Diagnostic field reliability in forensic mental health evaluations

How likely are multiple forensic evaluators to agree on defendants' diagnoses in routine forensic mental health evaluations? A total of 720 evaluation reports were examined from 240 cases in which 3 evaluators, working independently, provided diagnoses for the same defendant. Results revealed perfect agreement across 6 independent diagnostic categories in 18.3% of cases. Agreement for individual diagnostic categories was higher, with all 3 evaluators agreeing on the separate presence of psychotic, mood, or substance disorders in more than 64.7% of cases and agreeing on the presence of cognitive or developmental disorders in more than 89.7% of cases. However, evaluators agreed about the combination of psychotic and substance-related diagnoses in only 46.5% of cases. Agreement was enhanced by diagnoses with low base rates, and it was suppressed in evaluations conducted in jails. Psychiatrists and contracted evaluators were more likely to provide dissenting diagnostic categories than psychologists and state-employed evaluators. These results are among the first to document diagnostic agreement among nonpartisan practitioners in forensic evaluations conducted in the field, and they allow for practice and policy recommendations for evaluators in routine forensic practice to be made. (PsycINFO Database Record