Diagnostic reliability of bipolar II disorder

Area of Science:

• Psychiatry
• Genetics
• Clinical Psychology

Background:

• Diagnostic reliability for hypomania and bipolar II (BPII) disorder is less established than for major depression and mania.
• Accurate diagnosis is crucial for genetic studies, as bipolar I (BPI) and BPII disorders often co-occur within families.
• This study aimed to assess diagnostic reliability for BPI, BPII, recurrent unipolar disorder, and their constituent episodes.

Purpose of the Study:

• To evaluate the diagnostic reliability of bipolar II disorder and related mood episodes.
• To ensure accurate diagnoses for a genetic study of bipolar I disorder.
• To establish confidence in diagnostic procedures for complex mood disorders.

Main Methods:

• Assessed reliability using co-rated and test-retest interviews (Schedule for Affective Disorders and Schizophrenia-Lifetime version).
• Utilized best-estimate diagnoses from two independent psychiatrists for 524 subjects in a genetic linkage study.
• Applied Research Diagnostic Criteria, with specific criteria for BPII disorder.

Main Results:

• Complete agreement was observed for diagnosing major depressive, manic, and hypomanic episodes in co-rated interviews.
• High Cohen kappa coefficients indicated strong reliability for test-retest interviews (manic: 0.83, hypomanic: 0.72, major depressive: 1.0).
• Excellent reliability was achieved at the best-estimate level for BPI (0.99), BPII (0.99), and recurrent unipolar disorder (0.98).

Conclusions:

• Good interrater reliability for bipolar II disorder is achievable.
• Experienced psychiatrists performing interviews and best-estimate diagnoses ensure high reliability.
• Findings support the use of these diagnostic procedures in genetic studies of bipolar disorder.