Comparing the dis with the scid: Chronic fatigue syndrome and psychiatric comorbidity

This study investigated whether psychiatric comorbidity rates in individuals with Chronic Fatigue Syndrome (CFS) change as a function of the type and scoring of psychiatric interview instruments used. The number of DSM-III-R, Axis I psychiatric diagnoses were assessed two times for each of the 18 participants with CFS, once using the Diagnostic Interview Schedule (DIS) and once using the Structured Clinical Interview for the DSM-III-R (SCID). Participants received a significantly greater number of current and total lifetime psychiatric diagnoses resulting from the DIS interview, as opposed to the SCID interview. Fifty percent of participants received at least one current psychiatric diagnosis on the DIS, whereas only 22% received a current psychiatric diagnosis on the SCID. Findings suggested that psychiatric comorbidity rates in individuals with CFS are influenced by the type of psychiatric instrument used. These results help explain the large discrepancies in findings for psychiatric illness in individuals with CFS across investigative studies.