Somatoform dissociation among Swedish adolescents and young adults: The psychometric
properties of the Swedish versions of the SDQ-20 and SDQ-5
Sammanfattning
Background: Somatoform dissociation is supposed to be a vital aspect of the general concept of
dissociation. The Somatoform Dissociation Questionnaire-20 (SDQ-20) and the brief version SDQ-5
are self-report instruments constructed to identify somatic dissociation. Aim: In the present study, the
psychometric qualities of the Swedish version of the SDQ-20 and its brief version, the SDQ-5, were
examined among adolescents and young adults. Reliability and concurrent validity were
investigated. Methods: A total of 512 adolescents and young adults participated in the study: 461
adolescents from a non-clinical sample and 50 adolescents and young adults from a clinical eating
disorder outpatient unit. They completed the self-report instruments the SDQ-20, the SDQ-5 (part of
SDQ-20), the Linköping Youth Life Experience Scale (LYLES, a trauma history scale) and the
Dissociation Questionnaire-Sweden (Dis-Q-Sweden). Results: Both internal consistency and test-
retest reliability of the Swedish version of SDQ-20 were good in both the non-clinical (a = 0.83) and
the clinical groups (a = 0.84); the reliability for the SDQ-5 was, however, lower (non-clinical a = 0.50,
clinical a = 0.64). Significant differences were found between the clinical and non-clinical groups on
both somatoform and psychoform dissociation. Correlations between the Dis-Q-Sweden, SDQ-20 and
SDQ-5 were generally high. The criterion and convergent validity was acceptable for both scales but
somewhat better for SDQ-20 than for SDQ-5. Conclusion: The advantage with both the SDQ-20 and the
SDQ-5 is that they are short questionnaires, but the results suggests that SDQ-20 is preferable based
on the higher-quality psychometric properties of the SDQ-20.