Two hundred eighty-seven outpatients with TRS receiving
clozapine for more than 1 year were divided into 2 groups based on the need for a second
antipsychotic medication and/or electroconvulsive therapy after receiving
clozapine in the maximum tolerable dose for at least 3 months.
RESULTS/FINDINGS: One hundred two patients (35.4%) were considered to be
clozapine nonresponders. Compared with responders,
clozapine nonresponders were more often unemployed at the time of starting
clozapine (P = 0.04), had a longer duration of untreated
psychosis (P = 0.007), had received significantly higher number of adequate
antipsychotic trials in the past (P = 0.02), had received
antipsychotic polypharmacy in the past (P = 0.01), had experienced adverse effects with first- (P < 0.001) and second-generation
antipsychotics (P = 0.01), and had more medical comorbidities (P = 0.03). The nonresponders more frequently had
visual hallucinations (P = 0.001), and feelings/acts or impulses attributed to some external source (P = 0.03) in the lifetime, and had a significantly higher Clinical Global Impression severity score at the time of starting of
clozapine (P < 0.001). While on
clozapine, nonresponders received significantly higher dose of
clozapine (P = 0.001) and higher proportion of them experienced
constipation (P = 0.04),
hypersalivation (P = 0.002), and obsessive-compulsive symptoms (P = 0.05) as adverse effects of
clozapine.
CONCLUSIONS/IMPLICATIONS: The present study shows that approximately one-third of patients with TRS do not respond to
clozapine. However,
clozapine nonresponders, although broadly similar in sociodemographic profile to
clozapine responders, differ from
clozapine responders on past treatment profile.