Assessment of formal thought disorder: The relation between the Kiddie Formal Thought Disorder Rating Scale and clinical judgment

The presence of formal thought disorder (FTD) in childhood is sometimes viewed as a possible precursor of psychotic symptoms or adult schizophrenia. It is possible to assess FTD in childhood in a valid and reliable manner, by using the Kiddie Formal Thought Disorder Rating Scale (K-FTDS). However, training and rating procedures are very time consuming, and may be particularly difficult during clinical assessment. The aim of this study was therefore to compare the clinician's rapid judgment of FTD to the detailed ratings of the K-FTDS. The K-FTDS was administered to 172 consecutively referred children, aged 6 to 12 years and subsequently rated by two blind raters. The same criteria, as used in the K-FTDS (illogical thinking, loose associations, incoherence, and poverty of content of speech), were rated by nine clinicians. The overall agreement between K-FTDS scores and FTD scores as rated by the clinician was low. The clinician's judgment of FTD did not correspond very highly with ratings on the K-FTDS. Thus, although detecting FTD has important clinical value, the assessment of its presence or absence seemed to depend highly on which measure was used.