Table 1.

Comparison of published criteria for treatment resistance in schizophrenia with proposed criteria for clozapine eligibility

Published criteria	Itil et al2	Brenner et al8	Kane et al4	Conley and Kelly10	Suzuki et al9	Proposed criteria for clozapine eligibility
Number of AP trials	Not mentioned	3 (different chemical classes)	3 (2 different chemical classes)	2	2	2
Adequate dose, CPZeq	600 mg or Trifluoperazine 80 mg	≥1000 mg	≥1000 mg	400 to 600 mg	≥600 mg	Upper half of the recommended dosing rangea
Adequate duration, weeks	24	6	6	4 to 6	6	6, at adequate dose
No significant improvement	Not mentioned	Not mentioned	<20% decrease on BPRS, and either CGI-S ≥ 4 or BPRS ≥ 45	No clinical improvement	CGI-I ≥ 3, or <20 point increase in GAF and FACT-Sz, or <20% decrease of BPRS and PANSS	CGI-SCH positive change >2 (2 = much improved)b
Current illness severity	Active psychotic symptoms	Persistent positive and negative symptoms; disability in social, self-care, and occupational domains	BPRS ≥ 45, and CGI-S ≥ 4, and ≥4 on at least 2 out of 4 positive items	BPRS > 45, and CGI-S > 4, and >4 on at least 2 out of 4 positive items	CGI-S ≥ 4, and FACT-Sz ≤ 49 or GAF ≤ 50	CGI-SCH positive ≥ 4 (4 = moderately ill)c
Duration of illness with poor functioning, years	2	2	5	5	Not mentioned

AP = antipsychotic; BPRS = Brief Psychiatric Rating Scale; CGI-S = Clinical Global Impression–Severity; CGI-SCH = Clinical Global Impression–Schizophrenia; CPZeq = chlorpromazine equivalents; GAF = Global Assessment of Functioning; FACT-Sz = Functional Assessment for Comprehensive Treatment of Schizophrenia; PANSS = Positive and Negative Syndrome Scale

^aChosen as option based on lack of empiric evidence for establishing dose equivalents⁶¹–⁶³

^bA CGI-SCH positive change score of 2 = Notably better with significant reduction of symptoms, but some symptoms remain; increase in the level of functioning.³⁰

^cA CGI-SCH positive symptom score of 4 = Some prominent symptoms with some interference in the level of daily functioning.³⁰