Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Symptom severity
Systematic review	142 people 2 RCTs in this analysis	Mean difference in Positive and Negative Syndrome Scale (PANSS) positive subscore with clozapine with quetiapine Absolute results not reported	–0.70 95% CI –2.07 to +0.68		Not significant
Systematic review	72 people Data from 1 RCT	No clinically important change in negative symptoms short term with clozapine (initial dose 50 mg/day, after 10 days 400–600 mg) with quetiapine (initial dose 100 mg/day, after 10 days 400–700 mg) Absolute results not reported	RR 0.94 95% CI 0.78 to 1.13		Not significant
Systematic review	142 people 2 RCTs in this analysis	Mean difference in PANSS negative subscore end of study with clozapine (mean dose 292.4 mg/day) with quetiapine (mean dose 369 mg/day) Absolute results not reported	Mean difference –2.23 95% CI –3.48 to –0.99	Effect size not calculated	quetiapine
Systematic review	67 people Data from 1 RCT	Mean difference in SANS negative symptom score short term with clozapine (100–550 mg/day, mean 256 mg/day) with quetiapine (150–650 mg/day, mean 362 mg/day) Absolute results not reported	Mean difference –1.64 95% CI –8.17 to +4.89		Not significant