Validity of the assessment of bipolar spectrum disorders in the WHO CIDI 3.0

Although growing interest exists in the bipolar spectrum, fully structured diagnostic interviews might not accurately assess bipolar spectrum disorders. A validity study was carried out for diagnoses of threshold and sub-threshold bipolar disorders (BPD) based on the WHO Composite International Diagnostic Interview (CIDI) in the National Comorbidity Survey Replication (NCS-R). CIDI BPD screening scales were also evaluated.

The NCS-R is a nationally representative US household population survey (n=9282 using CIDI to assess DSM-IV disorders. CIDI diagnoses were evaluated in blinded clinical reappraisal interviews using the non-patient version of the Structured Clinical Interview for DSM-IV (SCID).

Excellent CIDI-SCID concordance was found for lifetime BP-I (AUC=.99 kappa=.88, PPV=.79, NPV=1.0), either BP-II or sub-threshold BPD (AUC=.96, kappa=.88, PPV=.85, NPV=.99), and overall bipolar spectrum disorders (i.e., BP-I/II or sub-threshold BPD; AUC=.99, kappa=.94, PPV=.88, NPV=1.0). Concordance was lower for BP-II (AUC=.83, kappa=.50, PPV=.41, NPV=.99) and sub-threshold BPD (AUC=.73, kappa=.51, PPV=.58, NPV=.99). The CIDI was unbiased compared to the SCID, yielding a lifetime bipolar spectrum disorders prevalence estimate of 4.4%. Brief CIDI-based screening scales detected 67-96% of true cases with positive predictive value of 31-52%.

CIDI prevalence estimates are still probably conservative, though, but might be improved with future CIDI revisions based on new methodological studies with a clinical assessment more sensitive than the SCID to sub-threshold BPD.

Bipolar spectrum disorders are much more prevalent than previously realized. The CIDI is capable of generating conservative diagnoses of both threshold and sub-threshold BPD. Short CIDI-based scales are useful screens for BPD.