In analyses of the early, pivotal studies of clozapine,
compared with chlorpromazine, carried out in mixed- and
in refractory-patient samples, we observed 2 trajectory
groups. Over 70% of the mixed patient sample was assigned
to the early-good trajectory group, and the absolute amount
of improvement in symptom severity was over 60%. For
the refractory patients, about 27% more clozapine-treated,
compared with chlorpromazine-treated, patients were
observed to have an early-good trajectory. These clozapinetreated
patients had mean improvement of symptom
severity of more than 45%. Considering clozapine-treated
patients in the delayed-partial response trajectory groups to
be nonresponders, the rates were 20% in the mixed study,
and 29% in the refractory study.