Screening for serious mental illness in populations with co-occurring substance use disorders: Performance of the K6 scale.

Serious mental illnesses (SMIs) such as schizophrenia, bipolar disorder, and major depression are prevalent among individuals with substance use disorders, particularly those in drug treatment programs. No screening tool has yet become the gold standard for identifying SMI among individuals with substance use disorders. One candidate instrument, the K6 screening scale, is brief, easy to administer and score, and has performed well, detecting SMI in studies using general population samples. We used data from the National Survey on Drug Use and Health to examine the K6's psychometric properties in a subsample of persons with substance use disorders and found that the K6 accurately screened for severe psychological distress associated with SMI among individuals with substance use disorders and across different psychiatric disorders.