The February 2001 issue of ARCHIVES carries a report on the use of the
Bonn Scale for the Assessment of Basic Symptoms (BSABS), a screening measure
for the early detection of schizophrenia.1
In this sample of nonpsychotic outpatients, of those who reported at least
one prodromal symptom on the BSABS, 70% subsequently developed the illness.
The instrument seems to have a better positive predictive value than other
measures of prodromal states2 and a relatively
low false-positive rate (specificity = 0.59). Because the false-negative rate
of the instrument is low (sensitivity = 0.98), the researchers conclude that
the measure "seems applicable to a broad identification of at-risk persons
in the general population."2(p163)