Bipolar disorder questionnaires limited for patients with SUD

By Lucy Piper, Senior medwireNews Reporter

Researchers advise caution when using the Mood Disorder Questionnaire (MDQ) and the Hypomania Checklist-32 (HCL-32) to diagnose bipolar disorder in patients treated for substance use disorders (SUD).

They found that, while both instruments had high negative predictive values and so were effective in ruling out bipolar disorder in these patients, they both had positive predictive values below 50%, suggesting they are limited for ruling in the disorder.

"As always, but particularly in samples with considerable overlap of psychiatric symptoms and risk of misdiagnosis, such as individuals presenting with BD [bipolar disorder] and SUD, a thorough psychiatric evaluation is necessary," say Jean-Michel Aubry (Geneva University Hospital, Switzerland) and colleagues.

The researchers tested the MDQ and HCL-32 in 152 patients, of whom 103 were receiving treatment for alcohol dependence and 49 for opiate dependence.

According to the Structured Clinical Interview for DSM-IV axis I disorders, 33 (21.7%) of the participants had a bipolar spectrum disorder (two had bipolar I disorder, 21 had bipolar II disorder, and 10 bipolar not otherwise specified).

Overall, the HCL-32 showed higher sensitivity for diagnosing bipolar disorder than the MDQ, at 90.9% versus 66.7%. However, the MDQ was more specific than the HCL-32, at 77.3% versus 38.7%.

The MDQ was more sensitive and had a higher specificity for diagnosing bipolar disorder in patients treated for alcohol dependence (71.4 and 82.9%, respectively) compared with opiate dependence (58.3 and 64.9%, respectively). By comparison, the HCL-32 was highly sensitive in both patients with alcohol dependence and opiate dependence (85.7 and 100.0%, respectively), but poorly specific in both groups (39.0 and 37.8%, respectively).

The researchers comment in European Psychiatry that, given their findings, "recommending the use of either the MDQ or the HCL-32 in SUD populations might depend on several factors."

They note that the MDQ demonstrated "adequate" performances with regard to sensitivity and specificity and showed good acceptability in theirs and other studies. "On the other hand, higher sensitivity of the HCL-32 was an advantage," they add.

However, "consequences of low specificity should not be underestimated," they say, "as high false-positive rates might raise issues related with feasibility and cost of subsequent clinical interviews needed to confirm BD diagnosis in patients with positive screening."

The researchers did find that increasing the cut-off value for the HCL-32 from 14 to 19 symptoms increased specificity from 38.7% to 80.7%, while decreasing sensitivity from 90.9% to 72.7%, but even with this change the positive predictive value remained just above 50%.

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