Detecting differences in diagnostic assessment of bipolar disorder

Area of Science:

• Psychiatry
• Clinical Psychology
• Diagnostic Assessment

Background:

• Semistructured diagnostic interviews are standard for psychiatric assessment but involve subjective interpretation of criteria.
• Variability in applying diagnostic thresholds can lead to inconsistent bipolar disorder diagnoses in research.
• The Rhode Island Methods to Improve Diagnostic Assessment and Services project aims to address these diagnostic inconsistencies.

Purpose of the Study:

• To illustrate how a self-report scale, the Mood Disorder Questionnaire (MDQ), can detect systematic differences in applying bipolar disorder diagnostic criteria.
• To demonstrate the wide variation in how different groups diagnose bipolar disorder, even when controlling for sample prevalence.

Main Methods:

• Compared bipolar disorder diagnosis frequencies from four studies using the Structured Clinical Interview for DSM-IV (SCID) and the MDQ.
• Analyzed the prevalence rates of MDQ-positive cases and the ratio of SCID diagnoses to MDQ cases across studies.
• Examined the rank order of prevalence for both MDQ and SCID diagnoses to identify discrepancies.

Main Results:

• Bipolar disorder prevalence rates from SCID diagnoses varied significantly (10.9% to 76.2%), a 7-fold difference.
• MDQ-positive case prevalence showed less variability (17.8% to 31.2%), a less than 2-fold difference.
• The SCID/MDQ ratio differed significantly between studies, indicating inconsistent diagnostic practices.

Conclusions:

• A self-administered scale like the MDQ can effectively detect systematic differences in diagnostic practices for bipolar disorder.
• Significant variation exists in the bias toward diagnosing bipolar disorder, even after accounting for sample prevalence differences.
• The MDQ offers a more consistent measure for identifying bipolar disorder prevalence compared to traditional clinical interviews.