warranted.