[Validity and reliability of the Turkish form of symptom interpretation questionnaire]

This study was undertaken to investigate the validity and reliability of the Turkish version of Symptom Interpretation Questionnaire (SIQ) that was developed by Robbins and Kirmayer (1991).

Subjects of the study were: 53 patients with medically unexplained somatic complaints (MUS) that were referred to I. Psychiatry Clinic of Ankara Numune Teaching and Research Hospital, 26 patients who were diagnosed as Major Depressive Disorder (MDD) based on their mental complaints, and 71 healthy individuals (Control).

Construct validity of SIQ was studied with factor analysis and the scale is statistically shown to consist of three theoretical styles of symptom attribution; normalizing, psychologizing and somatizing. Criterion related validity of normalizing subscale was shown with the absence of significant correlations between SIQ-normalizing scale and either Toronto Alexythimia Scale-20 or SIQ-number of symptoms. Validity of psychologizing subscale was demonstrated by obtaining higher significant mean psychologizing subscale scores in MDD group when compared with mean scores in MUS and Control groups. Criterion related validity of somatizing subscale was shown with significant correlations between SIQ-somatizing scale and SIQ- number of symptoms, and by demonstrating that mean somatizing subscale scores in patients with history of physical disease was significantly higher from mean scores in patients without such history. Internal reliability of SIQ subscales were, alpha=0.86 for normalizing subscale, alpha=0.87 for psychologizing subscale and alpha=0.87 for somatizing subscale.

Internal reliability, criterion related validity, discriminating power for specific groups and construct validity of the SIQ Turkish version were demonstrated to be satisfactorily valid and reliable.