Can clinical features of bipolar-I disorder be assessed reliably on the telephone?

The reliability of telephone interviews for rating 25 selected individual items of the Diagnostic Interview for Genetic Studies (DIGS) was assessed among persons with remitted bipolar disorder I (BPD I, n = 20).

The Diagnostic Interview for Genetic Studies (DIGS) was administered directly (with two raters present) and by telephone in random order to 20 adults with bipolar disorder I.

Telephone interviews achieved reliability comparable to direct interviews for 16 items (64%), but were considered unsatisfactory for seven others (28%). Two other items, which evaluated the overlap between substance abuse and mood disorder, were considered unreliable for both methods of interview.

The presence of two interviewers for the in-person interview may have led to over-estimation of in-person reliability. Investigator bias in favor of phone interviews and a relatively small sample may have confounded the results.

Telephone interviews may be used to evaluate individuals with BPD I in remission, provided the limitations of this method are recognized. They have limited reliability for dissecting overlap between mood abnormalities and psychotic phenomena or substance abuse.