Diagnostic Interview for Genetic Studies: Validity and Reliability of the Croatian Version.

Objective To test the validity and reliability of the Diagnostic Interview for Genetic Studies (DIGS) in patients with mental illness in Croatia. Materials and methods Following translation, back-translation, and pilot testing, the Croatian version of DIGS (CRO-DIGS) was administered to a total of 150 inpatients and outpatients diagnosed at the Clinical Hospital in Split with bipolar and major depressive disorder (n=56), schizophrenia and schizoaffective disorder (n=62), and alcohol dependence or use disorders (n=32). Initial testing was performed independently by one interviewer and one observer blinded to the diagnosis, and a retest was performed after 8 weeks by a third examiner. Results The validity of CRO-DIGS was high (&kgr;=0.916), with an excellent inter-rater (&kgr;=0.824) reliability, especially for bipolar disorder (&kgr;=0.956). Following an 8 week test–retest interval, the reliability for all diagnoses was found to be excellent (&kgr;=0.843). Conclusion Our study has shown excellent validity and reliability of the Croatian version of DIGS, making it a promising instrument to assess mental illness of patients. The development of a valid and reliable diagnostic tool such as the CRO-DIGS will considerably advance the scientific communities’ ability to carry out genetic studies of psychiatric illness in the region.